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1. Display Type Description Message Normal Displays printable characters using the There are four display types Display font of the control Non printable Cigal backsiash characters display as boxes V Codes Displays backslash codes for all There sare sfour sdisplay st Display non printable characters ypes n sis sa sbackslash Password Displays an asterisk for each ERR RR ee RR Ae ek ERR Display character including spaces KEEEEEEAR EER SERRE Hex Display Displays the ASCII value of each 5468 6572 6520 6172 6520 666F character in hex instead of the character itself 7572 2064 6973 706C 6179 2074 7970 6573 2E0A 5C20 6973 2061 2062 6163 6B73 6C61 7368 2E Tables LabVIEW User Manual Use the table control located on the Controls List amp Table palette to create a table on the front panel Each cell in a table is a string and each cell resides in a column and a row Therefore a table is a display for a 2D array of strings Figure 9 1 shows a table and all its parts Refer to the Arrays section of this chapter for more information about arrays ni com Chapter 9 Grouping Data Using Strings Arrays and Clusters Q D x 2 y sqrt x 0 0000 10 0000 0 5963 0 8788 3 1 3163 1 0711 29078 1 3058 0 05698 0 8688 5 0799 1 5013 1 Cell indicated by index values 5 Row headings 2 Column headings 6 Horizontal index 3 Vertical scr
2. eeeseesceeeseeeeeeeenreeseeeeeeeeee LabVIEW Example VIS eeceececeseeseeeeseeeseeeeeeeneeeees Lab VIEW Tools reisiin a T Chapter 2 Introduction to Virtual Instruments Front Pane les eecicscesscevcuvaceeccetsteccncs evs tecsustontieunes tusedeuacvecuitelne iuetoesteess Block Diagrami e a Rdg E AE Terminals iocs cesses ocsascevcchs euss a a I E E ROSIE OTEL n UNA SA AE ads N EA Rees Icon and Connector Pane sosososeseseersesrrrreessrssssssessrrerreerereeeesssses Using and Customizing VIs and SubVIs sssseeeeeeseseeeesseesreeeee Chapter 3 LabVIEW Environment Controls Paletten rarene renen a EE EEK ERE E Functions Palette neee arne E E Ea Navigating the Controls and Functions Palettes 00 0 eee TOols Palettes i cistsictess iealeaeeds E A E E E aides ee evens SHOrtCUb MENUS esanian ena i ri Shortcut Menus in Run Mode ceeeeeee TOODA aeea e aa aa e eh aes ede National Instruments Corporation v LabVIEW User Manual Contents Customizing Your Work Environment 0 cece eceeseescceeeeeeeseceeeesesseenseseeeeaeeseeeaees 3 4 Customizing the Controls and Functions Palettes ccccceceeeeseseeseeeeeee 3 4 Adding VIs and Controls to the User Library and the Instrument PAD Aly eiin o p e i a EE EAE EE 3 4 Creating and Editing Palette Views s s ssssesesessesesesesssseseseserssesses 3 5 How LabVIEW Stores Views cece eeceeeeeeeeseeeeeeneeeeees 3 5 Building ActiveX Subp
3. National Instruments Corporation 15 1 LabVIEW User Manual Chapter 15 Customizing VIs waiting for another operation to complete configure the VI to run at time critical highest priority Refer to the Using LabVIEW to Create Multithreaded VIs for Maximum Performance and Reliability Application Note for more information about creating multithreaded VIs Customizing Menus You can create custom menus for every VI you build and you can configure VIs to show or hide menu bars Show and hide menu bars by selecting File VI Properties selecting Windows Appearance from the Category pull down menu clicking the Customize button and placing or removing a checkmark from the Show Menu Bar checkbox Configuring menus includes creating the menu and providing the block diagram code that executes when the user selects the various menu items 3 Note Custom menus appear only while the VI runs Creating Menus LabVIEW User Manual You can build custom menus or modify the default LabVIEW menus statically when you edit the VI or programmatically when you run the VI When you select Edit Run Time Menu and create a menu in the Menu Editor dialog box LabVIEW creates a run time menu rtm file so you can have a custom menu bar on a VI rather than the default menu bar After you create and save the rtm file you must maintain the same relative path between the VI and the rtm file Use the Menu Editor dialog box to associate a custom rtm
4. Nodes are objects on the block diagram that have inputs and or outputs and perform operations when a VI runs They are analogous to statements operators functions and subroutines in text based programming languages The Add and Subtract functions in Figure 2 2 are nodes Refer to the Block Diagram Nodes section of Chapter 5 Building the Block Diagram for more information about nodes You transfer data among block diagram objects through wires In Figure 2 2 wires connect the control and indicator DBL terminals to the Add and Subtract functions Each wire has a single data source but you can wire it to many VIs and functions that read the data Wires are different colors styles and thicknesses depending on their data types A broken wire appears as a dashed black line Refer to the Using Wires to Link Block Diagram Objects section of Chapter 5 Building the Block Diagram for more information about wires Structures are graphical representations of the loops and case statements of text based programming languages Use structures on the block diagram to repeat blocks of code and to execute code conditionally or in a specific order Refer to Chapter 8 Loop and Case Structures for examples and more information about structures Icon and Connector Pane LabVIEW User Manual After you build a VI front panel and block diagram build the icon and the connector pane so you can use the VI as a subVI Every VI displays an icon such as t
5. 1ib e instr 1ib Any instrument driver VI that you want to appear on the Instrument I O Instrument Drivers palette e project vVIs you use to extend LabVIEW capabilities VIs you store in this directory appear on the Tools menu e www Location of HTML files you can access through the Web Server e help Any VIs PDFs and h1p files that you want to make available on the Help menu You also can create a directory anywhere on your hard drive to store LabVIEW files that you create Refer to the Saving VIs section of Chapter 7 Creating VIs and SubVIs for more information about creating directories National Instruments Corporation A 3 LabVIEW User Manual Polymorphic Functions Functions are polymorphic to varying degrees none some or all of their inputs can be polymorphic Some function inputs accept numerics or Boolean values Some accept numerics or strings Some accept not only scalar numerics but also arrays of numerics clusters of numerics arrays of clusters of numerics and so on Some accept only one dimensional arrays although the array elements can be of any type Some functions accept all types of data including complex numerics Refer to the Polymorphic Units in LabVIEW Application Note for more information about creating and using polymorphic units For more information Refer to the LabV EW Help for more information about polymorphic functions Numeric Conversion You can convert any
6. PDF library 1 1 performance disabling debugging tools 6 6 local and global variables 10 4 options 3 6 phone technical support E 2 picture controls and indicators data type table 5 3 using 12 1 picture ring controls 4 13 pictures See graphics pipes communication 17 15 pixmaps 12 5 planning projects 7 1 plots adding to graphs and charts See the LabVIEW Help anti aliased 11 2 overlaid 11 6 stacked 11 6 PNG files 12 6 14 4 Web Server 17 10 polar graphs 12 3 ni com polymorphic controls and indicators data type table 5 3 Expression Nodes 20 4 functions B 1 units B 1 VIs 5 13 building 5 14 editing shortcut menus See the LabVIEW Help removing subVIs from See the LabVIEW Help selecting a default instance See the LabVIEW Help pop up menus See shortcut menus Portable Network Graphics files 12 6 porting VIs 7 12 PostScript printing See the LabVIEW Help PPC Toolbox 17 15 preferences See options previous versions saving VIs 7 11 printing 14 5 active window 14 5 at completion 14 6 documentation of VIs 14 3 options 3 6 programmatically 14 6 reports 14 5 saving to HTML 14 3 to RTF 14 3 techniques 14 7 using subVIs 14 7 Probe tool debugging VIs 6 4 programming examples E 1 program to program communication 17 15 project design 7 1 project planning 7 1 National Instruments Corporation Index properties ActiveX 18 1 setting 18 4 programmatica
7. Reading data from and writing data to files Reading from and writing to spreadsheet formatted files Moving and renaming files and directories Changing file characteristics Creating modifying and reading a configuration file Use the high level VIs to perform common I O operations Use the low level VIs and functions to control each file I O operation individually For more information Refer to the LabVIEW Help for more information about performing file 1 0 operations Basics of File 1 0 A typical file I O operation involves the following process 1 Create or open a file Indicate where an existing file resides or where you want to create a new file by specifying a path or responding to a dialog box to direct LabVIEW to the file location After the file opens a refnum represents the file Refer to the References to Objects or Applications section of Chapter 4 Building the Front Panel for more information about refnums Read from or write to the file Close the file Most File I O VIs and functions perform only one step in a file I O operation However some high level File I O VIs designed for common file National Instruments Corporation 13 1 LabVIEW User Manual Chapter 13 File 1 0 I O operations perform all three steps Although these VIs are not always as efficient as the low level functions you might find them easier to use Choosing a File 1 0 Format The File I O VIs you use depend o
8. Refer to the LabVIEW Help for more information about documenting and printing VIs Documenting Vis You can use LabVIEW to track development document a finished VI and create instructions for users of VIs You can view documentation within LabVIEW print it and save it to HTML or RTF files ay Note You cannot print VI documentation in any format in built applications To use printed documentation most effectively create VI and object descriptions and set up the VI revision history National Instruments Corporation 14 1 LabVIEW User Manual Chapter 14 Documenting and Printing Vis Creating VI and Object Descriptions Create descriptions for VIs and their objects such as controls and indicators to describe the purpose of the VI or object and to give users instructions for using the VI or object You can view the descriptions in LabVIEW or print them Create edit and view VI descriptions by selecting File VI Properties and selecting Documentation from the Category pull down menu Create edit and view object descriptions by right clicking the object and selecting Description and Tip from the shortcut menu Tip strips are brief descriptions that appear when you move the cursor over an object If you do not enter a tip in the Description and Tip dialog box no tip strip appears The VI or object description appears in the Context Help window when you move the cursor over the VI icon or object respectively Select Help S
9. Replace File vi Close Filej Figure 13 2 Using a Low Level VI to Write to a Spreadsheet Compare the VI in Figure 13 2 to the VI in Figure 13 1 which completes the same task In Figure 13 2 you have to use the Array To Spreadsheet String function to format the array of numbers as a string The Write To Spreadsheet File VI in Figure 13 1 opens the file converts the array of numbers to a string and closes the file Refer to the Write Datalog File Example VI in the examples file datalog 11b for an example of using low level file I O VIs and functions Disk Streaming You also can use the low level File I O VIs and functions for disk streaming which saves memory resources Disk streaming is a technique for keeping files open while you perform multiple write operations for example within a loop Although the high level write operations are easy to use they add the overhead of opening and closing the file each time they execute Your VIs can be more efficient if you avoid opening and closing the same files frequently Disk streaming reduces the number of times the function interacts with the operating system to open and close the file To create a typical disk streaming operation place the Open Create Replace File VI before the loop and the Close File function after the loop Continuous writing to a file then can occur within the loop without the overhead associated with opening and closing the file Disk streaming is i
10. Use the Open VI Reference function to access a VI on the local or remote computer e Property Node Gets and sets VI or application properties Refer to the Property Nodes section of this chapter for more information about properties e Invoke Node Invokes methods on a VI or application Refer to the Invoke Nodes section of this chapter for more information about methods e Call By Reference Node Dynamically calls the referenced VI e Close LV Object Reference Closes the refnum to the VI or application you accessed using the VI Server 16 2 ni com Chapter 16 Programmatically Controlling VIs Application and VI References You access VI Server functionality through references to two main classes of objects the Application object and the VI object After you create a reference to one of these objects you can pass the reference to a VI or function that performs an operation on the object An Application refnum refers to a local or remote instance of LabVIEW You can use Application properties and methods to change LabVIEW preferences and return system information A VI refnum refers to a VI in the instance of LabVIEW With a refnum to an instance of LabVIEW you can retrieve information about the LabVIEW environment such as the platform on which LabVIEW is running the version number or a list of all VIs currently in memory You also can set information such as the current user name or the list of VIs exported to other i
11. You also can use it to display but not modify the data Refer to the Handling Variant Data section of Chapter 5 Building the Block Diagram for more information about variant data 18 2 ni com Chapter 18 ActiveX LabVIEW as an ActiveX Client When LabVIEW accesses the objects associated with another ActiveX enabled application it is acting as an ActiveX client You can use LabVIEW as an ActiveX client in the following ways e Open an application such as Microsoft Excel create a document and add data to that document Embed a document such as a Microsoft Word document or an Excel spreadsheet on the front panel e Place a button or other object from another application such as a Help button that calls the other application help file on the front panel e Linkto an ActiveX control you built with another application LabVIEW accesses an ActiveX object with the automation refnum control and the ActiveX container both of which are front panel objects Use the automation refnum control to select an ActiveX object Use the ActiveX container to select a displayable ActiveX object such as a button or document and place it on the front panel Both objects appear as automation refnum controls on the block diagram Accessing an ActiveX Enabled Application To access an ActiveX enabled application use the automation refnum control on the block diagram to create a reference to an application Wire the control to the Automation
12. You can compile the individual HTML files LabVIEW generates into an HTML Help file You can compile the RTF files LabVIEW generates into a Windows WinHelp Macintosh QuickHelp or UNIX HyperHelp file 14 4 ni com Chapter 14 Documenting and Printing VIs Create links from VIs to HTML files or compiled help files by selecting File VI Properties and selecting Documentation from the Category pull down menu Printing Vis You can use the following primary methods to print VIs in LabVIEW e Select File Print Window to print the contents of the active window e Select File Print to print more comprehensive information about a VI including information about the front panel block diagram subVIs controls VI history and so on Refer to the Printing Documentation section of this chapter for more information about using this method to print VIs e Use the Report Generation VIs to print paper reports or to save HTML reports of the information the VI generates e Use the VI Server to programmatically print any VI window or VI documentation at any time Refer to Chapter 16 Programmatically Controlling VIs for more information about using this method to print VIs Printing the Active Window Select File Print Window to print the contents of the active front panel or block diagram window with the minimum number of prompts LabVIEW prints the workspace of the active window but is not limited by the active window size LabVIEW
13. backslash codes If you change the data type of the wire connected to the selector terminal of a Case structure the Case structure automatically converts the case selector values to the new data type when possible If you convert a numeric value for example 19 to a string the string value is 19 If you convert a National Instruments Corporation 8 7 LabVIEW User Manual Chapter 8 Loop and Case Structures string to a numeric value LabVIEW converts only those string values that represent a number The other values remain strings If you convert a number to a Boolean value LabVIEW converts 0 to FALSE and 1 to TRUE and all other numeric values become strings If you enter a selector value that is not the same type as the object wired to the selector terminal the value appears red to indicate that you must delete or edit the value before the structure can execute and the VI will not run Also because of the possible round off error inherent in floating point arithmetic you cannot use floating point numerics as case selector values If you wire a floating point value to the case LabVIEW rounds the value to the nearest even integer If you type a floating point value in the case selector label the value appears red to indicate that you must delete or edit the value before the structure can execute Input and Output Tunnels You can create multiple input and output tunnels for a Case structure Inputs are available to all cases
14. but cases do not need to use each input However you must define each output tunnel for each case When you create an output tunnel in one case tunnels appear at the same position on the border in all the other cases If at least one output tunnel is not wired all output tunnels on the structure appear as white squares You can define a different data source for the same output tunnel in each case but the data types must be compatible for each case You also can right click the output tunnel and select Use Default If Unwired from the shortcut menu to use the default value for the tunnel data type for all unwired tunnels Using Case Structures for Error Handling When you wire an error cluster to the Selector terminal of a Case structure the case selector label displays two cases Error and No Error and the border of the Case structure changes color red for Error and green for No Error The Case structure executes the appropriate case subdiagram based on the error state Refer to the Error Handling section of Chapter 6 Running and Debugging VIs for more information about handling errors Sequence Structures LabVIEW User Manual A Sequence structure shown at left contains one or more subdiagrams or frames which execute in sequential order The frame label at the top of the Sequence structure is similar to the case selector label of the Case structure The frame label contains the frame number in the center and decrement and incre
15. data from new data Set of rules to which statements must conform in a particular programming language Transmission Control Protocol Object or region on a node through which data pass Small yellow text banners that identify the terminal name and make it easier to identify terminals for wiring Special cursor to perform specific operations Bar that contains command buttons to run and debug VIs Palette that contains tools you can use to edit and debug front panel and block diagram objects VI at the top of the VI hierarchy This term distinguishes the VI from its subVIs Data entry or exit terminal on a structure G 14 ni com two dimensional type definition U UDP universal constant user defined constant V vector VI VI class VI library VI Server virtual instrument VI Virtual Instrument Software Architecture VISA VXI National Instruments Corporation G 15 Glossary Having two dimensions as in the case of an array that has several rows and columns Master copy of a custom object that several VIs can use User Datagram Protocol Uneditable block diagram object that emits a particular ASCII character or standard numeric constant for example 7 Block diagram object that emits a value you set 1D array See virtual instrument VI A reference to a virtual instrument that allows access to VI properties and methods Special file that contains a collection of relat
16. rectangles to assign inputs and outputs The number of terminals LabVIEW displays on the connector pane depends on the number of controls and indicators on the front panel The connector pane has at most 28 terminals If your front panel contains more than 28 controls and indicators that you want to use programmatically group some of them into a cluster and assign the cluster to a terminal on the connector pane Refer to the Clusters section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about grouping data using clusters Sy Note Try not to assign more than 16 terminals to a VI Too many terminals can reduce the readability and usability of the VI LabVIEW User Manual Select a different terminal pattern for a VI by right clicking the connector pane and selecting Patterns from the shortcut menu Select a connector pane pattern with extra terminals You can leave the extra terminals unconnected until you need them This flexibility enables you to make changes with minimal effect on the hierarchy of the VIs If you create a group of subVIs that you use together often give the subVIs a consistent connector pane with common inputs in the same location to help you remember where to locate each input If you create a subVI that produces an output another subVI uses as the input align the input and output connections to simplify the wiring patterns Place the error in 7 6 ni com Chapter 7 Creating Vis
17. suppose you are a bookseller who sells books on the Web You want to classify each book in your library by the following criteria e Type of book fiction or nonfiction e Title National Instruments Corporation 9 5 LabVIEW User Manual Chapter 9 Grouping Data Using Strings Arrays and Clusters LabVIEW User Manual e Author e Publisher e Price e Genre s e Synopsis e Number of pages You can create an XML file for each book The XML file for a book titled Touring Germany s Great Cathedrals would be similar to the following lt nonfiction gt lt Title gt Touring Germany s Great Cathedrals lt Title gt lt Author gt Tony Walters lt Author gt lt Publisher gt Douglas Drive Publishing lt Publisher gt lt PriceUS gt 29 99 lt PriceUS gt lt Genre gt Travel lt Genre gt lt Genre gt Architecture lt Genre gt lt Genre gt History lt Genre gt lt Synopsis gt This book fully illustrates twelve of Germany s most inspiring cathedrals with full color photographs scaled cross sections and time lines of their construction lt Synopsis gt lt Pages gt 224 lt Pages gt lt nonfiction gt Similarly you can classify LabVIEW data by name value and type You can represent a string control for a user name in XML as follows lt String gt lt Name gt User Name lt Name gt lt Value gt Reggie Harmon lt Value gt lt String gt Using XML Based Data Types Converting LabVIEW data to XML formats
18. terminals unassigned Refer to the Setting up the Connector Pane section of Chapter 7 Creating VIs and SubVIs for more information about setting up connector panes 3 Note Try not to assign more than 16 terminals to a VI Too many terminals can reduce the readability and usability of the VI Using and Customizing Vis and SubVis After you build a VI and create its icon and connector pane you can use it as a subVI Refer to the SubVIs section of Chapter 7 Creating VIs and SubVIs for more information about subVIs You can save VIs as individual files or you can group several VIs together and save them in a VI library Refer to the Saving VIs section of Chapter 7 Creating VIs and SubVIs for more information about saving VIs in libraries You can customize the appearance and behavior of a VI You also can create custom menus for every VI you build and you can configure VIs to show or hide menu bars Refer to Chapter 15 Customizing VIs for more information about customizing a VI National Instruments Corporation 2 5 LabVIEW User Manual LabVIEW Environment Use the LabVIEW palettes tools and menus to build the front panels and block diagrams of VIs You can customize the Controls and Functions palettes and you can set several work environment options For more information Refer to the LabV EW Help for more information about using the palettes menus and toolbar and customizing your work environment Co
19. variable to terminate the loops Creating Global Variables LabVIEW User Manual Select Functions Structures Global Variable and place a global variable shown at left on the block diagram Double click the global variable node to display the front panel of the global VI Place controls and indicators on this front panel the same way you do on a standard front panel 10 2 ni com Chapter 10 Local and Global Variables LabVIEW uses owned labels to identify global variables so label the front panel controls and indicators with descriptive owned labels Refer to the Labeling section of Chapter 4 Building the Front Panel for more information about owned and free labels You can create several single global VIs each with one front panel object or you can create one global VI with multiple front panel objects A global VI with multiple objects is more efficient because you can group related variables together The block diagram of a VI can include several global variable nodes that are associated with controls and indicators on the front panel of a global VI These global variable nodes are either copies of the first global variable node that you placed on the block diagram of the global VI or they are the global variable nodes of global VIs that you placed on the current VI You place global VIs on other VIs the same way you place subVIs on other VIs Each time you place a new global variable node on a block diagram Lab VIEW creates
20. 1 classic controls and indicators 4 7 clearing graphs and charts See the LabVIEW Help indicators See the LabVIEW Help clients ActiveX 18 3 LabVIEW for remote front panels 17 12 multiple for remote front panels 17 11 Web browser for remote front panels 17 12 cloning objects on front panel or block diagram See the LabVIEW Help clusters 9 13 comparing C 2 controls and indicators 4 11 data type table 5 3 LabVIEW User Manual l 4 converting arrays to and from See the LabVIEW Help error 6 9 components 6 10 reports See the LabVIEW Help functions 5 7 moving See the LabVIEW Help order of elements 9 14 modifying 9 14 See also the LabVIEW Help polymorphism B 6 resizing See the LabVIEW Help wire patterns 9 14 Code Interface Node 19 1 coercion dots 5 12 color boxes 4 9 creating in graphics 12 6 high color controls and indicators 4 7 low color controls and indicators 4 7 mapping 11 12 modifying in graphics 12 6 options 3 6 picker 4 9 ramps 4 9 rotary controls and indicators 4 9 coloring background objects See the LabVIEW Help defining user colors See the LabVIEW Help foreground objects See the LabVIEW Help front panel objects 4 4 copying colors See the LabVIEW Help system colors 4 19 See also the LabVIEW Help transparent objects See the LabVIEW Help ni com command line launching VIs See the LabVIEW Help commenting out sections of a block diagram debugging VIs 6
21. 2D array and you wire only the row input you extract a complete 1D row of the array If you wire only the column input you extract a complete 1D column of the array If you wire the row input and the column input you extract a single element of the array Each input group is independent and can access any portion of any dimension of the array The block diagram shown in Figure 9 9 uses the Index Array function to retrieve a row and an element from a 2D array o Index row Index row Index col Figure 9 9 Indexing a 2D Array To access multiple consecutive values in an array expand the Index Array function but do not wire values to the index inputs in each increment For example to retrieve the first second and third rows from a 2D array expand the Index Array function by three increments and wire 1D array indicators to each sub array output Clusters Clusters group data elements of mixed types such as a bundle of wires as in a telephone cable where each wire in the cable represents a different element of the cluster A cluster is similar to a record or a struct in text based programming languages National Instruments Corporation 9 13 LabVIEW User Manual Chapter 9 Grouping Data Using Strings Arrays and Clusters LabVIEW User Manual Bundling several data elements into clusters eliminates wire clutter on the block diagram and reduces the number of connector pane terminals that subVIs ne
22. 4 13 Advanced Enumerated Type Controls and Indicators 4 13 I O Name Controls and Indicators eee eseceeeseeeseeseceecesecneeesesneeeaeeeaes 4 14 Waveform Control sisne eecteceen ds cehecieadessivreeads n a ees ai 4 15 References to Objects or Applications seesessessesssesrestsrsresreerrsrsrrsrsrsersresee 4 15 Dialog Controls soiisisns tosissanne iin E a aa is 4 15 Labeling seno ana E R E A E R E a a a neeeeed 4 16 Caption S iino isien hse EEN e VAEA E E E ee ee el eee 4 16 Text Characteristics e nanea rria ar nrar aa Ea anao aa EEE EE aE E Eaa 4 17 Designing User Interfaces nennir oi ra EAE E 4 18 Using Front Panel Controls and Indicators 00 0 eee eeeeseeeeeeeeeeeeseeeees 4 18 Designing Dialog Boxes eee ee eeceeseceeceseseeeesecseeeaeeseeeaececesecseseaesseseaeesees 4 19 Selecting the Screen S1Ze s i e sssetessiscaseclasestesasaases seciessedespiveagedssnecduscsbsacusescdde 4 19 Chapter 5 Building the Block Diagram Relationship between Front Panel Objects and Block Diagram Terminals 5 1 Block Diagram Objects 24 6 waist antec heated wah ules ends A 5 1 Block Diagram Terminals orcii a E 5 1 Control and Indicator Data Types 0 0 eee eeeseceeeseeneeseeeeeeseeeees 5 2 Constants ss n licen e E vce oneets cos EE E AER 5 4 Universal Constant 0 cece eeceeseeceseseeeeeseeeeseeseeeaeeseees 5 4 User Defined Constant eee ceceeeeeceseceeeeeeseeeaeeeeees 5 4 Block Diagram Nodes sccssccg
23. 6 communication 17 1 ActiveX 18 1 Apple events 17 15 DataSocket 17 2 DDE 17 15 executing system level commands 17 15 file I O 13 1 functions 7 3 low level 17 14 Macintosh 17 15 pipes 17 15 PPC 17 15 protocols 17 14 System Exec VI 17 15 TCP 17 14 UDP 17 14 UNIX 17 15 VI Server 16 1 VIs 7 3 compacting memory See the LabVIEW Help comparing arrays C 2 Boolean values C 1 clusters C 2 numerics C 2 strings C 1 versions of VIs 7 2 Comparison functions C 1 polymorphism B 6 computer based instruments configuring 1 3 conditional terminals 8 2 configuration file VIs format 13 13 purpose 13 13 reading and writing ini files 13 12 National Instruments Corporation l 5 Index configuring front panel objects 4 1 menus 15 2 servers for remote front panels 17 11 LabVIEW 17 12 Web browser 17 12 VI appearance and behavior 15 1 connecting terminals 5 10 connector panes 2 4 printing 14 3 required and optional inputs and outputs 7 7 setting up 7 6 constants 5 4 arrays 9 11 creating See the LabVIEW Help editing See the LabVIEW Help setting parameters with ActiveX 18 6 universal 5 4 user defined 5 4 consulting services E 1 contacting National Instruments E 2 containers ActiveX 18 2 continuously running VIs 6 1 control flow programming model 5 20 control references 16 8 creating See the LabVIEW Help strictly typed 16 9 weakly typed 16 9 controlling front panel o
24. 8 writing numeric data to 9 5 stacked plots 11 6 stacks variant data 5 17 stand alone applications building 7 12 distributing VIs 7 12 statements See nodes static front panel images 17 10 static variables See shift registers stepping through VIs debugging VIs 6 4 storing work environment options 3 6 strict type checking 5 18 strictly typed refnums control 16 9 VI 16 7 strings 9 1 comparing C 1 controls data type table 5 2 controls and indicators 4 10 display types 9 2 editing programmatically 9 3 formatting 9 4 specifiers 9 4 functions 5 7 global variables 10 5 numerics to 9 5 polymorphism B 5 replacing text See the LabVIEW Help splitting See the LabVIEW Help tables 9 2 universal constants 5 4 strip chart 11 6 LabVIEW User Manual 1 24 structure and support directory menus A 2 project A 2 resource A 2 templates A 2 WWW A 2 structure of LabVIEW directories A 1 structures 8 1 Case 8 6 debugging See the LabVIEW Help deleting See the LabVIEW Help Event 8 12 For Loops 8 2 global variables 10 2 local variables 10 1 on block diagram 2 4 removing See the LabVIEW Help Sequence 8 8 using See the LabVIEW Help While Loops 8 2 wiring See the LabVIEW Help subpalettes building ActiveX 3 5 creating See the LabVIEW Help moving See the LabVIEW Help organizing 3 5 subroutines See subVIs subVIs 7 4 building 7 4 control captions for tip strips See the Lab
25. A VI within another VI is called a subVI A subVI corresponds to a subroutine in text based programming languages For more information Refer to the LabVIEW Help for more information about creating Vis and subVIs Front Panel The front panel is the user interface of the VI Figure 2 1 shows an example of a front panel National Instruments Corporation 2 1 LabVIEW User Manual Chapter 2 Introduction to Virtual Instruments p gt O01 gfpan vi File Edit Operate Tools Browse Window Help Continuous 20 a 80 202 A STE Lm eeno Waveform Ees 10 0 G0 8 0 6 0 40 60 4 0 0 0 0 00 0 0 0 Figure 2 1 Example of a Front Panel You build the front panel with controls and indicators which are the interactive input and output terminals of the VI respectively Controls are knobs push buttons dials and other input devices Indicators are graphs LEDs and other displays Controls simulate instrument input devices and supply data to the block diagram of the VI Indicators simulate instrument output devices and display data the block diagram acquires or generates Refer to Chapter 4 Building the Front Panel for more information about the front panel Block Diagram LabVIEW User Manual After you build the front panel you add code using graphical representations of functions to control the front panel objects The block diagram contains this graphical source code Fr
26. A black arrow button appears when all subVIs are displayed National Instruments Corporation 7 9 LabVIEW User Manual Chapter 7 Creating Vis and SubVIs Saving VIs You can save VIs as individual files or you can group several VIs together and save them in a VI library VI library files end with the extension 11b National Instruments recommends that you save VIs as individual files organized in directories especially if multiple developers are working on the same project Advantages of Saving Vis as Individual Files The following list describes reasons to save VIs as individual files e You can use the file system to manage the individual files e You can use subdirectories e You can store VIs and controls in individual files more robustly than you can store your entire project in the same file e You can use the Professional Development System built in source code control tools or third party source code control tools Advantages of Saving VIs as Libraries The following list describes reasons to save VIs as libraries e You can use up to 255 characters to name your files Macintosh MacOS 9 x or earlier limits you to 31 characters for filenames but has no limit on characters for library names e You can transfer a VI library to other platforms more easily than you can transfer multiple individual VIs e You can slightly reduce the file size of your project because VI libraries are compressed to reduce disk space
27. Arrays and Clusters for more information about using the Array functions Use the Cluster functions located on the Functions Cluster palette to create and manipulate clusters such as the following tasks e Extract individual data elements from a cluster e Add individual data elements to a cluster e Break a cluster out into its individual data elements Refer to the Clusters section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about using the Cluster functions National Instruments Corporation 5 7 LabVIEW User Manual Chapter 5 Building the Block Diagram Comparison Functions Use the Comparison functions located on the Functions Comparison palette to compare Boolean values strings numerics arrays and clusters Refer to Appendix C Comparison Functions for more information about using the Comparison functions Time and Dialog Functions File 1 0 Functions Use the Time and Dialog functions located on the Functions Time amp Dialog palette to perform the following tasks e Manipulate the speed at which an operation executes e Retrieve time and date information from your computer clock e Create dialog boxes to prompt users with instructions This palette also includes the Error Handler VIs Refer to the Error Checking and Error Handling section of Chapter 6 Running and Debugging VIs for more information about using the Error Handler VIs Use the File I O function
28. Binary File VIs in the examples file smplfile 11b for examples of reading and writing an array of double precision floating point values to and from a binary file respectively When to Use Datalog Files LabVIEW User Manual Use datalog files to access and manipulate data only in LabVIEW and to store complex data structures quickly and easily Datalog files are files only LabVIEW can create and read Unlike binary files that require similar data types when storing you can use datalog files to store several different data types in one record of a file For example in one datalog file you can store strings numerics and clusters A datalog file stores data as a sequence of identically structured records similar to a spreadsheet where each row represents a record Each record in a datalog file must have the same data types associated with it LabVIEW writes each record to the file as a cluster containing the data to store However the components of a datalog record can be any data type which you determine when you create the file For example you can create a datalog whose record data type is a cluster of a string and a number Then each record of the datalog is a cluster of a string and a number However the first record could be abc 1 while the second record could be xyz 7 Using datalog files requires little manipulation which makes writing and reading much faster It also simplifies data retrieval because
29. Communication HiQ palette to control HiQ from LabVIEW and transfer data between the two applications in various formats You must install HiQ to use these VIs Use these HiQ VIs to launch HiQ access and manipulate HiQ Notebooks to analyze and visualize data and run a HiQ Script within a Notebook Refer to the HiQ Help for more information about HiQ functionality including the mathematical features function reference and syntax information Refer to examples comm hig for examples of setting up and using the HiQ VIs HiQ and MATLAB Script Nodes Use the HiQ and MATLAB script nodes located on the Functions Mathematics Formula palette to load and edit HiQ and MATLAB scripts on the block diagram so LabVIEW can work with their advanced mathematics functionality You must have HiQ or MATLAB installed to use script nodes If you already have a script written in HiQ or MATLAB you can import it into the script node You assign script node terminals as inputs or outputs for the variables in the script to pass values between HiQ or MATLAB and LabVIEW You can determine the function of a terminal by the way the equation is written For example if the script contains the assignment statement X i 3 you can assign ij as an input terminal to control how the script node calculates X and you can assign X to an output terminal to retrieve the final result of the script calculation If you do not already have a script written you can pl
30. E Technical Support Resources Glossary Index LabVIEW User Manual xvi ni com About This Manual This manual describes the LabVIEW graphical programming environment and techniques for building applications in LabVIEW such as test and measurement data acquisition instrument control datalogging measurement analysis and report generation applications Use this manual to learn about LabVIEW programming features including the LabVIEW user interface and programming work spaces and the LabVIEW palettes tools and dialog boxes This manual does not include specific information about each palette tool menu dialog box control or built in VI or function Refer to the LabVIEW Help for more information about these items and for detailed step by step instructions for using LabVIEW features and for building specific applications Refer to the LabVIEW Documentation Resources section of Chapter 1 Introduction to LabVIEW for more information about the LabVIEW Help and accessing it The LabVIEW User Manual is also available in Portable Document Format PDF If you select the Complete install option Lab VIEW installs PDF versions of all LabVIEW manuals which you can access by selecting Help Search the LabVIEW Bookshelf in LabVIEW Sy Note You must have Adobe Acrobat Reader 4 0 or later installed to view the PDFs Refer to the Adobe Systems Incorporated Web site at www adobe com to download Acrobat Reader You can access the PDFs f
31. Library Function Node to call most standard shared libraries or DLLs With this function you can create an interface in LabVIEW to call existing libraries or new libraries specifically written for use with LabVIEW National Instruments recommends using the Call Library Function Node to create an interface to external code Code Interface Node Use the CIN as an alternative method for calling source code written in C The Call Library Function Node generally is easier to use than the CIN National Instruments Corporation 19 1 LabVIEW User Manual Formulas and Equations When you want to use a complicated equation in LabVIEW you do not have to wire together various arithmetic functions on the block diagram You can develop equations in a familiar mathematical environment and then integrate the equations into an application Use the Formula Node and Expression Node to perform mathematical operations in the LabVIEW environment For more advanced functionality you can link to the mathematics applications HiQ and MATLAB to develop equations HiQ and MATLAB are software packages that help you organize and visualize real world math science and engineering problems For more information Refer to the LabVIEW Help for more information about using equations and the syntax to use available functions and operators and descriptions of possible errors Methods for Using Equations in LabVIEW 3 You can use the Formula
32. Open function which opens the calling application Use the Property Node to select and access the properties associated with the object Use the Invoke Node to select and access the methods associated with the object Close the reference to the object using the Automation Close function Closing the reference removes the object from memory For example you can build a VI that opens Microsoft Excel so it appears on the user s screen creates a workbook creates a spreadsheet creates a table in LabVIEW and writes that table to the Excel spreadsheet Refer to the Write Table To XL VI in the examples comm ExcelExamples 11b for an example of using LabVIEW as an Excel client 3 Note Applications that include ActiveX custom interfaces appear with a E icon Click the icon to select an object for the custom interface Refer to the Support for Custom ActiveX Automation Interfaces section in this chapter for more information about custom interfaces National Instruments Corporation 18 3 LabVIEW User Manual Chapter 18 ActiveX Inserting an ActiveX Object on the Front Panel To insert an ActiveX control on the front panel use the ActiveX container to select the ActiveX object or document and access the properties and methods associated with that object You can set the properties for an ActiveX object using the ActiveX Property Browser or property pages or you can set the properties programmatically using the Property Node Refer to the Se
33. Toolbox is the best method to send large amounts of information between applications that support PPC Toolbox Refer to the Using Apple Events and the PPC Toolbox to Communicate with LabVIEW Applications on the Macintosh Application Note for more information about using Apple events and PPC Toolbox in LabVIEW applications Use the Pipe VIs to open close read and write to UNIX named pipes Use named pipes to communicate between LabVIEW and unrelated processes Executing System Level Commands Windows and UNIX Use the System Exec VI to execute or launch other Windows applications or UNIX command line applications from within VIs With the System Exec VI you execute a system level command line that can include any parameters supported by the application you want to launch National Instruments Corporation 17 15 LabVIEW User Manual ActiveX With ActiveX Automation a Windows application such as LabVIEW provides a public set of objects commands and functions that other Windows applications can access You can use LabVIEW as an ActiveX client to access the objects properties methods and events associated with other ActiveX enabled applications LabVIEW also can act as an ActiveX server so other ActiveX enabled applications can access LabVIEW objects properties and methods In this manual ActiveX refers to Microsoft s ActiveX technology and OLE technology This technology is available only on Windows Refer to the Micr
34. Use the Smith Plot VIs to display impedances of transmission lines The plot consists of circles of constant resistance and reactance You can plot a given impedance r jx by locating the intersection of the appropriate r circle and x circle After you plot the impedance use the Smith Plot VIs as visual aids to match impedance and to calculate the reflection coefficient of a transmission line The Smith Plot VIs provide a large amount of functionality in each single VI Consequently many of these VIs include complicated clusters for inputs You can use default values and custom controls to decrease the complexity of the VIs Instead of creating your own cluster input copy a custom control from the Smith Plot example VIs in the examples picture demos 11b and place it on your front panel If you are graphing load impedances you can represent an impedance as a complex number of the form r jx To avoid losing detail in the Smith plot use the Normalize Smith Plot VI to normalize the data You can pass the data you normalize with the Normalize Smith Plot VI directly to the Smith Plot VI You usually scale Smith plot data with respect to the characteristic impedance Zp of the system 12 4 ni com Chapter 12 Graphics and Sound VIs Picture Functions VIs Use the Picture Functions VIs located on the Functions Graphics amp Sound Picture Functions palette to draw shapes and enter text into a picture indicator You can draw point
35. VI itself or programmatically by using the VI Server Refer to Chapter 16 Programmatically Controlling VIs for more information about using the VI Server to configure several VIs to behave identically For more information Refer to the LabVIEW Help for more information about customizing VIs Configuring the Appearance and Behavior of Vis Select File VI Properties to configure the appearance and behavior of a VI Use the Category pull down menu at the top of the dialog box to select from several different option categories including the following e General Displays the current path where a VI is saved its revision number revision history and any changes made since the VI was last saved You also can use this page to edit an icon Documentation Use this page to add a description of the VI and link to a help file topic Refer to the Documenting VIs section of Chapter 14 Documenting and Printing VIs for more information about the documentation options Security Use this page to lock or password protect a VI Window Appearance Use this page to configure various window settings Window Size Use this page to set the size of the window Execution Use this page to configure how a VI runs For example you can configure a VI to run immediately when it opens or to pause when called as a subVI You also can configure the VI to run at different priorities For example if it is crucial that a VI runs without
36. VI or library You might notice a problem in a VI or a system program Error Handling LabVIEW does not handle errors automatically Instead you choose the error handling method you want to use For example if an I O VI on the block diagram times out you might not want the entire application to stop You also might want the VI to retry for a certain period of time In LabVIEW you can make these error handling decisions on the block diagram of the VI VIs and functions return errors in one of two ways with numeric error codes or with an error cluster Typically functions use numeric error codes and VIs use an error cluster usually with error inputs and outputs Refer to the Error Clusters section of this chapter for more information about error clusters Error handling in LabVIEW follows the dataflow model Just as data flow through a VI so can error information Wire the error information from the beginning of the VI to the end Include an error handler VI at the end of the VI to determine if the VI ran without errors Use the error in and error out National Instruments Corporation 6 9 LabVIEW User Manual Chapter 6 Running and Debugging VIs LabVIEW User Manual clusters in each VI you use or build to pass the error information through the VI As the VI runs Lab VIEW tests for errors at each execution node If LabVIEW does not find any errors the node executes normally If LabVIEW detects an error the node passes the e
37. a carriage return In addition Lab VIEW stores backslash characters in the configuration settings file as double backslashes such as for Set the read raw string or write raw string inputs of the Configuration File VIs to TRUE for raw data and to FALSE for escaped data When VIs write to a configuration file they place quotation marks around any string or path data that contain a space character If a string contains quotation marks LabVIEW stores them as If you read and or write to configuration files using a text editor you might notice that LabVIEW replaced quotation marks with LabVIEW stores path data in a platform independent format the standard UNIX format for paths in ini files The VIs interpret the absolute path c temp data dat stored in a configuration settings file as follows e Windows c temp data dat e Macintosh c temp data dat e UNIX c temp data dat The VIs interpret the relative path temp data dat as follows e Windows temp data dat e Macintosh temp data dat e UNIX temp data dat 13 14 ni com Chapter 13 File 1 0 Logging Front Panel Data Use front panel datalogging to record data for use in other VIs and in reports For example you can log data from a graph and use that data in another graph in a separate VI Each time a VI runs front panel datalogging saves the front panel data to a separate datalog file which is in the format of delimited text You can retrieve the
38. a new VI associated only with that global variable node and copies of it Refer to the SubVIs section of Chapter 7 Creating VIs and SubVIs for more information about subVIs After you finish placing objects on the global VI front panel save it and return to the block diagram of the original VI You must then select the object in the global VI that you want to access Right click the global variable node and select a front panel object from the Select Item shortcut menu The shortcut menu lists all the front panel objects that have owned labels Read and Write Variables After you create a local or global variable you can read data from a variable or write data to it By default a new variable receives data This kind of variable works as an indicator and is a write local or global When you write new data to the local or global variable the associated front panel control or indicator updates to the new data You also can configure a variable to behave as a data source or a read local or global Right click the variable and select Change To Read from the shortcut menu to configure the variable to behave as a control When this node executes the VI reads the data in the associated front panel control or indicator To change the variable to receive data from the block diagram rather than provide data right click the variable and select Change To Write from the shortcut menu National Instruments Corporation 10 3 LabVIEW User Ma
39. all the LabVIEW manuals and Application Notes Access the LabVIEW Bookshelf by selecting Help Search the LabVIEW Bookshelf e Getting Started with Lab VIEW Use this manual to familiarize yourself with the LabVIEW graphical programming environment and the basic LabVIEW features you use to build data acquisition and instrument control applications e LabVIEW Tutorial Use this tutorial to learn basic LabVIEW concepts The tutorial guides you through several activities to familiarize you with graphical programming Access the LabVIEW National Instruments Corporation 1 1 LabVIEW User Manual Chapter 1 3 3 Introduction to LabVIEW Tutorial by selecting Help VI Function and How To Help or by clicking the LabVIEW Tutorial button in the LabVIEW dialog box LabVIEW Quick Reference Card Use this card to get started with LabVIEW quickly The card describes the LabVIEW palettes and general editing wiring and debugging techniques LabVIEW User Manual Use this manual to learn about LabVIEW programming concepts techniques features VIs and functions you can use to create test and measurement data acquisition instrument control datalogging measurement analysis and report generation applications LabVIEW Help Use this help file as a reference for information about LabVIEW palettes menus tools VIs and functions The LabVIEW Help also includes step by step instructions for using LabVIEW features Access the LabVIEW
40. and SubVIs clusters on the lower left corner of the front panel and the error out clusters on the lower right corner Figure 7 1 shows examples of improperly and properly aligned error clusters J lea e a 1 Improper 2 Proper Figure 7 1 Improperly and Properly Aligned Error Clusters Setting Required Recommended and Optional Inputs and Outputs You can designate which inputs and outputs are required recommended and optional to prevent users from forgetting to wire subVI connections Right click a terminal in the connector pane and select This Connection Is from the shortcut menu A checkmark indicates the terminal setting Select Required Recommended or Optional For terminal inputs required means that the block diagram on which the subVI is dropped will be broken if the required inputs are not wired Required is not available for terminal outputs For terminal inputs and outputs recommended means that the block diagram on which the sub VI is dropped can be run if the input is not wired but the Warnings dialog box will generate a warning that the input has not been wired Optional means that the block diagram on which the subVI is dropped can be run and will not generate any warnings if the terminal input or output is not wired Inputs and outputs of VIs in vi lib are already marked as Required Recommended or Optional LabVIEW sets inputs and outputs of VIs you create to Recommended by de
41. and returns an array or cluster of Boolean values In Compare Aggregates mode the string comparison and array comparison operations follow exactly the same process the string is treated as an array of ASCII characters Some Comparison functions operate only in Compare Aggregates so the shortcut menu options do not appear When comparing multi dimensional arrays each array entered in the function must have the same number of dimensions The Comparison functions that do not have the Compare Aggregates or Compare Elements modes compare arrays the same way as they compare strings one element at a time starting with the first element until they encounter an inequality Compare Elements Mode In Compare Elements mode Comparison functions output an array of Boolean values of the same dimensions as the input arrays Each dimension of the output array is the size of the smaller of the two input arrays in that dimension Along each dimension such as row column or page the functions compare corresponding element values in each input array to produce the corresponding Boolean value in the output array C 2 ni com Appendix C Comparison Functions Compare Aggregates Mode In Compare Aggregates mode comparison functions output a single Boolean result LabVIEW considers corresponding values that appear later in the input arrays as secondary to values appearing later in the input arrays LabVIEW performs the following steps to determine the
42. binding 13 15 changing 13 17 clearing 13 16 logging data See datalogging logging in automatically See the LabVIEW Help login prompt at startup displaying See the LabVIEW Help logos DataSocket protocol 17 3 loops auto indexing 8 4 controlling timing 8 6 For 8 2 infinite 8 3 shift registers 8 5 unexpected data 6 7 using See the LabVIEW Help While 8 2 low level communication 17 14 manual See documentation mapping colors 11 12 marking VIs as top level in libraries See the LabVIEW Help masking digital data 11 15 D 1 mathematics See equations MATLAB ActiveX 20 2 data types 20 6 LabVIEW User Manual Index debugging scripts 20 6 script node 20 5 Measurement amp Automation Explorer 1 3 measurement units 5 17 memory coercion dots 5 12 compacting See the LabVIEW Help deallocating See the LabVIEW Help disabling debugging tools 6 6 global variables 10 5 local variables 10 5 managing with dataflow programming model 5 21 reading from and writing to with variant data 5 17 menu bar hiding 4 16 Menu Editor 15 2 menus 3 3 editing 15 2 handling selections 15 3 hot See the LabVIEW Help reference See the LabVIEW Help ring controls 4 13 shortcut 3 3 editing for polymorphic VIs See the LabVIEW Help meters See also numerics adding color ramps 4 9 front panel 4 8 methods ActiveX 18 1 moving arrays See the LabVIEW Help clusters See the LabVIEW Help objects See t
43. browser Configure the Web Server by selecting Tools Options and selecting the Web Server pages from the top pull down menu Use these pages to control browser access to the server and to specify which front panels are visible remotely You also can use these pages to set a time limit on how long any particular remote client can control a VI The Web Server allows multiple clients to connect simultaneously to the same front panel but only one client at a time can control the front panel The user at the server computer can regain control of any VI at any time When the controller changes a value on the front panel all client front panels reflect that change However client front panels do not reflect all changes In general client front panels do not reflect changes made to the display on front panel objects but rather to the actual values in the front panel objects For example if the controller changes the mapping mode or marker spacing of a scale of a chart or if the controller shows and hides a scrollbar for a chart only the controller front panel reflects these changes Remote Panel License You must configure a license to support the number of clients that potentially could connect to your server By default the remote front panel license included with LabVIEW allows one client to view and control a front panel When you exceed the number of clients allowed by your license the client receives a message that contains information you sp
44. can display in a multiplot graph If you want to access a single waveform from a file you must index the array of waveform data types as shown in Figure 13 5 Refer to the Arrays section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about indexing arrays The VI accesses a file that includes multiple waveforms The Index Array function reads the first and third waveforms in the file and plots them on two separate waveform graphs Refer to Chapter 8 Loop and Case Structures for more information about graphs National Instruments Corporation 13 11 LabVIEW User Manual Chapter 13 File 1 0 file path dialog if empty Read Waveform from File vi Prrrrxr2 Figure 13 5 Reading Multiple Waveforms from a File Flow Through Parameters Many File I O VIs and functions contain flow through parameters typically a refnum or path that return the same value as the corresponding input parameter Use these parameters to control the execution order of the functions By wiring the flow through output of the first node you want to execute to the corresponding input of the next node you want to execute you create artificial data dependency Without these flow through parameters you have to use Sequence structures to ensure that file I O operations take place in the order you want Refer to the Data Dependency and Artificial Data Dependency section of Chapter 5 Building the Block Diagram f
45. can slow performance LabVIEW User Manual 11 2 ni com Chapter 11 Graphs and Charts Customizing Graph and Chart Appearance You customize the appearance of graphs and charts by showing or hiding options Right click the graph or chart and select Visible Items from the shortcut menu to display or hide the following options Customizing Graphs Plot Legend Defines the color and style of the plot s Resize the legend to display multiple plots Scale Legend Defines labels for scales and configures scale properties Graph Palette Changes scaling and formatting while a VI is running X Scale and Y Scale Formats the x and y scales Refer to the Scale Options section of this chapter for more information about scales Cursor Legend graph only Displays a marker at a defined point coordinate You can display multiple cursors on a graph Scrollbar chart only Scrolls through the data in the chart Use the scroll bar to view data that the buffer does not currently display You can modify the behavior of graph cursors scaling options and graph axes Figure 11 1 illustrates the elements of a graph National Instruments Corporation 11 3 LabVIEW User Manual Chapter 11 Graphs and Charts p gt x scale name x scale name amp a Jeursor 0 fos Mes bell Be By cursor 1 23 04 aa elma 1 Plot legend 4 Mini grid mark 7 Cursor legend 10 Y scale 2 Cursor graph only 5 Graph pale
46. chart the graph or chart automatically plots a waveform based on the data start time and Ax of the waveform When you 11 16 ni com Chapter 11 Graphs and Charts wire an array of waveform data types to a waveform graph or chart the graph or chart automatically plots all the waveforms Refer to Chapter 5 Introduction to Data Acquisition in LabVIEW of the LabVIEW Measurements Manual for more information about using the waveform data type National Instruments Corporation 11 17 LabVIEW User Manual Graphics and Sound VIs Use the Graphics and Sound VIs and functions located on the Functions Graphics amp Sound palette to display or modify graphics and sound in VIs For more information Refer to the LabVIEW Help for more information about using graphics and sound in VIs Using the Picture Indicator The picture indicator located on the Controls Graph Ctls palette is a general purpose indicator for displaying pictures that can contain lines circles text and other types of graphic shapes Because you have pixel level control over the picture indicator you can create nearly any graphics object The picture indicator has a pixel based coordinate system in which the origin 0 0 is the pixel located at the top left corner of the control The horizontal x component of a coordinate increases toward the right and the vertical y coordinate increases toward the bottom If a picture is too large for the pi
47. click a button in the subsequent dialog box Refer to the Dialog Controls section of this chapter for more information about the dialog controls Selecting the Screen Size When you design a VI consider whether the front panel can display on computers with different screen resolutions Select File VI Properties select Window Size in the Category pull down menu and place a checkmark in the Maintain Proportions of Window for Different Monitor Resolutions checkbox to maintain front panel window proportions relative to the screen resolution National Instruments Corporation 4 19 LabVIEW User Manual Building the Block Diagram After you build the front panel you add code using graphical representations of functions to control the front panel objects The block diagram contains this graphical source code For more information Refer to the LabVIEW Help for more information about designing and configuring the block diagram Relationship between Front Panel Objects and Block Diagram Terminals Front panel objects appear as terminals on the block diagram Double click a block diagram terminal to highlight the corresponding control or indicator on the front panel Terminals are entry and exit ports that exchange information between the front panel and block diagram Data you enter into the front panel controls enter the block diagram through the control terminals When the VI finishes running the output data flow to t
48. cluster numeric types except that arrays of arrays are not allowed Arrays can be any size and can have any number of dimensions Clusters can have any number of elements The output type is of the same numeric representation as the input and the functions operate on each element of the cluster or array Refer to the Polymorphism for Numeric Functions section of this chapter for more information about two input polymorphic functions Allowable input type combinations for the two input Logarithmic functions include the following e Similar Both inputs have the same structure and the output has the same structure as the inputs e One scalar One input is a numeric scalar the other is a numeric array or cluster and the output is an array or cluster National Instruments Corporation B 7 LabVIEW User Manual Comparison Functions Use the Comparison functions located on the Functions Comparison palette to compare Boolean values strings numerics arrays and clusters Most Comparison functions test one input or compare two inputs and return a Boolean value For more information Refer to the LabV EW Help for more information about Comparison functions Comparing Boolean Values The Comparison functions treat the Boolean value TRUE as greater than the Boolean value FALSE Comparing Strings LabVIEW compares strings based on the numerical equivalent of the ASCII characters For example a with a decimal value
49. cluster to the selector terminal of a Case structure the case selector label displays two cases Error and No Error and the border of the Case structure changes color red for Error and green for No Error If an error occurs the Case structure executes the Error subdiagram Refer to the Case Structures section of Chapter 8 Loop and Case Structures for more information about using Case structures 6 10 ni com Creating Vis and SubVls After you learn how to build a front panel and block diagram you can create your own VIs and subVIs distribute VIs and build stand alone applications and shared libraries Refer to the LabVIEW Development Guidelines manual for more information about planning your project including information about common development pitfalls and tools you can use to develop your project For more information Refer to the LabVIEW Help for more information about creating and using subVIs saving VIs and building stand alone applications and shared libraries Planning and Designing Your Project Before you develop your own VIs create a list of tasks your users will need to perform Determine the user interface components and the number and type of controls and indicators you need for data analysis displaying analysis results and so on Think about and discuss with prospective users or other project team members how and when the user will need to access functions and features Create sample front pan
50. corresponding numeric data value right click the ring constant and select Visible Items Digital Display from the shortcut menu The VIs in Figures 18 1 and 18 2 both access the Microsoft Excel application and execute a method The Index parameter of the ActivateMicrosoftApp method has the following options MicrosoftWord MicrosoftPowerPoint MicrosoftMail MicrosoftAccess MicrosoftFoxPro MicrosoftProject and MicrosoftSchedulePlus To identify the numeric value of the Index parameter that corresponds to the MicrosoftAccess option in Figure 18 1 select the MicrosoftAccess option from the pull down menu in the ring constant The numeric value of the currently selected option appears in a box next to the ring constant Instead of using a ring constant you can enter the numeric value of an option into a numeric constant as shown in Figure 18 2 National Instruments Corporation 18 7 LabVIEW User Manual Calling Code from Text Based Programming Languages You can call most standard shared libraries in LabVIEW using the Call Library Function Node You also can call C code in LabVIEW using the Code Interface Node CIN Refer to the Using External Code in LabVIEW manual for more information about calling code from text based programming languages For more information Refer to the LabVIEW Help for more information about calling code from text based programming languages Call Library Function Node Use the Call
51. does not print the titlebar menu bar toolbar or scroll bars Select File VI Properties and select Print Options from the Category pull down menu for more control over how LabVIEW prints a VI when you select File Print Window or when you print programmatically Refer to the Printing Programmatically section of this chapter for more information about printing programmatically Printing Reports Use the Report Generation VIs located on the Functions Report Generation palette to print paper reports or to save HTML reports of the information the VI generates Create a basic report using the Easy Text Report VI or generate more complex reports using the other Report Generation VIs National Instruments Corporation 14 5 LabVIEW User Manual Chapter 14 Documenting and Printing Vis B Note HTML based report generation is available only in the LabVIEW Full and Professional Development Systems You can use the Report Generation VIs to perform the following tasks Set the report headers and footers Set text font size style and color Set margins and tabs Determine which information appears on which line or page of a report Set the report orientation portrait or landscape Include text from other files in a report Clear information from an existing report Automatically print a paper report or save an HTML report Append text graphics or tables to a report Dispose of a report after it prints Printing Programmatic
52. e Functions Built in execution elements comparable to an operator function or statement Refer to the Functions Overview section of this chapter for more information about the functions available in LabVIEW e SubVIs VIs used on the block diagram of another VI comparable to subroutines Refer to the SubVIs section of Chapter 7 Creating VIs and SubVIs for more information about using subVIs on the block diagram e Structures Process control elements such as Sequence structures Case structures For Loops or While Loops Refer to Chapter 8 Loop and Case Structures for more information about using structures e Formula Nodes Resizable structures for entering equations directly into a block diagram Refer to the Formula Nodes section of Chapter 20 Formulas and Equations for more information about using Formula Nodes e Property Nodes Sets or finds properties of a class Refer to the Property Nodes section of Chapter 16 Programmatically Controlling VIs for more information about using Property Nodes e Invoke Nodes Executes methods of a class Refer to the Invoke Nodes section of Chapter 16 Programmatically Controlling VIs for more information about using Invoke Nodes e Code Interface Nodes CINs Calls code from text based programming languages Refer to the Code Interface Node section of Chapter 19 Calling Code from Text Based Programming Languages for more information about calling code from text based progra
53. eee cseesecseceeceseceeeeseceeesaeesseeaeenseeasesenaes 11 8 Single Plot XY Graph Data Types eee eeceeseeseesecseceeesseeeeesseeseeeeesseeneens 11 9 Multiplot XY Graph Data Types uo eee eeseeseceeeeeeseeeseceeeeseseeeeseseeeeaee 11 10 Waveform Charts otc ccciurt itch EA E ated sad nad een kesh 11 10 Intensity Graphs and Charts eieren e ea EE E EE EE 11 11 Color Mapping e asa r E E ae E a E ei 11 12 Intensity Chart Options 222 teri aa a R EE E R seen ees 11 13 Intensity Graph Options cannone a e a ii i 11 13 Digitall Graphs renee u a e e a teres ee a a AA EEE 11 13 Masking Datena a a see ide 11 15 National Instruments Corporation xi LabVIEW User Manual Contents SD Graphs seieren ieee ei REEE dae ee tases ee Ma acts oan de lode ad a eave 11 15 Wavetorm Data Type sf scesseduscvessesiacess santhscdeusuetitensepsacdtes sabes vedasbesidsdhascsbaesedestapgeetsasiass 11 16 Chapter 12 Graphics and Sound VIs Using the Picture Indicator sonini aeae a E Ea e aa 12 1 Picture Plots V ISi ia e E T a A A eds Ns 12 3 Using the Polar Plot VI as a SubVLI seesseeseeesseeesseeeesrsresresesresrsresrsresesreresrs 12 3 Using the Waveform Plot VI as a SUDVI 0 eee eeceeeeceeceeeeeetseeneeeseeeeees 12 3 Using the Smith Plot VIs as SubVIs 00 ee eee ese eeeeeeeseeeseeseeeaeeeeeseeaeees 12 4 Picture Functions Vissi 25 0s jetliideva iia aden nine belive alae 12 5 Creating and Modifying Colors with the Picture Functions VIs 0
54. elements that carries the data start Brown time and At of a waveform Refer to the Waveform Data Type section of Chapter 11 Graphs and Charts for more information about the waveform data type Reference number refnum Aqua Variant Includes the control or indicator name the data Purple type information and the data itself Refer to the Handling Variant Data section of this chapter for more information about the variant data type He Ale Polymorphic Indicates that a VI or function accepts Purple more than one kind of data type Refer to the Polymorphic VIs and Functions section of this chapter for more information about polymorphism VIs and functions E Fl 1 0 1 0 I O name Passes DAQ channel names VISA resource Purple names and IVI logical names you configure to I O VIs to communicate with an instrument or a DAQ device Refer to the I O Name Controls and Indicators section of Chapter 4 Building the Front Panel for more information about the I O name data type ae Picture Displays pictures that can contain lines circles Blue text and other types of graphic shapes Refer to the Using the Picture Indicator section of Chapter 12 Graphics and Sound VIs for more information about the picture data type A j Many data types have a corresponding set of functions that can manipulate the data Refer to the Functions Overview section of this chapter for information about w
55. file with a VI When the VI runs it loads the menu from the rtm file You also can use the Menu Editor dialog box to build custom menus either with application items which are menu items LabVIEW provides in the default menu or with user items which are menu items you add LabVIEW defines the behavior of application items but you control the behavior of user items with the block diagram Refer to the Menu Selection Handling section of this chapter for more information about handling user menu item selections Use the Menu Editor dialog box to customize menus when editing a VI Use the Menu functions located on the Functions Application Control Menu palette to customize menus programmatically at run time The functions allow you to insert delete and modify the attributes of user 15 2 ni com Chapter 15 Customizing Vis items You can only add or delete application items because LabVIEW defines the behavior and state of application items Menu Selection Handling When you create a custom menu you assign each menu item a unique case insensitive string identifier called a tag When the user selects a menu item you retrieve its tag programmatically using the Get Menu Selection function Lab VIEW provides a handler on the block diagram for each menu item based on the tag value of each menu item The handler is a While Loop and Case structure combination that allows you to determine which if any menu is selected and to execute the appr
56. for another operation to complete configure the VI to run at time critical highest priority Refer to the Using LabVIEW to Create Multithreaded VIs for Maximum Performance and Reliability Application Note for more information about creating multithreaded VIs Refer to Chapter 15 Customizing VIs for more information about configuring how VIs run Correcting Broken VIs If a VI does not run it is a broken or nonexecutable VI The Run button often appears broken shown at left when you create or edit a VI If itis still broken when you finish wiring the block diagram the VI is broken and will not run Finding Causes for Broken VIs LabVIEW User Manual Click the broken Run button or select Window Show Error List to find out why a VI is broken The Error list window lists all the errors The VI List section lists the names of all VIs in memory that have errors The errors and warnings section lists the errors and warnings for the VI you select in the VI List section The Details section describes the errors and in some cases recommends how to correct the errors or how to find more information about them Select Help to open an online help file that lists LabVIEW errors and their descriptions Click the Show Error button or double click the error description to display the relevant block diagram or front panel and highlight the object that contains the error The toolbar includes the Warning button shown at left if a VI includes
57. for drawing pixmaps that are 2D arrays of 1 bit black and white 4 bit 8 bit and 24 bit data 12 6 ni com Chapter 12 Graphics and Sound VIs To manipulate the data as a 2D array you can convert it to the appropriate format using the Unflatten Pixmap VI and Flatten Pixmap VI located on the Functions Graphics amp Sound Graphics Formats palette Sound VIs Use the Sound VIs located on the Functions Graphics amp Sound Sound palette to integrate sound files and functions into your VIs You can use these VIs to perform the following tasks e Create VIs that play sound files such as a recorded warning when users perform certain actions e Create a VI that plays a sound file when the VI starts or finishes running or when you reach a certain point in the VI e Configure a sound input device to acquire sound data Use the Sound Input VIs to acquire the sound data You also can read any sound information coming through the device e Configure a sound output device to accept sound data from other Sound VIs You can control the volume of the sound going through the device play or pause the sound and clear the sound from your system National Instruments Corporation 12 7 LabVIEW User Manual File 1 0 File I O operations pass data to and from files Use the File I O VIs and functions located on the Functions File I O palette to handle all aspects of file I O including the following Opening and closing data files
58. formulas 20 1 functions 5 6 out of range 4 14 polymorphism B 2 strings and 9 5 units of measure 5 17 universal constants 5 4 writing data to spreadsheet or text files 9 5 objects ActiveX 18 1 aligning See the LabVIEW Help block diagram 5 1 captions on front panel 4 16 creating See the LabVIEW Help changing controls to and from indicators 4 2 coloring on front panel 4 4 copying colors See the LabVIEW Help configuring on front panel 4 1 controlling programmatically 16 8 creating descriptions 14 2 creating tip strips 14 2 displaying optional elements 4 2 finding See the LabVIEW Help l 19 See also the LabVIEW Help optional elements 4 2 inserting in palettes See the LabVIEW Help inserting on block diagram See the LabVIEW Help inserting on front panel using ActiveX 18 4 labeling 4 16 creating See the LabVIEW Help editing See the LabVIEW Help resizing See the LabVIEW Help moving See the LabVIEW Help overlapping on front panel 4 11 reordering See the LabVIEW Help replacing on block diagram See the LabVIEW Help replacing on front panel 4 2 resizing on front panel 4 5 in relation to window size 4 5 scaling on front panel 4 5 selecting See the LabVIEW Help setting navigation order on front panel 4 4 spacing evenly See the LabVIEW Help transparent See the LabVIEW Help wiring automatically on block diagram 5 11 wiring manually on block diagram 5 10 OLE for P
59. graphics You also can manually resize front panel objects and set them to automatically resize when the window size changes Refer to the LabVIEW Custom Controls Indicators and Type Definitions Application Note for more information about creating and using custom controls indicators and type definitions National Instruments Corporation 4 1 LabVIEW User Manual Chapter 4 Building the Front Panel Showing and Hiding Optional Elements Front panel controls and indicators have optional elements you can show or hide View a list of the available elements by right clicking an object and selecting Visible Items from the shortcut menu Most objects have a label and a caption Refer to the Labeling section of this chapter for more information about labels and captions Changing Controls to Indicators and Vice Versa LabVIEW initially configures objects in the Controls palette as controls or indicators based on their typical use For example if you select a toggle switch from the Controls Boolean palette it appears on the front panel as a control because a toggle switch is usually an input device If you select an LED it appears on the front panel as an indicator because an LED is usually an output device Some palettes contain a control and an indicator for the same type or class of object For example the Controls Numeric palette contains a digital control and a digital indicator You can change controls to indicators and vice versa
60. it from another application such as a word processing or spreadsheet application To store data in text format use the String functions located on the Functions String palette to convert all data to text strings Text files can contain information of different data types Text files typically take up more memory than binary and datalog files if the data is not originally in text form such as graph or chart data because the ASCII representation of data usually is larger than the data itself For example you can store the number 123 4567 in 4 bytes as a 13 2 ni com Chapter 13 File 1 0 single precision floating point number However its ASCII representation takes 9 bytes one for each character In addition it is difficult to randomly access numeric data in text files Although each character in a string takes up exactly byte of space the space required to express a number as text typically is not fixed To find the ninth number in a text file LabVIEW must first read and convert the preceding eight numbers You might lose precision if you store numeric data in text files Computers store numeric data as binary data and typically you write numeric data to a text file in decimal notation A loss of precision might occur when you read the data from the text file Loss of precision is not an issue with binary files Refer to the examples file smplfile 11b and examples file sprdsht 11b for examples of using file I O with text f
61. lose any detail Also it supports 1 bit 4 bit 8 bit and 24 bit graphics For lower bit depth the resulting graphic compresses much better than JPEG The PNG format replaces the Graphics Interchange Format GIF Although the PNG format has advantages over both JPEG and GIF it is not as well supported by most Web browsers The GIF format also compresses graphics well and is supported by most Web browsers Because of licensing issues LabVIEW does not save graphics as compressed GIF files but might in the future Use a graphics format converter to convert the uncompressed GIF files that LabVIEW saves to compressed GIF files You also can use a graphics format converter to convert the PNG graphics to GIF graphics Start out with PNG graphics because they are lossless reproductions of the original graphics Modify the HTML file to which you saved the VI documentation to refer to the GIF graphics with the gif extension Naming Conventions for Graphic Files When you save HTML files or RTF files with external graphics LabVIEW saves the control and indicator terminals to graphic files with consistent names If a VI has multiple terminals of the same type LabVIEW creates one graphic file that contains each terminal For example if a VI has three 32 bit signed integer inputs LabVIEW creates a single ci32 jpg file Creating Your Own Help Files You can use the HTML or RTF files LabVIEW generates to create your own compiled help files Windows
62. make a copy of a control or another object by clicking it while pressing the lt Ctrl gt key and dragging the copy to its new location Macintosh Press the lt Option gt key Sun Press the lt Meta gt key Linux Press the lt Alt gt key UNIX You also can clone an object by clicking the object with the middle mouse button and then dragging the copy to its new location A set of ordered unindexed data elements of any data type including numeric Boolean string array or cluster The elements must be all controls or all indicators CIN Special block diagram node through which you can link text based code to a VI LabVIEW User Manual Glossary coercion coercion dot Color Copying tool Coloring tool compile conditional terminal configuration utility connector connector pane constant Context Help window control control flow Controls palette conversion LabVIEW User Manual Automatic conversion LabVIEW performs to change the numeric representation of a data element Dot on a terminal that indicates that one of two terminals wired together LabVIEW has converted to match the data type of the other Copies colors for pasting with the Coloring tool Tool to set foreground and background colors Process that converts high level code to machine executable code LabVIEW compiles VIs automatically before they run for the first time after you create or edit alteration Terminal of a Whi
63. node completes execution it supplies data to its output terminals and passes the output data to the next node in the dataflow path Visual Basic C JAVA and most other text based programming languages follow a control flow model of program execution In control flow the sequential order of program elements determines the execution order of a program In LabVIEW because the flow of data rather than the sequential order of commands determines the execution order of block diagram elements you can create block diagrams that have simultaneous operations Lab VIEW is a multitasking and multithreaded system running multiple execution threads and multiple VIs simultaneously Refer to the Using LabVIEW to Create Multithreaded VIs for Maximum Performance and Reliability Application Note for more information about performing tasks simultaneously in Lab VIEW Data Dependency and Artificial Data Dependency LabVIEW User Manual The control flow model of execution is instruction driven Dataflow execution is data driven or data dependent A node that receives data from another node always executes after the other node completes execution Block diagram nodes not connected by wires can execute in any order Although the LabVIEW Development Guidelines manual recommends using a left to right and top to bottom layout nodes do not necessarily execute in left to right top to bottom order You can use a Sequence structure to control execution order
64. numeric representation to any other numeric representation When you wire two or more numeric inputs of different representations to a function the function usually returns output in the larger or wider format The functions coerce the smaller representations to the widest representation before execution and LabVIEW places a coercion dot on the terminal where the conversion takes place Some functions such as Divide Sine and Cosine always produce floating point output If you wire integers to their inputs these functions convert the integers to double precision floating point numbers before performing the calculation For floating point scalar quantities it is usually best to use double precision floating point numbers Single precision floating point numbers save little or no run time and overflow much more easily The analysis libraries for example use double precision floating point numbers You should only use extended precision floating point numbers when necessary The performance and precision of extended precision arithmetic varies among the platforms Refer to the Undefined or National Instruments Corporation B 1 LabVIEW User Manual Appendix B Polymorphic Functions Unexpected Data section of Chapter 6 Running and Debugging VIs for more information about floating point overflow For integers it is usually best to use a 32 bit signed integer If you wire an output to a destination that has a different numeric r
65. of 97 is greater than A 65 which is greater than the numeral o 48 which is greater than the space character 32 LabVIEW compares characters one by one from the beginning of the string until an inequality occurs at which time the comparison ends For example LabVIEW evaluates the strings abcd and abef until it finds c which is less than the value of e The presence of a character is greater than the absence of one Thus the string abcd is greater than abc because the first string is longer The functions that test the category of a string character such as the Decimal Digit and Printable functions evaluate only the first character of the string National Instruments Corporation C 1 LabVIEW User Manual Appendix C Comparison Functions Comparing Numerics The Comparison functions convert numeric values to the same representation before comparing them Comparisons with one or two inputs having the value Not a Number NaN return a value that indicates inequality Refer to the Undefined or Unexpected Data section of Chapter 6 Running and Debugging VIs for more information about the NaN value Comparing Arrays and Clusters Arrays LabVIEW User Manual Some Comparison functions have two modes for comparing arrays or clusters of data In Compare Aggregates mode if you compare two arrays or clusters the function returns a single scalar value In Compare Elements mode the function compares the elements individually
66. of the VI you are calling It does not create a permanent association to the VI or contain other VI information such as the name and location You can wire the Call By Reference Node inputs and outputs just like you wire any other VI Figure 16 5 shows how to use the Call By Reference Node to dynamically call the Frequency Response VI The Call By Reference Node requires the use of the Open VI Reference and the Close LV Object Reference functions similar to the functions you use for the Property Node and Invoke Node However the Call By Reference Node requires that you wire a strictly typed VI refnum to the type specifier VI Refnum input of the Open VI Reference function Wire a strictly typed VI refnum by selecting Controls Refnum VI Refnum and placing the refnum on the front panel Right click the refnum and select Select VI Server Class Browse from the shortcut menu The Choose the VI to open dialog box prompts you for a VI National Instruments Corporation 16 7 LabVIEW User Manual Chapter 16 Programmatically Controlling Vis ype specifier Vl Refnum for type only 4D Frequency Response vi Number of Steps 551 gt Low Frequency 051 Fgh Fieger Figure 16 5 Using the Call By Reference Node The VI you specify for strictly typed refnums provides only the connector pane information That is no permanent association is made between the refnum and the VI In particular avoid confusing selecting the VI co
67. on the front panel as shown in Figure 4 1 The regions define the positions of the other front panel objects in relation to the object you want to scale When you resize the front panel window the object you set to scale automatically resizes and repositions itself relative to its original location The gray lines disappear when you run the VI fpscalin vi Figure 4 1 Front Panel with Object Set to Scale When LabVIEW scales objects automatically it follows the same conventions as when you resize an object manually For example some objects can resize only horizontally or vertically and the font size remains the same when you resize an object After LabVIEW automatically scales an object the object might not scale back to its exact original size when you size the window back to its original position Before you save the VI select Edit Undo to restore the original front panel window and object sizes 4 6 ni com Chapter 4 Building the Front Panel You can set an array to scale or set the objects within an array to scale If you set the array to scale you adjust the number of rows and columns you can see within the array If you set the objects within the array to scale you always see the same number of rows and columns though different sizes within the array You also can set a cluster to scale or set the objects within the cluster to scale If you set the objects within the cluster to scale the cluster will adjust as wel
68. out of range below color index 0 and anything above 100 is mapped to the out of range above color index 255 11 12 ni com Chapter 11 Graphs and Charts B Note The colors you want the intensity graph or chart to display are limited to the exact colors and number of colors your video card can display You are also limited by the number of colors allocated for your display Intensity Chart Options The intensity chart shares many of the optional parts of the waveform charts which you can show or hide by right clicking the chart and selecting Visible Items from the shortcut menu In addition because the intensity chart includes color as a third dimension a scale similar to a color ramp control defines the range and mappings of values to colors Like waveform charts the intensity chart maintains a history of data or buffer from previous updates You can configure this buffer by right clicking the chart and selecting Chart History Length from the shortcut menu The default size for an intensity chart is 128 data points The intensity chart display can be memory intensive For example displaying a single precision chart with a history of 512 points and 128 y values requires 512 128 4 bytes size of a single precision number or 256 KB Intensity Graph Options The intensity graph works the same as the intensity chart except it does not retain previous data and does not include update modes Each time new data pass to an intens
69. plots you want to display until run time or you want to pass multiple points for multiple plots in a single update wire a 2D array of data to the chart As with the waveform graph by default waveform charts handle rows as new data for each plot Wire a 2D array data type to the chart right click the chart and select Transpose Array from the shortcut menu to treat columns in the array as new data for each plot 11 10 ni com Chapter 11 Graphs and Charts Intensity Graphs and Charts Use the intensity graph and chart to display 3D data on a 2D plot by placing blocks of color on a Cartesian plane For example you can use intensity graphs and charts to display patterned data such as temperature patterns and terrain where the magnitude represents altitude The intensity graph and chart accept a 2D array of numbers Each number in the array represents a specific color The indexes of the elements in the 2D array set the plot locations for the colors Figure 11 5 shows the concept of the intensity chart operation Input Array Color Map Definition Column y Array 0 1 2 Element Color o 50 50 13 5 blue Row x 1 45 61 10 6 purple 2 6 13 5 10 It red 13 dk red Resulting Plot 45 orange 3 50 yellow dk red It red blue 61 green 2 yellow green dk red 1 yellow orange purple 0 1 2 3 Figure 11 5 Intensity Chart Color Map The rows of the data pa
70. programmatic changes to the front panel made before the client connects to the front panel are not reflected on the client computer For example if a property node changes a caption on a control before a client connects to that front panel the client will see the original caption of the control not the changed caption Block diagrams that achieve certain user interface effects by polling properties of a front panel control might experience decreases in performance when you control the VI from a remote computer You can improve the performance of these VIs by using the Wait for Front Panel Activity function Low Level Communications Applications TCP and UDP LabVIEW User Manual LabVIEW supports several low level protocols you can use to communicate between computers Each protocol is different especially in the way it refers to the network location of a remote application Each protocol generally is incompatible with other protocols For example if you want to communicate between Macintosh and Windows you must use a protocol that works on both platforms such as TCP Transmission Control Protocol TCP and User Datagram Protocol UDP are available on all platforms LabVIEW supports TCP is a reliable connection based protocol It provides error detection and ensures that data arrive in order and without duplication For these reasons TCP is usually the best choice for network applications Although UDP can give higher perform
71. reading and displays the temperature and the timestamp on the front panel dstp localhost temp Figure 17 4 Converting Live Variant Data to Temperature Data LabVIEW User Manual 17 8 ni com Chapter 17 Networking in LabVIEW Publishing Vis on the Web 3 Use the LabVIEW Web Server to create HTML documents publish front panel images on the Web and embed VIs in a Web page You can control browser access to the published front panels and configure which VIs are visible on the Web Note Use the LabVIEW Enterprise Connectivity Toolset to control VIs on the Web and to add more security features to VIs you publish on the Web Refer to the National Instruments Web site at ni com for more information about this toolset Web Server Options Select Tools Options and select one of the Web Server items in the top pull down menu to set the following options e Set up the root directory and log file e Enable the Web Server e Control browser access to VI front panels e Configure which VI front panels are visible on the Web You must enable the Web Server in the Web Server Configuration page of the Options dialog box before you can publish VIs on the Web You also can enable the Web Server with the Web Publishing Tool described in the following section The VIs must be in memory before you publish them Creating HTML Documents Select Tools Web Publishing Tool to use the Web Publishing Tool to accomplish the following tas
72. result of the comparison e LabVIEW compares corresponding elements in each input array starting at the beginning of the array e If the corresponding elements are not equal LabVIEW stops the result of this comparison is used as the output of the comparison function e Ifthe corresponding elements are equal LabVIEW processes the next pair of values until it finds an inequality or reaches the end of one of the input arrays e Ifall values in the input arrays are equal but one array has extra elements at the end the longer array is considered greater than the shorter one For example LabVIEW considers the array 1 2 3 2 to be greater than the array 1 2 3 Clusters Clusters you want to compare must include the same number of elements each element in the clusters must be of compatible types and the elements must be in the same cluster order For example a cluster of a DBL and a string can be compared to a cluster of an 32 and a string Compare Elements Mode In Compare Elements mode Comparison functions output a cluster of Boolean elements one for each corresponding element in the input clusters Compare Aggregates Mode In Compare Aggregates mode Comparison functions output a single Boolean result LabVIEW compares corresponding elements until an inequality is found which determines the result The function considers the two clusters equal only if all elements are equal Use Compare Aggregates mode on clusters if
73. shown in the following plot A mask is a 2D array Each row in the array represents a plot on the digital graph To display Bits 1 and 5 on the plot enter 1 in one element of the array and 5 in another element as shown in Figure D 2 Enter 1 in the other elements of the array that should not plot a bit Figure D 2 Example of a Mask Array Control In this example each element in the array is identified by power of two 2 through 2 Use these numbers to identify which element in the array plots a bit to the graph In this example element 1 plots Bit 1 to the graph so any value of 1 in the bit assigns a 1 in the plot and any value of 0 assigns a 0 to the plot Element 2 plots Bit 5 to the graph so any value of 1 in the bit assigns a 2 to the plot and any value of 0 assigns a 0 to the plot The array in Figure D 2 results in the following plot on the digital waveform graph D 2 ni com Appendix D Masking Digital Data This plot indicates the following e Bit 1 and Bit 5 in the first element include a value of 0 e Bit 1 includes a value of 1 in both the second and third elements Bit 5 includes a value of 0 in both the second and third elements e Bit 1 in the fourth element includes a value of 0 Bit 5 in the fourth element includes a value of 1 e Bit 1 and Bit 5 in the fifth element include a value of 1 e Bit 1 in the sixth element includes a value of 1 Bit 5 in the sixth element includes
74. the entire slide and select Style Bold from the Text Settings pull down menu the scale digital display and label all change to a bold font If you select only the label and select Bold only the label changes to a bold font If you select text from a scale marker and select Bold all the markers change to a bold font Designing User Interfaces If a VI serves as a user interface or a dialog box front panel appearance and layout are important Design the front panel so users can easily identify what actions to perform You can design front panels that look similar to instruments or other devices Refer to the LabVIEW Development Guidelines manual for more information about designing user interfaces Refer to the Case and Sequence Structures section of Chapter 8 Loop and Case Structures for information about using events to enhance the functionality of user interfaces Using Front Panel Controls and Indicators LabVIEW User Manual Controls and indicators are the main components of the front panel When you design the front panel consider how users interact with the VI and group controls and indicators logically If several controls are related add a decorative border around them or put them in a cluster Use the decorations located on the Controls Decorations and Controls Classic Controls Decorations palettes to group or separate objects on a front panel with boxes lines or arrows These objects are for decoration only and d
75. the first few characters and LabVIEW finds a matching item in the listbox Press the lt Tab gt key to move to the next matching item Press the lt Shift Tab gt keys to move to the previous matching item Listboxes automatically have scroll bars but the scroll bars are activated only when the listbox includes more information than it can display 4 12 ni com Chapter 4 Building the Front Panel Ring and Enumerated Type Controls and Indicators Use the ring and enumerated type controls and indicators located on the Controls Ring amp Enum and Controls Classic Controls Ring amp Enum palettes to create a list of strings you can cycle through Ring Controls Ring controls are numeric objects that associate numeric values with strings or pictures Ring controls appear as pull down menus that users can cycle through to make selections Ring controls are useful for selecting mutually exclusive items such as trigger modes For example use a ring control for users to select from continuous single and external triggering The order of the items in the ring control is based on the order you enter the items Each item has a numeric value that ranges from 0 to n 1 where n is the number of items The ring control displays the last item if the user enters any value greater than or equal to n 1 and the first item if the user enters any value less than or equal to zero Ring controls support type completion and the pull down menus o
76. the next breakpoint or until the VI finishes running LabVIEW saves breakpoints with a VI but they are active only when you run the VI Suspending Execution Suspend execution of a subVI to edit values of controls and indicators to control the number of times it runs before returning to the caller or to go back to the beginning of the execution of the subVI You can cause all calls to a subVI to start with execution suspended or you can suspend a specific call to a subVI To suspend all calls to a subVI open the subVI and select Operate Suspend when Called The subVI automatically suspends when another VI calls it If you select this menu item when single stepping the subVI does not suspend immediately The subVI suspends when it is called To suspend a specific subVI call right click the subVI node on the block diagram and select SubVI Node Setup from the shortcut menu Place a checkmark in the Suspend when called checkbox to suspend execution only at that instance of the subVI National Instruments Corporation 6 5 LabVIEW User Manual Chapter 6 Running and Debugging VIs The Hierarchy Window which you display by selecting Browse Show VI Hierarchy indicates whether a VI is paused or suspended An arrow glyph indicates a VI that is running regularly or single stepping A pause glyph indicates a paused or suspended VI A green pause glyph or a hollow glyph in black and white indicates a VI that pauses when called A red
77. these VIs and functions to configure multiple VIs at the same time Also if you are on a network with other LabVIEW users you can use these VIs and functions to access and control VIs remotely Refer to Chapter 16 Programmatically Controlling VIs for more information about controlling VIs remotely Building Vis That Communicate with Other Applications Use the File I O VIs and functions located on the Functions File I O palette to write data to or read data from other applications such as Microsoft Excel You can use these VIs and functions to generate reports or incorporate data from another application in the VI Refer to Chapter 13 File I O for more information about passing data to and from other applications Use the Communication VIs and functions located on the Functions Communication palette to transfer Lab VIEW data across the Web using a communication protocol such as FTP and to build client server applications using communication protocols Refer to Chapter 17 Networking in LabVIEW for more information about communicating with other applications on the network or on the Web Windows Use the ActiveX functions located on the Functions Communication ActiveX palette to add ActiveX objects to VIs or to control ActiveX enabled applications Refer to Chapter 18 ActiveX for more information about using ActiveX technology National Instruments Corporation 7 3 LabVIEW User Manual Chapter 7 Creating Vis and SubVIs Su
78. to import code written in text based programming languages The manual includes information about shared external subroutines libraries of functions memory and file manipulation routines and diagnostic routines The manual also includes information about calling DLLs ay Note The Using External Code in LabVIEW manual is available only as a PDF e LabVIEW Application Notes Use the LabVIEW Application Notes to learn about advanced or specialized LabVIEW concepts and applications Refer to the NI Developer Zone at ni com for new and updated Application Notes e LabVIEW VXI VI Reference Manual Use this manual to learn about the VXI VIs for LabVIEW This manual is a companion guide to the NI VXI Programmer Reference Manual that comes with the VXI hardware 3 Note The LabVIEW VXI VI Reference Manual is available only as a PDF LabVIEW Example Vis and Tools Use the LabVIEW example VIs and tools to help you design and build VIs LabVIEW Example Vis LabVIEW includes hundreds of example VIs you can use and incorporate into your own VIs You can modify an example to fit your application or you can copy and paste from one or more examples into your own VI Browse or search the example VIs by selecting Help Find Examples Refer to the NI Developer Zone at ni com for additional example VIs LabVIEW Tools LabVIEW includes many tools to help you quickly configure your measurement devices including the following You can access the
79. unsigned 16 bit integer that represents milliseconds elapsed since the LabVIEW reference time which is midnight January 1 1904 13 18 ni com Chapter 13 File 1 0 You access the records of front panel datalog files with the same File I O functions you use to access datalog files you created programmatically Enter the datalog record type as the type input to the File Open function as shown in Figure 13 10 Figure 13 10 Retrieving Logged Data Using the File Open Function National Instruments Corporation 13 19 LabVIEW User Manual Documenting and Printing Vis You can use LabVIEW to document and print VIs The Documenting VIs section of this chapter describes how to record information about the block diagram and or the front panel at any stage of development in printed documentation about VIs The Printing VIs section of this chapter describes options for printing VIs Some options are more appropriate for printing information about VIs and others are more appropriate for reporting the data and results the VIs generate Several factors affect which printing method you use including if you want to print manually or programmatically how many options you need for the report format if you need the functionality in the stand alone applications you build and on which platforms you run the VIs The Printing Reports section of this chapter describes how to print reports in LabVIEW For more information
80. value For example you can use color boxes to indicate different conditions such as out of range values The color value is expressed as a hexadecimal number with the form RRGGBB The first two digits control the red color value The second two digits control the green color value The last two digits control the blue color value Set the color of the color box by clicking it with the Operating or Coloring tool to display the color picker Color Ramps A color ramp uses color to display its numeric value You configure a color scale that consists of at least two arbitrary markers each with a numeric value and a corresponding display color As the input value changes the color displayed changes to the color that corresponds to that value Color ramps are useful for visually indicating data ranges such as a warning range for when a gauge reaches dangerous values For example you can use a color ramp to set the color scale for intensity charts and graphs Refer to the Intensity Graphs and Charts section of Chapter 11 Graphs and Charts for more information about intensity charts and graphs Right click the color ramp and use the shortcut menu options to customize the appearance size colors and number of colors You also can add a color ramp to any knob dial or gauge on the front panel Meters have a visible color ramp by default National Instruments Corporation 4 9 LabVIEW User Manual Chapter 4 Building the Front Panel Butt
81. when natural data dependency does not exist Refer to the Sequence Structures section of Chapter 8 Loop and Case Structures for more information about Sequence structures You also can use flow through parameters to control execution order Refer to the Flow Through Parameters section of Chapter 13 File I O for more information about flow through parameters You also can create an artificial data dependency in which the receiving node does not actually use the data received Instead the receiving node uses the arrival of data to trigger its execution Refer to the Timing Template data dep VI in the examples general structs 11b for an example of using artificial data dependency 5 20 ni com Chapter 5 Building the Block Diagram Missing Data Dependencies Do not assume left to right or top to bottom execution when no data dependency exists Make sure you explicitly define the sequence of events when necessary by wiring the dataflow In the following example no dependency exists between the Read File function and the Close File function because the Read File function is not wired to the Close File function This example might not work as expected because there is no way to determine which function runs first If the Close File function runs first the Read File function does not work Read File Close File The following block diagram establishes a dependency by wiring an output of the Read File function to the Clos
82. wiring directly to the corresponding terminal on the subVI as shown in Figure 13 9 Figure 13 9 Retrieving Logged Data through SubVI Terminals If you run the VI the subVI does not run Instead it returns the logged data from its front panel to the VI front panel as a cluster Specifying Records The subVI has n logged records and you can wire any number from n to n 1 to the record terminal of the subVI You can access records relative to the first logged record using non negative record numbers 0 represents the first record 1 represents the second record and so on through n 1 which represents the last record You can access records relative to the last logged record using negative record numbers 1 represents the last record 2 represents the second to the last and so on through n which represents the first record If you wire a number outside the range n to n 1 to the record terminal the invalid record output is TRUE and the subVI retrieves no data Retrieving Front Panel Data Using File 1 0 Functions You also can retrieve data you logged from the front panel by using File I O VIs and functions such as the Read File function The data type of each record in the front panel datalog file creates two clusters One cluster contains a timestamp and the other cluster contains the front panel data The timestamp cluster includes an unsigned 32 bit integer that represents seconds and an
83. you are comparing two records containing sorted data where elements later in the cluster are considered secondary keys to elements earlier in the cluster For example a cluster containing two strings last name followed by first name would compare the first name fields only if the last name fields matched National Instruments Corporation C 3 LabVIEW User Manual Masking Digital Data On the block diagram create a mask by bundling the digital waveform with a 2D array of integers as shown in Figure D 1 Waveform Graph Masked Waveform Graph Figure D 1 Masking Digital Data Combine bits by specifying values in each row of the 2D Mask array For example consider a 1D array that consists of seven 8 bit numbers 1 2 7 32 55 82 and 127 The following table displays the binary representations of these numbers 1 2 7 32 55 82 127 Bit 0 1 0 1 0 1 0 1 Bit 1 0 1 1 0 1 1 1 Bit 2 0 0 1 0 1 0 1 Bit 3 0 0 0 0 0 0 1 Bit 4 0 0 0 0 1 1 1 Bit 5 0 0 0 1 1 0 1 Bit 6 0 0 0 0 0 1 1 Bit 7 0 0 0 0 0 0 0 National Instruments Corporation D 1 LabVIEW User Manual Appendix D LabVIEW User Manual Masking Digital Data Using a mask you can plot one bit on a graph and overlay another bit on the same plot For example Bit 1 includes the values 0 1 1 0 1 1 and 1 as shown in the following plot Bit 5 includes the values 0 0 0 1 1 0 and 1 as
84. 00 to the count terminal If one of the data sources includes only 50 elements the loop executes 50 times and indexes only the first 50 elements Use the Array Size function to determine the size of arrays 8 4 ni com Chapter 8 Loop and Case Structures When you auto index an array output tunnel the output array receives a new element from every iteration of the loop Therefore auto indexed output arrays are always equal in size to the number of iterations For example if the loop executes 10 times the output array has 10 elements If you disable auto indexing on an output tunnel only the element from the last iteration of the loop passes to the next node on the block diagram A bracketed glyph appears on the loop border to indicate that auto indexing is enabled The thickness of the wire between the output tunnel and the next node also indicates the loop is using auto indexing The wire is thicker when you use auto indexing because the wire contains an array instead of a scalar Auto Indexing with While Loops If you enable auto indexing for an array entering a While Loop the While Loop indexes the array the same way a For Loop does However the number of iterations a While Loop executes is not limited by the size of the array because the While Loop iterates until a specific condition is met When a While Loop indexes past the end of the input array the default value for the array element type passes into the loop You can prevent th
85. 12 6 Graphics Formats VIS siev ecsiiasGiiia tenis Se ha aint seen A E eet diads ae 12 6 SOUND VIS eces certs E NES A EE EEE E E E EE EEO E S 12 7 Chapter 13 File 1 0 Basics Ob FUTO inii Seve etdect tice deve sabe eal tec ates ine Bt A 13 1 Choosing a Bile VO FOr at ss ist ccceseesceoosssveh Laven sungesteescavsb ERT EEE EEE ERE E 13 2 When to Use Text Filessis ic csniinwe nats heniitin tenia ile teeta 2s 13 2 When to Use Binary Files ectc ces steer EEEE E EE nea E REREN 13 3 When to Use Datalog Files ici ee ec enee a e are E Taa anait as ie 13 4 Using Aigh Wevel Pile OVS ns 4 0cich a tess ieee ao eapis ee E rete 13 5 Using Low Level and Advanced File I O VIs and Functions eee eee eeeeees 13 6 Disk Shami Teke oa eaa eceuete E E E R E 13 7 Creating Text and Spreadsheet Files eee ceeeseesecseeeseeeseeseceeeeseeeeeaeseeeeseeseeeaees 13 8 Formatting and Writing Data to Files occ eeseeseeesecneeeseeseeeeeeseenees 13 8 Scanning Data from Files eee ennn a a i 13 9 Creating Binary Piles Asers a AE aE aE a e EE EEE A E E ETE AE r S 13 9 Creating Datalog File Seoci a a e a eat 13 10 Writing Waveforms t Piles oe decline eee es E E 13 10 Reading Waveforms from Files esrssioinneceo pininana e e i 13 11 Blow Through Parameters iena ei ui edee n pde aia e e eie 13 12 Creating Configuration Files insien a tlic ele tie 13 12 Using Configuration Settings Files 0 0 0 eee eseeseeeceeeeeeeeeeeeeeeeseeeaees 13 13 Windows Configu
86. 17 floating point numbers converting B 1 overflow and underflow 6 7 flow of execution 5 20 flow through parameters 13 12 fonts application 4 17 dialog 4 17 options 3 6 settings 4 17 system 4 17 For Loops 8 2 auto indexing to set count 8 4 controlling timing 8 6 count terminals 8 2 iteration terminals 8 2 shift registers 8 5 unexpected data 6 7 using See the LabVIEW Help foreground color of front panel objects See the LabVIEW Help format string parameter 9 4 LabVIEW User Manual Index formats for file I O 13 2 binary files 13 3 datalog files 13 4 text files 13 2 formatting graph scales 11 5 strings 9 4 specifiers 9 4 text on front panel 4 17 Formula Nodes 20 2 entering C like statements 20 2 entering equations 20 2 illustration 20 3 variables 20 3 formulas See equations free labels 4 16 creating See the LabVIEW Help frequently asked questions E 1 front panel 2 1 adding space without resizing 4 7 aligning objects See the LabVIEW Help captions 4 16 creating See the LabVIEW Help changing controls to and from indicators 4 2 clearing indicators See the LabVIEW Help coloring objects 4 4 background and foreground See the LabVIEW Help copying colors See the LabVIEW Help configuring objects 4 1 controlling objects programmatically 16 8 controlling objects remotely See the LabVIEW Help controlling remotely 17 10 controls 4 7 copying objects See the LabVIEW H
87. 4 8 string 4 10 display types 9 2 tables 9 2 tab 4 11 terminals table 5 2 type definitions 4 1 user interface design 4 18 conventions used in this manual xviii converting arrays to and from clusters See the LabVIEW Help directories to libraries See the LabVIEW Help LabVIEW data types to HTML 9 6 libraries to directories See the LabVIEW Help numerics to strings 9 5 XML to LabVIEW data 9 7 cooperation level setting See the LabVIEW Help ni com copying objects on front panel or block diagram See the LabVIEW Help VIs A 3 correcting VIs 6 2 debugging techniques 6 3 count terminals 8 2 auto indexing to set 8 4 creating arrays 9 11 binary files 13 9 charts See the LabVIEW Help control references See the LabVIEW Help datalog files 13 10 graphs See the LabVIEW Help icons 7 8 menus 15 2 object descriptions 14 2 palette views 3 5 revision history 14 2 spreadsheet files 13 8 subpalettes See the LabVIEW Help subVIs 7 8 situations to avoid See the LabVIEW Help text files 13 8 tip strips 14 2 user defined constants 5 4 VI descriptions 14 2 cursors adding to graphs See the LabVIEW Help graph 11 4 custom automation interfaces 18 6 customer education E 1 technical support E 1 customizing error codes See the LabVIEW Help front panel objects 4 1 National Instruments Corporation l 7 Index menus 15 2 palettes 3 4 VI appearance and behavior 15 1 work envi
88. 583 988 5 610 828 5 652 909 5 732 277 5 734 863 5 737 622 5 764 546 5 784 275 5 821 934 5 847 953 5 905 649 5 920 479 5 974 254 5 990 906 6 064 812 6 064 816 6 102 965 6 138 270 D384051 D387750 D384050 D384052 European Patent No s 0242131 Japanese Patent No s 3 016 783 Canadian Patent No s 1285655 Various other software products may be included with this version of LabVIEW If any software products listed below are included they are covered by various Patents as follows The LabVIEW Signal Processing Toolset is covered by one or more of the following Patents U S Patent No s 5 353 233 6 108 609 European Patent No s 0632899 Japanese Patent No s 2 697 957 The LabVIEW Datalogging and Supervisory Control Module is covered by one or more of the following Patents U S Patent No s 5 966 532 6 053 951 LabVIEW Real Time is covered by one or more of the following Patents U S Patent No s 6 173 438 The LabVIEW PID Control Toolset is covered by one or more of the following Patents U S Patent No s 6 081 751 The IVI Driver Toolset is covered by one or more of the following Patents U S Patent No s 5 963 726 6 085 156 The NI VISA software is covered by one or more of the following Patents U S Patent No s 5 724 272 5 710 727 5 847 955 5 640 572 5 771 388 5 627 988 5 717 614 The NI DAQ software is covered by one or more of the following Patents U S Patent No s 5 619 702 6 067 584 6 0
89. 96 094 6 052 743 6 148 438 5 926 775 5 987 530 6 073 205 The NI 488 or NI 488 2 NI GPIB software is covered by one or more of the following Patents U S Patent No s 5 974 541 5 964 892 5 958 028 5 987 530 6 073 205 The NI FBUS software including one or more of the NI FBUS Configurator software or the NI FBUS Monitor software is covered by one or more of the following Patents U S Patent No s 5 854 890 5 796 721 5 850 523 5 971 581 6 141 596 6 076 952 5 978 850 WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS 1 NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT INJURY TO A HUMAN 2 IN ANY APPLICATION INCLUDING THE ABOVE RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE IMPAIRED BY ADVERSE FACTORS INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY COMPUTER HARDWARE MALFUNCTIONS COMPUTER OPERATING SYSTEM SOFTWARE FITNESS FITNESS OF COMPILERS AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION INSTALLATION ERRORS SOFTWARE AND HARDWARE COMPATIBILITY PROBLEMS MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL DEVICES TRANSIENT FAILURES OF ELECTRONIC SYSTEMS HARDWARE AND OR SOFTWARE UNANTICIPATED USES OR MISUSES OR ERRORS ON THE PART
90. Help by selecting Help VI Function and How To Help The LabVIEW Help includes links to the following resources LabVIEW Tutorial LabVIEW Bookshelf which includes PDF versions of all the LabVIEW manuals and Application Notes Technical support resources on the National Instruments Web site such as the Developer Zone the KnowledgeBase and the Product Manuals Library Note Macintosh and UNIX National Instruments recommends that you use Netscape 6 0 or later to view the LabVIEW Help LabVIEW Measurements Manual Use this manual to learn more about building data acquisition and instrument control applications in LabVIEW If you are a new LabVIEW user read the Getting Started with LabVIEW manual and the LabVIEW User Manual before you read this manual LabVIEW Development Guidelines Use this manual to learn how to build VIs that are easy to understand use and revise The manual describes project tracking design and documentation techniques Note The printed LabVIEW Development Guidelines manual is available only in the LabVIEW Professional Development System The PDF is available in all packages of LabVIEW LabVIEW User Manual 1 2 ni com Chapter 1 Introduction to LabVIEW e Getting Started with Point By Point VIs Use this guide to learn about the point by point analysis VIs for LabVIEW e Using External Code in Lab VIEW Use this manual to learn how to use Code Interface Nodes and external subroutines
91. IEW applications on local and remote computers Windows If you want to access the features of many Microsoft applications such as embedding a waveform graph in an Excel spreadsheet use the ActiveX VIs and functions Refer to Chapter 18 ActiveX for more information about accessing ActiveX enabled applications and permitting other ActiveX applications access to LabVIEW National Instruments Corporation 17 1 LabVIEW User Manual Chapter 17 Networking in LabVIEW LabVIEW as a Network Client and Server You can use LabVIEW as a client to subscribe to data and use features in other applications or as a server to make LabVIEW features available to other applications Refer to Chapter 16 Programmatically Controlling VIs for more information about using the VI Server to control VIs on local and remote computers You control VIs by accessing properties and invoking methods using the Property Node and Invoke Node respectively Before you can access the properties and invoke methods of another application you must establish the network protocol you use to access the properties and methods Protocols you can use include HTTP and TCP IP The protocol you select depends on the application For example the HTTP protocol is ideal for publishing on the Web but you cannot use the HTTP protocol to build a VI that listens for data that another VI creates To do that use the TCP protocol Refer to the Low Level Communications Applications sec
92. Instruments Corporation 7 11 LabVIEW User Manual Chapter 7 Creating Vis and SubVIs Distributing Vis If you want to distribute VIs to other computers or to other users consider if you want to include block diagram source code users can edit or if you want to hide or remove the block diagram Select File Save With Options to save VIs without the block diagrams to reduce the file size and prevent users from changing the source code Saving a VI without the block diagram also prevents users from moving the VI to another platform or from upgrading the VI to a future version of LabVIEW UN Caution If you save VIs without block diagrams do not overwrite the original versions of the VIs Save the VIs in different directories or use different names Instead of removing the block diagram you can assign password protection to the block diagrams The block diagram is still available but users must enter a password to view or edit the block diagram Another option for distributing VIs is to create a stand alone application or shared library A stand alone application or shared library is appropriate when you do not expect your users to edit the VIs Users can run your application or use the shared library but they cannot edit or view the block diagrams Stand alone applications contain simplified menus Refer to the Porting and Localizing LabVIEW VIs Application Note for more information about porting VIs among platforms and localizing VIs B
93. Is as Individual Files cles eeeeseeeeeeeeees 7 10 Advantages of Saving VIs as Libraries 0 0 0 eee eeeeseeseceeceseeneeesesneeeneesees 7 10 Manaping VIs in LAbrariess sscces cesses cesscveeeupessesexevvectbbtvsuvevane E E 7 11 Namina VIS bess ass eisai eetieiteel ates aaee aveutve elas cn averse a 7 11 Saving for a Previous Version cece eeeseesceseeneeeseeseceeeesesseeesesseeeaeeseeeaeens 7 11 Distributing VInne a cantata eee ee AG teh Rn aaa 7 12 Building Stand Alone Applications and Shared Libraries 0 ec eeeeeeeeeeeeeeeeneeeees 7 12 Part Il Building and Editing Vis Chapter 8 Loop and Case Structures For Loop and While Loop Structures 2 0 0 0 cee eee seceeseceecesesseesseeseeesecaecneeeaeseeesaeenaes 8 2 FOr LOOPS eir ine ct ccety tous te seeatans E E A AE E A REE 8 2 While DOOPT a a E AOO O R NARE 8 2 Avoiding Infinite While Loops sssesssessseesseesssrsrereeresrsresrrsesresresesre 8 3 National Instruments Corporation ix LabVIEW User Manual Contents Auto Indexitig Loops sessirnir stbussessesuedssvuden teed swduasaesse s 8 4 Auto Indexing to Set the For Loop Count eee eeeeseeeeeeees 8 4 Auto Indexing with While Loops cee eeeeseesseeeeseeeeeeseeeseesees 8 5 Shift Registers mm LOOPS siiip i e i a i 8 5 Controlling Timms soise ii teehee nie E E E E ER EAEAN 8 6 Case and Sequence Structures eseeecesconcsccssnescceevsccenecsscessesasenseseceseessesseessesers 8 6 Case S MUuctures xis ses Lesion a NE EE ni
94. LabVIEW Help clusters See the LabVIEW Help front panel objects 4 5 in relation to window size 4 5 functions See the LabVIEW Help labels See the LabVIEW Help nodes See the LabVIEW Help tables See the LabVIEW Help user defined constants 5 5 LabVIEW User Manual 1 22 retrieving data programmatically 13 17 using file I O functions 13 18 using subVIs 13 17 reverting to last saved versions See the LabVIEW Help revision history creating 14 2 numbers 14 2 printing 14 3 revision number displaying in titlebar See the LabVIEW Help ring controls 4 13 using See the LabVIEW Help rotary controls and indicators 4 8 RTF saving to 14 3 rtm file 15 2 run mode opening VIs in See the LabVIEW Help running VIs 6 1 run time menu file 15 2 S saving files suggested location for A 3 saving VIs 7 10 for previous versions 7 11 individual files 7 10 libraries 7 10 reverting to last saved versions See the LabVIEW Help scaling front panel objects 4 5 graphs 11 5 schema for XML 9 7 scope chart 11 6 screen resolutions 4 19 ni com script nodes HiQ 20 5 MATLAB 20 5 scroll bars hiding 4 16 listboxes 4 12 ring controls 4 13 scrolling through a chart 11 3 searching for controls VIs and functions on the palettes 3 2 PDF versions of LabVIEW documentation 1 1 VI hierarchy See the LabVIEW Help selecting default instance of a polymorphic VI See the LabVIEW Help objects See the LabVIE
95. LabVIEW User Manual Chapter 11 Graphs and Charts Customizing Charts LabVIEW User Manual Unlike graphs which display an entire waveform that overwrites the data already stored charts update periodically and maintain a history of the data previously stored You can customize the waveform and intensity charts located on the Controls Graph palette to match your data display requirements or to display more information Options available for charts include a scroll bar a legend a palette a digital display and representation of scales with respect to time You can modify the behavior of chart history length update modes and plot displays Chart History Length LabVIEW stores data points already added to the chart in a buffer or the chart history The default size for a chart history buffer is 1 024 data points You can configure the history buffer by right clicking the chart and selecting Chart History Length from the shortcut menu You can view previously collected data using the chart scroll bar Right click the chart and select Visible Items Scrollbar from the shortcut menu to display a scroll bar Chart Update Modes Charts use three different modes to scroll data Right click the chart and select Advanced Update Mode from the shortcut menu Select Strip Chart Scope Chart or Sweep Chart The default mode is Strip Chart A strip chart shows running data continuously scrolling from left to right across the chart A scope char
96. NATIONAL INSTRUMENTS LabVIEW User Manual Wy NATIONAL November 2001 Edition gt INSTRUMENTS Part Number 320999D 01 Worldwide Technical Support and Product Information ni com National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin Texas 78759 3504 USA Tel 512 683 0100 Worldwide Offices Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 284 5011 Canada Calgary 403 274 9391 Canada Montreal 514 288 5722 Canada Ottawa 613 233 5949 Canada Qu bec 514 694 8521 Canada Toronto 905 785 0085 China Shanghai 021 6555 7838 China ShenZhen 0755 3904939 Czech Republic 02 2423 5774 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Greece 30 1 42 96 427 Hong Kong 2645 3186 India 91805275406 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Malaysia 603 9596711 Mexico 001 800 010 0793 Netherlands 0348 433466 New Zealand 09 914 0488 Norway 32 27 73 00 Poland 0 22 528 94 06 Portugal 351 1 726 9011 Russia 095 2387139 Singapore 2265886 Slovenia 386 3 425 4200 South Africa 11 805 8197 Spain 91 640 0085 Sweden 08 587 895 00 Switzerland 056 200 51 51 Taiwan 02 2528 7227 United Kingdom 01635 523545 For further support information see the Technical Support Resources appendix To comment on the documentation send e mail to techpubs ni com 1992 2001 National Instruments Corporation A
97. Node Expression Node HiQ Script node and MATLAB script node to perform mathematical operations on the block diagram Note You must have HiQ or MATLAB installed on your computer to use the script nodes because LabVIEW uses ActiveX technology to pass the script to HiQ or MATLAB for execution LabVIEW uses ActiveX technology which is available only on Windows to implement the script nodes Therefore script nodes are available only on Windows Because National Instruments ships HiQ with LabVIEW you can install the software at no extra cost to gain more functionality in handling equations National Instruments Corporation 20 1 LabVIEW User Manual Chapter 20 Formulas and Equations The script nodes are similar to the Formula Node but they allow you to import an existing HiQ or MATLAB script in ASCII form and run the script in LabVIEW As with a Formula Node you can pass data to and from the node Formula Nodes The Formula Node is a convenient text based node you can use to perform mathematical operations on the block diagram You do not have to access any external code or applications and you do not have to wire low level arithmetic functions to create equations In addition to text based equation expressions the Formula Node can accept text based versions of if statements while loops for loops and do loops which are familiar to C programmers These programming elements are similar to what you find in C programming but a
98. OF THE USER OR APPLICATIONS DESIGNER ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER COLLECTIVELY TERMED SYSTEM FAILURES ANY APPLICATION WHERE A SYSTEM FAILURE WOULD CREATE A RISK OF HARM TO PROPERTY OR PERSONS INCLUDING THE RISK OF BODILY INJURY AND DEATH SHOULD NOT BE RELIANT SOLELY UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE TO AVOID DAMAGE INJURY OR DEATH THE USER OR APPLICATION DESIGNER MUST TAKE REASONABLY PRUDENT STEPS TO PROTECT AGAINST SYSTEM FAILURES INCLUDING BUT NOT LIMITED TO BACK UP OR SHUT DOWN MECHANISMS BECAUSE EACH END USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE INCORPORATED IN A SYSTEM OR APPLICATION INCLUDING WITHOUT LIMITATION THE APPROPRIATE DESIGN PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION Contents About This Manual Organization of This Manual cece eee eeeceeeseeseeeaeeseeeaeenee CONVENTIONS aaien E E T Part LabVIEW Concepts Chapter 1 Introduction to LabVIEW LabVIEW Documentation ReSOUICES cccccccccesesseeeeeeeeseeeeeees LabVIEW Example VIs and Tools
99. Polymorphic Functions for more information about converting numeric values Before you convert data to integer data types use the Probe tool to check intermediate floating point values for validity Check for NaN by wiring the Comparison function Not A Number Path Refnum to the value you suspect is invalid Unexpected and Default Data in Loops For Loops produce unexpected values when the iteration count is zero for an auto indexed For Loop While Loops produce default data when the shift register is not initialized For Loops For Loops produce unexpected values if you wire 0 to the count terminal of the For Loop or if you wire an empty array to the For Loop as an input with auto indexing enabled The loop does not execute and only output tunnel with auto indexing disabled contains unexpected values Use shift registers to transfer values through a loop regardless of whether the loop executes National Instruments Corporation 6 7 LabVIEW User Manual Chapter 6 Running and Debugging VIs Refer to the For Loop and While Loop Structures section of Chapter 8 Loop and Case Structures for more information about For Loops auto indexing and shift registers While Loops If you do not initialize a shift register on a While Loop the output is the default value for the parameter 0 FALSE empty string and so on or the last value loaded into the shift register when you last ran the VI Default Data in Arrays Indexing beyond th
100. Reorder Controls In Cluster from the shortcut menu To wire clusters both clusters must have the same number of elements Corresponding elements determined by the cluster order must have compatible data types For example if a double precision floating point numeric in one cluster corresponds in cluster order to a string in the another cluster the wire on the block diagram appears broken and the VI does not run If numerics of different representations LabVIEW coerces them to the same representation Refer to the Numeric Conversion section of Appendix B Polymorphic Functions for more information about numeric conversion Use the Cluster functions located on the Functions Cluster palette to create and manipulate clusters such as the following tasks e Extract individual data elements from a cluster e Add individual data elements to a cluster e Break a cluster out into its individual data elements 9 14 ni com Local and Global Variables In LabVIEW you read data from or write data to a front panel object using its block diagram terminal However a front panel object has only one block diagram terminal and your application might need to access the data in that terminal from more than one location Local and global variables pass information between locations in your application that you cannot connect with a wire Use local variables to access front panel objects from more than one location in a single VI Use global vari
101. Schema eee eeceseeeeeeseseeeeseseeeeseeseeeaeeseees 9 7 Grouping Data with Arrays and Clusters 00 0 eecesecsseeseceeceseseeeesesseeeaeeseeeseeneees 9 8 ATEAYS 3 00 eai ale ease ek Aili a eet ee A 9 8 TN GX OS 522 iss pace ech tees ees nc ee eh Sessa seet EOR 9 8 Examples of Arrays 2 i0403 sees es ib nd ie Ga ea ans 9 8 Restrictions TOrArrays i csiscssestecevevecstepencuvestepdesdvetsvecsssvesteveeteevtent 9 11 Creating Array Controls Indicators and Constants eee 9 11 Array Index Displays cs cecrncacis wountpaeseeresoctesiev ses A R RE EER 9 11 Array FUNCtONS 4 34 aiid aedaes a a ine ied ea 9 12 Automatically Resizing Array Functions 9 12 CIUSUETS EEE eines eicosanoids eh avidity aut ets 9 13 LabVIEW User Manual X ni com Contents Chapter 10 Local and Global Variables Local Vartablesics tsice s sssctecapsesctuggadegdeseateenascststeneg O dees EE E S 10 1 Creating Local Variables pnsan sanies eae h tan an eels 10 2 Global Variablesic c ehn cele an ta bin AG le E A 10 2 Creating Global Variables ts u ss3 edctsevecdeetevsseeeds Rantecseetievivente Reveeenertedesspevees 10 2 Read and Write Variables ssc eae ait Aa ani wai Ae 10 3 Using Local and Global Variables Carefully ccc cies esceecseeeeeeeseeseesessesseeaeses 10 4 Initializing Local and Global Variables 2 0 0 0 eee ee eeeeeeseeeseeneeeseeseeneeaes 10 4 Race Conditions erar rerh e a ese E E E deel reese tases OTRE EEEE N e 10 4 Memory Consid
102. See the LabVIEW Help selecting 5 12 wiring automatically 5 11 guides See the LabVIEW Help manually 5 10 5 12 structures See the LabVIEW Help techniques 5 22 tool 5 12 units 5 18 wiring manually on block diagram 5 12 work environment options setting 3 6 See also the LabVIEW Help storing 3 6 working space adding to front panel or block diagram 4 7 worldwide technical support E 2 write globals 10 3 write locals 10 3 writing to files 13 1 National Instruments Corporation I 29 Index XML converting data types to 9 6 converting from 9 7 example 9 5 schema 9 7 x scales formatting 11 5 multiple 11 2 XY graphs 11 7 data types 11 9 11 10 Y y scales formatting 11 5 multiple 11 2 Z zooming on graphs and charts See the LabVIEW Help LabVIEW User Manual
103. Support for Custom ActiveX Automation Interfaces If you are writing an ActiveX client that accesses properties and methods from an ActiveX server using LabVIEW you can access custom interfaces exposed by the server The ActiveX server writer must make sure the parameters of the properties and methods in these custom interfaces have Automation IDispatch data types Refer to your server development programming environment documentation for more information about accessing custom interfaces Using Constants to Set Parameters in ActiveX Vis LabVIEW User Manual Some parameters in ActiveX nodes take a discrete list of valid values Select the descriptive name in the ring constant to set these parameter values To access the ring constant when building an ActiveX VI right click the parameter of the node that accepts data values and select Create Constant from the shortcut menu The selections available in the ring constant depend on the refnum passed to the node Figures 18 1 and 18 2 show examples of using ring and numeric constants to set parameter values 18 6 ni com Chapter 18 ActiveX Invoke Node Automation Close ni Application B ActivateMicrosoft4pp Bae b Index at _Application ActivateMicrosoft4pp Index Figure 18 2 Setting a Data Value with a Numeric Constant Parameters that accept data values have a small arrow to the left of the parameter name To view the
104. URL in the DataSocket Connection dialog box Refer to the Using DataSocket on the Front Panel section of this chapter for more information about using DataSocket technology on the front panel Refer to the Integrating the Internet into Your Measurement System white paper for more information about DataSocket technology This white paper is available as a PDF from the Installation CD in the manuals directory or from the National Instruments Web site at ni com URLs use communication protocols such as dstp ftp and file to transfer data The protocol you use in a URL depends on the type of data you want to publish and how you configure your network You can use the following protocols when you publish or subscribe to data using DataSocket e DataSocket Transport Protocol dstp The native protocol for DataSocket connections When you use this protocol the VI communicates with the DataSocket server You must provide a named tag for the data which is appended to the URL The DataSocket connection uses the named tag to address a particular data item on a DataSocket server To use this protocol you must run a DataSocket server e Windows OLE for Process Control opc Designed specifically for sharing real time production data such as data generated by industrial automation operations To use this protocol you must run an OPC server e Windows Logos An internal National Instruments technology for transmitting data between th
105. VIEW Help controlling behavior 7 3 copying A 3 creating 7 8 situations to avoid See the LabVIEW Help designing 7 8 determining current instance 6 6 displaying chain of callers 6 6 ni com displaying names when placed See the LabVIEW Help front panel 7 8 hierarchy 7 9 polymorphic VIs 5 13 printing VIs 14 7 remote front panels 17 13 removing from polymorphic VIs See the LabVIEW Help retrieving front panel data 13 17 suspending execution 6 5 support files for calling HiQ 20 7 technical E 1 suspending execution debugging VIs 6 5 sweep chart 11 6 switches on front panel 4 10 symbolic colors See system colors system colors 4 19 system colors See the LabVIEW Help System Exec VI 17 15 system font 4 17 system level commands 17 15 T tab controls 4 11 using See the LabVIEW Help tabbing through front panel objects 4 4 tables 9 2 using See the LabVIEW Help tanks See also numerics slide controls and indicators 4 8 TCP 17 14 VI Server 16 1 technical support resources E 1 telephone technical support E 2 National Instruments Corporation 1 25 Index terminals 2 3 adding to functions 5 9 block diagram 5 1 coercion dots 5 12 conditional 8 2 constants 5 4 control and indicator table 5 2 count 8 2 auto indexing to set 8 4 displaying 5 2 displaying tip strips See the LabVIEW Help finding See the LabVIEW Help front panel objects and 5 1 iteration For Loop
106. W Help tools manually See the LabVIEW Help wires 5 12 selector terminals 8 7 values 8 7 sequence local terminals 8 9 Sequence structures 8 8 accessing values with local and global variables 10 4 controlling execution order 5 20 overusing 8 10 using See the LabVIEW Help serpdrv file A 2 servers ActiveX 18 6 configuring for remote front panels 17 11 LabVIEW 17 12 Web browser 17 12 setting cooperation level See the LabVIEW Help work environment options 3 6 See also the LabVIEW Help National Instruments Corporation l 23 Index shared libraries building 7 12 distributing VIs 7 12 calling from LabVIEW 19 1 sharing files 7 2 live data programmatically 17 6 live data with other VIs and applications 17 2 palette views See the LabVIEW Help VIs 7 12 shift registers 8 5 default data 6 8 shortcut menus 3 3 in run mode 3 3 single stepping debugging VIs 6 4 sink terminals See indicators sizing See resizing slide controls and indicators 4 8 See also numerics sliders adding 4 8 smart buffers variant data 5 17 Smith plots 12 4 smooth updates during drawing See the LabVIEW Help for graphs 11 5 sound 12 7 source code control 7 2 source code See block diagram source terminals See controls spacing objects evenly See the LabVIEW Help speed of execution controlling 8 6 splitting strings See the LabVIEW Help LabVIEW User Manual Index spreadsheet files creating 13
107. a Currently you cannot create customized schemas and you cannot control how LabVIEW tags each piece of data Also you cannot convert entire VIs or functions to XML National Instruments Corporation 9 7 LabVIEW User Manual Chapter 9 Grouping Data Using Strings Arrays and Clusters Grouping Data with Arrays and Clusters Arrays LabVIEW User Manual Use the array and cluster controls and functions located on the Controls Array amp Cluster Functions Array and Functions Cluster palettes to group data Arrays group data elements of the same type Clusters group data elements of mixed types An array consists of elements and dimensions Elements are the data that make up the array A dimension is the length height or depth of an array An array can have one or more dimensions and as many as 23 1 elements per dimension memory permitting You can build arrays of numeric Boolean path string waveform and cluster data types Consider using arrays when you work with a collection of similar data and when you perform repetitive computations Arrays are ideal for storing data you collect from waveforms or data generated in loops where each iteration of a loop produces one element of the array You cannot create arrays of arrays However you can use a multidimensional array or create an array of clusters where each cluster contains one or more arrays Refer to the Restrictions for Arrays section of this chapter for mor
108. a warning and you placed a checkmark in the Show Warnings checkbox in the Error list window Configure LabVIEW to always show warnings in the Error list window by selecting Tools Options selecting Debugging from the top pull down menu and placing a checkmark in the Show warnings in error box by default checkbox You can make this change with the Error list window open and see the change immediately Warnings do not prevent you from running a VI They are designed to help you avoid potential problems in VIs 6 2 ni com Chapter 6 Running and Debugging Vis Common Causes of Broken Vis The following list contains common reasons why a VI is broken while you edit it The block diagram contains a broken wire because of a mismatch of data types or a loose unconnected end Refer to the Using Wires to Link Block Diagram Objects section of Chapter 5 Building the Block Diagram for more information about wiring block diagram objects A required block diagram terminal is unwired Select Help Show Context Help or refer to the LabVIEW Help to see which parameters a block diagram node requires A subVl is broken or you edited its connector pane after you placed its icon on the block diagram of the VI Refer to the SubVIs section of Chapter 7 Creating VIs and SubVIs for more information about subVIs Debugging Techniques If a VI is not broken but you get unexpected data you can use the following techniques to identify and correct p
109. a value of 0 e Bit 1 and Bit 5 in the seventh element include a value of 1 The numbers that appear in the plot are derived from the following equation bit value 1 or 0 x 2 another bit value 1 or 0 x 2 ement number J n bit value 1 or 0 x 2 701e nember point value of the plot In Figure D 3 the fourth 8 and sixth 32 elements plot Bits 5 and 1 respectively Figure D 3 Specifying the Same Bits in Different Elements The array in Figure D 3 results in the following plot Notice how the plots look similar but the numeric values differ National Instruments Corporation D 3 LabVIEW User Manual Appendix D Masking Digital Data Each row in the mask corresponds to a plot on the graph Add a new row to the mask to add a new plot on the digital graph as shown in the Figure D 4 o 01 e e s e S E Caes geo ge Be es ee ge I 1 i 1 i 2 3 4 5 6 y io Figure D 4 Creating Two Plots of Masked Data on a Digital Waveform Graph LabVIEW User Manual D 4 ni com Technical Support Resources Web Support National Instruments Web support is your first stop for help in solving installation configuration and application problems and questions Online problem solving and diagnostic resources include frequently asked questions knowledge bases product specific troubleshooting wizards manuals drivers software updates and more Web support is available throug
110. aN NI DAQ LabVIEW User Manual Object a chart or graph owns to displays the names and plot styles of plots on that chart or graph See VI library Box within a dialog box that lists all available choices for a command For example a list of filenames on a disk VI Library Variable that enables you to read or write to one of the controls or indicators on the front panel of a VI 2D array The standard National Instruments hardware configuration and diagnostic environment for Windows See buffer Horizontal bar that lists the names of the main menus of an application The menu bar appears below the titlebar of a window Each application has a menu bar that is distinct for that application although some menus and commands are common to many applications A procedure that is executed when an object receives a message A method is always associated with a class Application that runs several different threads of execution independently On a multiple processor computer the different threads might be running on different processors simultaneously Digital display value for a floating point representation of not a number Typically the result of an undefined operation such as log 1 Comprehensive driver software included with all National Instruments DAQ hardware G 10 ni com node numeric controls and indicators 0 object Object Shortcut Menu tool OLE one dimensional Operating tool P pal
111. abVIEW on anetwork you can define individual menus directories for each user which makes it easy to transfer views to other people When you create a new view of a palette LabVIEW uses a copy of the original default view upon which you can apply any changes LabVIEW copies the original built in palette located in the Labview menus directory before you make any changes The protection of the built in palettes ensures that you can experiment with the palettes without corrupting the original view How LabVIEW Stores Views The mnu files and 11b files contain one Controls palette and one Functions palette each In addition each file contains an icon for the Controls and Functions palettes You must store each subpalette you create in a separate mnu file When you select a view LabVIEW checks the menus directory for a directory that corresponds to that view It builds the top level Controls and Functions palettes and subpalettes from the root mnu file in that directory that LabVIEW automatically creates every time you create a view For each VI or control LabVIEW creates an icon on the palette For each subdirectory mnu file or 11b file LabVIEW creates a subpalette on the palette Building ActiveX Subpalettes If you use ActiveX controls on the front panel select Tools Advanced Import ActiveX Controls to convert a set of ActiveX controls to custom controls and add them to the Controls palette LabVIEW saves the controls in
112. abel Labeling tool LabVIEW LED National Instruments Corporation G 9 Glossary Hexadecimal Base 16 number system Window that graphically displays the hierarchy of VIs and subVIs Input Output The transfer of data to or from a computer system involving communications channels operator input devices and or data acquisition and control interfaces Graphical representation of a node on a block diagram Institute for Electrical and Electronic Engineers Front panel object that displays output such as a graph or LED Digital display value for a floating point representation of infinity VI that controls a programmable instrument Any of the natural numbers their negatives or zero Method of displaying three dimensions of data on a 2D plot with the use of color Internet protocol Terminal of a For Loop or While Loop that contains the current number of completed iterations Text object used to name or describe objects or regions on the front panel or block diagram Tool to create labels and enter text into text windows Laboratory Virtual Instrument Engineering Workbench LabVIEW is a graphical programming language that uses icons instead of lines of text to create programs Light emitting diode LabVIEW User Manual Glossary legend library listbox LLB local variable matrix Measurement amp Automation Explorer memory buffer menu bar method multithreaded application N
113. ables to access and pass data among several VIs For more information Refer to the LabVIEW Help for more information about using local and global variables Local Variables Use local variables to access front panel objects from more than one location in a single VI and pass data between block diagram structures that you cannot connect with a wire With a local variable you can write to or read from a control or indicator on the front panel Writing to a local variable is similar to passing data to any other terminal However with a local variable you can write to it even if itis acontrol or read from it even if it is an indicator In effect with a local variable you can access a front panel object as both an input and an output For example if the user interface requires users to log in you can clear the Login and Password prompts each time a new user logs in Use a local variable to read from the Login and Password string controls when a user logs in and to write empty strings to these controls when the user logs out National Instruments Corporation 10 1 LabVIEW User Manual Chapter 10 Local and Global Variables Creating Local Variables Right click an existing front panel object or block diagram terminal and select Create Local Variable from the shortcut menu to create a local variable A local variable icon for the object appears on the block diagram You also can select Functions Structures Local Variabl
114. abviewrc file in the program directory but the options file specified on the command line overrides conflicting entries in the program directory National Instruments Corporation 3 7 LabVIEW User Manual Building the Front Panel The front panel is the user interface of a VI Generally you design the front panel first then design the block diagram to perform tasks on the inputs and outputs you create on the front panel Refer to Chapter 5 Building the Block Diagram for more information about the block diagram You build the front panel with controls and indicators which are the interactive input and output terminals of the VI respectively Controls are knobs push buttons dials and other input devices Indicators are graphs LEDs and other displays Controls simulate instrument input devices and supply data to the block diagram of the VI Indicators simulate instrument output devices and display data the block diagram acquires or generates Select Window Show Controls Palette to display the Controls palette then select controls and indicators from the Controls palette and place them on the front panel For more information Refer to the LabVIEW Help for more information about designing and configuring the front panel Configuring Objects on the Front Panel You can customize the front panel by using the control and indicator shortcut menus by setting the order of front panel objects and by using imported
115. abviewrc file to store options that are different for each user such as font or color settings because entries in the labviewrc file in your home directory override conflicting entries in the program directory For example if you installed the LabVIEW files in opt labview LabVIEW first reads options from opt labview labviewrc If you change an option in the Options dialog box such as the application font LabVIEW writes that change to the labviewrc file The next time you start LabVIEW it uses the application font option in the labviewrc file instead of the default application font defined in opt labview labviewrc Option entries consist of an option name followed by a colon and a value The option name is the executable followed by a period and an option When LabVIEW searches for option names the search is case sensitive You can enclose the option value in double or single quotation marks For example to use a default precision of double add the following entry to the labviewrc file in your home directory labview defPrecision double If you want to use a different options file specify the file on the command line when you start LabVIEW For example to use a file named lvrc in the test directory instead of labviewrc type labview pref test lvrc LabVIEW writes all changes you make in the Options dialog box to the 1vrc options file When you specify an options file on the command line LabVIEW still reads the l
116. ace a script node on the block diagram and create a script using HiQ or MATLAB syntax LabVIEW communicates with the script server engine which is a program National Instruments Corporation 20 5 LabVIEW User Manual Chapter 20 Formulas and Equations that runs the script LabVIEW communicates and controls the script server engine using an industry established protocol Script server engines are installed with HiQ or MATLAB Because of the nature of the HiQ and MATLAB script languages the script node cannot determine the data type of terminals you created You must assign a LabVIEW data type to each script node terminal The script node in LabVIEW recognizes the data types HiQ or MATLAB support Table 20 1 shows LabVIEW data types and the corresponding data types in HiQ and MATLAB Table 20 1 LabVIEW HiQ and MATLAB Data Types LabVIEW HiQ MATLAB Data Type Data Type Data Type Integer Real Real Text Integer Vector Real Vector Real Vector Integer Matrix Real Matrix Real Matrix Complex Complex CDB Complex Vector Complex Vector BENE WENENENE EEE Complex Matrix Complex Matrix Programming Suggestions for HiQ and MATLAB Scripts The following programming techniques make it easier to debug a script e Write the script and run it in HiQ or MATLAB for testing and debugging purposes before you import it into LabVIEW e Right click the HiQ script n
117. ach activity examples Contains example VIs Select Help Find Examples to browse or search the examples manual1s Contains documentation in PDF format This folder does not contain the help files Access the PDFs by selecting Help Search the LabVIEW Bookshelf he1p Contains the help files Access the LabVIEW Help by selecting Help VI Function and How To Help serpdrv Support file for accessing the serial port on Windows and UNIX Distribute this file with any application that uses the serial port on these platforms In addition to the above directories Macintosh users have a shared libraries folder that contains support files for the LabVIEW application LabVIEW User Manual A 2 ni com Appendix A Organization of LabVIEW Suggested Location for Saving Files LabVIEW installs the vi 1ib and the resource directories for Lab VIEW system purposes only Do not save your files in these directories You can save your files in the following directories e user 1ib Any commonly used VIs that you want to appear on the Functions User Libraries palette Use for vi 1ib extensions i Note Save subVIs in the user lib directory only if they are portable without modification across projects Paths to VIs in user 11ib are absolute Paths to subVIs you save elsewhere are relative to the parent VI Therefore copying a VI from user 1ib to modify it for a special case does not change the path to its subVIs located in user
118. add new terminals A small direction arrow to the right of the property indicates a property you read A small direction arrow to the left of the property indicates a property you write Right click the property and select Change to Read or Change to Write from the shortcut menu to change the operation of the property The node executes from top to bottom The Property Node does not execute if an error occurs before it executes so always check for the possibility of errors If an error occurs in a property LabVIEW ignores the remaining properties and returns an error The error out cluster contains information about which property caused the error Implicitly Linked Property Nodes When you create a Property Node from a front panel object by right clicking the object and selecting Create Property Node from the shortcut menu LabVIEW creates a Property Node on the block diagram that is implicitly linked to the front panel object Because these Property Nodes are implicitly linked to the object from which it was created they have no refnum input and you do not need to wire the Property Node to the terminal of the front panel object or the control refnum Refer to the Controlling Front Panel Objects section of this chapter for more information about control refnums Invoke Nodes Use the Invoke Node to perform actions or methods on an application or a VI Unlike the Property Node a single Invoke Node executes only a single method on an appl
119. alettes c ccc eeeeeecescseesecsesseeeeseeseenees 3 5 Representing Toolsets in the Palettes 0 0 ccecsccecesseeeeeeeeeeeeeeee 3 6 Setting Work Environment Options eceeseesessecseeessessesseseensenees 3 6 How LabVIEW Stores Options 0 eee eeeeseeseceseeeeeeseeeeeeeeeseeeaees 3 6 WAndOWS vices Sass cates ese ietenses cs ant vae KES EEEa OE E aas 3 6 Macintosh isien aa a 3 6 UNIX ina iaaa aa tas AAE eens 3 7 Chapter 4 Building the Front Panel Configuring Objects on the Front Panel esseeseeeseesseersresrsresresrsrrsrssrsrerrsresresesrrsreeese 4 1 Showing and Hiding Optional Elements eee eeeeseeeeeeseceeeeeeeseeenees 4 2 Changing Controls to Indicators and Vice Versa cece ces eeeeseseeeeeeseeeeees 4 2 Replacing Front Panel Objects nrnna iaai i 4 2 Setting Keyboard Shortcuts for Controls ssssesessssesseeessesreresreressrsresesresreee 4 3 Controlling Button Behavior with Key Navigation 4 3 Setting the Navigation Order of Front Panel Objects 4 4 Coloring OBJECTS etos eina E E A E a A E Senate dee 4 4 Using Imported Graphics 000 ieee ea E E RO 4 4 Grouping and Locking Objects ee eceeeceseeseceseeseeeseseeesesseseaesseeeseesaees 4 5 Resizing Objects sse siesi caine wa neath ave an wie reseed 4 5 Scaling Front Panel OD ects asset hin Ate ihep heidi ie E eae 4 5 Adding Space to Front Panel without Resizing Window sssr 4 7 Front Panel Controls and Indicators o oo eee eee eceeeeeeeeseeeceesec
120. aling is enabled for graphs However autoscaling can slow performance Use the Operating or Labeling tool to change the horizontal or vertical scale directly Waveform Graph Scale Legend Use the scale legend to label scales and configure scale properties Use the Operating tool to click the Scale Format button shown at left to configure the format precision and mapping mode Use the Scale Lock button shown at left to toggle autoscaling for each scale the visibility of scales scale labels and plots and to format scale labels grids grid lines and grid colors Graph Scale Formatting You can format the scales of a graph to represent either absolute or relative time or amplitude Use absolute time format to display the time date or both for a scale If you do not want LabVIEW to assume a date use relative time format To select absolute or relative time format right click the graph select the scale you want to modify and select Formatting from the shortcut menu The Formatting dialog box appears where you specify different properties of the graph scale By default the x axis represents relative time and the y axis represents amplitude Using Smooth Updates Right click the graph and select Advanced Smooth Updates from the shortcut menu to use an offscreen buffer to minimize flashing Using Smooth Updates can slow performance depending on the computer and video system you use National Instruments Corporation 11 5
121. ally Use any of the following methods to print VIs programmatically rather than interactively with the Print dialog boxes that appear when you select File Print Window and File Print LabVIEW User Manual Set a VI to automatically print its front panel every time it finishes running Create a subVI to print the VI Use the VI Server to programmatically print any VI window or VI documentation at any time Refer to Chapter 16 Programmatically Controlling VIs for more information about using this method to print VIs Printing at Completion Select Operate Print at Completion to print a VI when it finishes running You also can select File VI Properties select Print Options from the Category pull down menu and place a checkmark in the Automatically Print Panel Every Time VI Completes Execution checkbox 14 6 ni com Chapter 14 Documenting and Printing Vis When you select this option LabVIEW prints the contents of the front panel every time the VI finishes running If you use the VI as a subVI LabVIEW prints when that subVI finishes running and before the subVI returns to the caller Using a SubVI to Selectively Print at Completion In some cases you might not want a VI to print every time it finishes running You might want printing to occur only if the user clicks a button or if some condition occurs such as a test failure You also might want more control over the format for the printout or you might want to print o
122. alone applications and shared libraries l 1 LabVIEW User Manual Introduction to LabVIEW LabVIEW is a graphical programming language that uses icons instead of lines of text to create applications In contrast to text based programming languages where instructions determine program execution LabVIEW uses dataflow programming where the flow of data determines execution In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then add code using graphical representations of functions to control the front panel objects The block diagram contains this code In some ways the block diagram resembles a flowchart You can purchase several add on software toolsets for developing specialized applications All the toolsets integrate seamlessly in LabVIEW Refer to the National Instruments Web site at ni com for more information about these toolsets LabVIEW Documentation Resources LabVIEW includes extensive documentation for new and experienced LabVIEW users All LabVIEW manuals and Application Notes are also available as PDFs You must have Adobe Acrobat Reader 4 0 or later installed to view the PDFs Refer to the Adobe Systems Incorporated Web site at www adobe com to download Acrobat Reader Refer to the National Instruments Product Manuals Library at ni com for updated documentation resources e LabVIEW Bookshelf Use this PDF to search PDF versions of
123. already in memory Naming VIs When you save VIs use descriptive names Descriptive names such as Temperature Monitor vi and Serial Write amp Read vi make it easy to identify a VI and know how you use it If you use ambiguous names such as VI 1 vi you might find it difficult to identify VIs especially if you have saved several VIs Consider whether your users will run the VIs on another platform Avoid using characters that some operating systems reserve for special purposes suchas lt gt and Macintosh Keep VI names less than 31 characters if your users might run them on MacOS 9 x or earlier Saving for a Previous Version You can save VIs for a previous version of LabVIEW to make upgrading LabVIEW convenient and to help you maintain the VIs in two versions of LabVIEW when necessary If you upgrade to a new version of LabVIEW you can go back to the last version of the VIs When you save a VI for the previous version LabVIEW converts not just that VI but all the VIs in its hierarchy excluding vi 1ib files Often a VI uses functionality not available in the previous version of LabVIEW In such cases LabVIEW saves as much of the VI as it can and produces a report of what it cannot convert The report appears immediately in the Warnings dialog box Click the OK button to acknowledge these warnings and close the dialog box Click the Save button to save the warnings to a text file to review later National
124. an example of a graph that accepts this data type A multiplot waveform graph accepts a cluster of an initial x value a Ax value and array that contains clusters Each cluster contains a point array that contains the y data You use the Bundle function to bundle the arrays into clusters and you use the Build Array function to build the resulting clusters into an array You also can use the Build Cluster Array which creates arrays of clusters that contain inputs you specify Refer to the Xo dX Y Multi Plot 2 graph in the Waveform Graph VI in the examples general graphs gengraph 11b for an example of a graph that accepts this data type A multiplot waveform graph accepts an array of clusters of an x value a Ax value and an array of y data This is the most general of the multiplot waveform graph data types because you can indicate a unique starting point and increment for the x axis of each plot Refer to the Xo dX Y Multi Plot 1 graph in the Waveform Graph VI in the examples general graphs gengraph 11b for an example of a graph that accepts this data type Single Plot XY Graph Data Types The single plot XY graph accepts a cluster that contains an x array and a y array The XY graph also accepts an array of points where a point is a cluster that contains an x value and a y value Refer to the XY Graph VI in the examples general graph gengraph 11b for an example of single plot XY graph data types National Instruments Corp
125. ance than TCP and does not require a connection it does not guarantee delivery Typically use UDP in applications in which guaranteed delivery is not critical For example an application might transmit data to a destination frequently enough that a few lost segments of data are not problematic Refer to the Using LabVIEW with TCP IP and UDP Application Note for more information about using TCP and UDP in LabVIEW applications 17 14 ni com DDE Windows Chapter 17 Networking in LabVIEW Dynamic Data Exchange DDE works at a higher level than TCP to exchange commands and data between clients and servers DDE is a good choice for communication with standard off the shelf applications such as Microsoft Excel Refer to the Using DDE in LabVIEW Application Note for more information about using DDE in LabVIEW applications Apple Events and PPC Toolbox Macintosh Pipe Vis UNIX The more common Macintosh only form of communication is Apple events As with DDE use Apple events to send messages to request actions or return information from other Macintosh applications Program to Program Communication PPC Toolbox is a lower level form of sending and receiving data between Macintosh applications PPC Toolbox gives higher performance than Apple events because the overhead required to transmit information is lower However because PPC Toolbox does not define the types of information you can transfer many applications do not support it PPC
126. ary when the temperature reaches 85 degrees Fahrenheit or higher emperature Histor E CWUIControlsLib CWwButton E Value OffText OffColor OnText OnColor In this case the CWButton acts as an LED changes colors and displays Warning when the temperature reaches the limit which is the on state of the CWButton object 3 Note In this example you could use the ActiveX Property Browser or property pages to set the OffText OffColor OnText and OnColor properties for the CWButton because you do not need to set those properties programmatically Refer to the ActiveX Property National Instruments Corporation 18 5 LabVIEW User Manual Chapter 18 ActiveX Browser and ActiveX Property Pages sections in this chapter for more information about the ActiveX Property Browser and property pages respectively LabVIEW as an ActiveX Server The LabVIEW application VIs and control properties and methods are available through ActiveX calls from other applications Other ActiveX enabled applications such as Microsoft Excel can request properties methods and individual VIs from LabVIEW and LabVIEW acts as an ActiveX server For example you can embed a VI graph in an Excel spreadsheet and from the spreadsheet enter data in the VI inputs and run the VI When you run the VI the data plot to the graph Refer to the examples comm fregresp x1s for an example of using LabVIEW properties and methods in an Excel spreadsheet
127. bVIEW performs a bit wise operation If the input is an integer the output has the same representation If the input is a floating point number LabVIEW rounds it to a long integer and the output is a long integer The logical functions work on arrays of numbers or Boolean values clusters of numbers or Boolean values arrays of clusters of numbers or Boolean values and so on A formal and recursive definition of the allowable input type is as follows Logical type Boolean scalar OR numeric scalar OR array logical type OR cluster logical types except that complex numbers and arrays of arrays are not allowed Logical functions with two inputs can have the same input combinations as the arithmetic functions However the logical functions have the further restriction that the base operations can only be between two Boolean values or two numbers For example you cannot have an AND between a Boolean value and a number The following example shows some combinations of Boolean values for the AND function LabVIEW User Manual B 4 ni com Appendix B Polymorphic Functions Similar One Scalar Boolean scalar ee Boolean scalar aeee A 27 Boolean scalar Boolean scalar ry ne oolean arra Boolean array A r Boolean array ae ED A Boolean arra Boolean array AD Boolean scalar Boolean cluster coo ee cluster cluster Array of array of clusters ae cluster array of clusters Polymorphism for A
128. bVls After you build a VI and create its icon and connector pane you can use it in another VI A VI called from the block diagram of another VI is called a subVI A subVI corresponds to a subroutine in text based programming languages A subVI node corresponds to a subroutine call in text based programming languages The node is not the subVI itself just as a subroutine call statement in a program is not the subroutine itself A block diagram that contains several identical subVI nodes calls the same subVI several times The subVI controls and indicators receive data from and return data to the block diagram of the calling VI Select VIs on the Functions Select a VI palette and place them on the block diagram to create a subVI call to that VI nye Note Before you can use a VI as a subVI you must set up a connector pane Refer to the Setting up the Connector Pane section of this chapter for more information about setting up a connector pane You can edit a subVI by using the Operating or Positioning tool to double click the subVI on the block diagram When you save the subVI the changes affect all calls to the subVI not just the current instance Watching for Common Operations As you create VIs you might find that you perform a certain operation frequently Consider using subVIs or loops to perform that operation repetitively For example the following block diagram contains two identical operations LabVIEW User Manual 7 4 n
129. because a slide does not have much in common with a string control You also can paste objects from the clipboard to replace existing front panel controls and indicators This method does not preserve any characteristics of the old object but the wires remain connected to the object Setting Keyboard Shortcuts for Controls You can assign keyboard shortcuts to controls so users can navigate the front panel without a mouse Right click the control and select Advanced Key Navigation from the shortcut menu to open the Key Navigation dialog box When a user enters the keyboard shortcut while running the VI the associated control receives the focus If the control is a text or digital control LabVIEW highlights the text so you can edit it If the control is Boolean press the spacebar or the lt Enter gt key to change its value The Advanced Key Navigation shortcut menu item is dimmed for indicators because you cannot enter data in an indicator Controlling Button Behavior with Key Navigation You can associate function keys with various buttons that control the behavior of a front panel You can define a button in a VI to behave like a dialog box so that pressing the lt Enter gt key becomes the same as clicking the default button Macintosh and Sun Pressing the lt Return gt key becomes the same as clicking the default button If you associate the lt Enter gt or the lt Return gt key with a dialog box button LabVIEW automati
130. bjects programmatically 16 8 front panel objects remotely See the LabVIEW Help instruments 7 2 source code 7 2 VIs programmatically 16 1 VIs remotely 17 10 VIs when called as subVIs 7 3 LabVIEW User Manual Index controls 4 1 2D 4 7 3D 4 7 ActiveX 18 2 adding to libraries 3 4 array 4 11 automation refnum 18 2 Boolean 4 10 using See the LabVIEW Help captions for subVI tip strips See the LabVIEW Help changing to indicators 4 2 classic 4 7 cluster 4 11 color box 4 9 color ramp 4 9 coloring 4 4 configuring 4 1 creating on block diagram See the LabVIEW Help data types table 5 2 dialog 4 15 using See the LabVIEW Help digital 4 9 displaying optional elements 4 2 enumerated type 4 13 advanced 4 13 using See the LabVIEW Help grouping and locking 4 5 guidelines for using on front panel 4 18 hidden See the LabVIEW Help hiding See also the LabVIEW Help optional elements 4 2 high color 4 7 T O name 4 14 keyboard shortcuts 4 3 listbox 4 12 using See the LabVIEW Help low color 4 7 LabVIEW User Manual l 6 naming 7 9 numeric 4 8 using See the LabVIEW Help optional 7 7 palette 3 1 customizing 3 4 navigating and searching 3 2 path 4 10 using See the LabVIEW Help printing 14 3 refnum 4 15 using See the LabVIEW Help replacing 4 2 required 7 7 resizing 4 5 in relation to window size 4 5 ring 4 13 using See the LabVIEW Help rotary 4 8 slide
131. by right clicking the object and selecting Change to Control or Change to Indicator from the shortcut menu Replacing Front Panel Objects LabVIEW User Manual You can replace a front panel object with a different control or indicator When you right click an object and select Replace from the shortcut menu a temporary Controls palette appears even if the Controls palette is already open Select a control or indicator from the temporary Controls palette to replace the current object on the front panel Selecting Replace from the shortcut menu preserves as much information as possible about the original object such as its name description default data dataflow direction control or indicator color size and so on However the new object retains its own data type Wires from the terminal of the object or local variables remain on the block diagram but they might be broken For example if you replace a numeric terminal with a string terminal the original wire remains on the block diagram but is broken The more the new object resembles the object you are replacing the more original characteristics you can preserve For example if you replace a slide with a different style slide the new slide has the same height scale value name description and so on If you replace the slide with a string 4 2 ni com Chapter 4 Building the Front Panel control instead Lab VIEW preserves only the name description and dataflow direction
132. c Files eee 14 4 Creating Your Own Help Files eee cseeseeeeceeeneeesesseeneeeeees 14 4 Printing VS segec2 edt eee AAA A eid ine e Gunde S 14 5 Printing the Act ve Window ahere ea eea e ea E 14 5 Printing Reports ern e a R a E A A E 14 5 Printing Programmatically nienia rra E E a 14 6 Printing at Completions esei a a e aas 14 6 Using a SubVI to Selectively Print at Completion 0 14 7 Additional Printing Techniques ceeeceesseeseceseesseceseeececeseceaeeeseeeeseeeeeeeeaee 14 7 Chapter 15 Customizing Vis Configuring the Appearance and Behavior Of VIs 0 eee eseeeeseeseeeeeeseeneeeseteeeeseenees 15 1 Customizing MENUS seeen A E ea Ania eae ea eee 15 2 Creating Menus erae Hives a EA E E E ANE 15 2 Menu Selection Handling eee ee ceceeseceeeeseceeeeseseeecsesesesseeeaeeseseaeeneenes 15 3 Chapter 16 Programmatically Controlling Vis Capabilities ofthe VL Servei ieoi iiaii E O EE E REE E E 16 1 Building VI Server Applications ssessesesssresesseresresesrestestsrestsentsrentesrerestesrsreneseentees 16 2 Application and VI References 0 ccccececeesesecsscseeeescsscsseseesscsseseesenseseneees 16 3 Manipulating Application and VI Settings oe eee eeeeeceeceseeeeesseeseesseeaseneeeaeeaes 16 3 Property Node Senioaren ee R E ER AE EE 16 3 Implicitly Linked Property Nodes sseesseesseessseesreeesersrrsrsrrerserer 16 4 INVOK ENG S NEEE ENA E ETE E EAEE E 16 4 Manipulating Application Class Properties a
133. cal including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation Portions 1991 1999 Compuware Corporation Uses libmng an open source initiative by Gerard Juyn 2000 2001 G Juyn www libmng com Based in part on the works of the Independant JPEG Group IJG 1991 1998 Thomas G Lane www ijg org Uses Icms little CMS by Marti Maria Saguer distributed under LGPL www 1littlecms com ses zlib a patent free de compression library 1995 1998 Jean loup Gailly and Mark Adler http www info zip org pub infozip zlib a Trademarks ComponentWorks DAQPad DataSocket HiQ HiQ Script LabVIEW National Instruments NI ni com NI 488 NI 488 2 NI DAQ NI FBUS NI VISA and SCXI are trademarks of National Instruments Corporation Product and company names mentioned herein are trademarks or trade names of their respective companies Patents The product described in this manual may be protected by one or more U S patents foreign patents or pending applications Refer to ni com legal patents for the most current list of patents covering this product The LabVIEW software is covered by one or more of the following Patents United States Patent No s 4 901 221 4 914 568 5 291 587 5 301 301 5 301 336 5 475 851 5 481 740 5 481 741 5 497 500 5 504 917 5
134. cally draws that button with a thick border around it If you associate the lt Enter gt or the lt Return gt key with a control no string control on that front panel can receive a carriage return Consequently all strings on that front panel are limited to a single line You can use scroll bars to navigate longer strings If you cycle to a Boolean control and press the lt Enter gt or the lt Return gt key the Boolean control changes even if another control uses the lt Enter gt or the lt Return gt key as its keyboard shortcut The assigned lt Enter gt or lt Return gt keyboard shortcut applies only when a Boolean control is not selected National Instruments Corporation 4 3 LabVIEW User Manual Chapter 4 Building the Front Panel Coloring Objects Setting the Navigation Order of Front Panel Objects You can set the navigation order of front panel objects by selecting Edit Set Tabbing Order You can then press the lt Tab gt key to navigate those objects while running the VI Controls and indicators on a front panel have an order called panel order that is unrelated to their position on the front panel The first control or indicator you create on the front panel is element 0 the second is 1 and so on If you delete a control or indicator the panel order adjusts automatically The panel order determines the navigation order while a VI is running The panel order also determines the order in which the controls and
135. cate ania aie a ee a eed Sates 5 5 FUNCUONS OVERVIEW csser e e AEE desis vevash a EE ETS ECEE 5 6 Numeric Functions senesnio ate dee Ain dees ade hats 5 6 BOGE an PUM CU OMS 3h se esdecd ste se saeh iat E E E sens kis apes debs 5 6 String PUN NOS fees Acticin EEE E N a 5 7 ATL AY BUNCTIOMS e AAE EEE E E ETE 5 7 Cl ster Function S 33230 na a na eara EEA a tara R 5 7 Comparison FPUNCHONS inis iae rn ea E r EE E a E N a 5 8 Time and Dialog Functions ceceseeeeeeeeeseeseeseeeseceeeeaecneeeseseeeaeesees 5 8 Ple Functions a serip cece seed cu vette scepter gdh evveutl te a e a cusepebedy 5 8 Waveform Functions inresa eane A EA RE ER R 5 8 Application Control Functions s sssessssssssesesesessesesssessseesesesenrssesesenesenesnssesene 5 9 Advanced Functions sina a a ONR e R n a at 5 9 Adding Terminals to Block Diagram Functions sssssssssesesesesssssseseseressssesese 5 9 National Instruments Corporation vii LabVIEW User Manual Contents Using Wires to Link Block Diagram Objects eee eceseeeeeseeeseeseseeeeaeteeeseeeeeeees 5 10 Automatically Wiring Objects oe eee ceeeseeseeeseeeeeeseeseessecsecesesseeneeeaeenees 5 11 Manually Wiring Objects oe ee cece eeceseceeceeeeeeeseceseeseeseeeaeeneeeaeseaeeaeenaes 5 12 Selecting WALES eoecsss cessasiecseicetyssnpeteades a E E echendaasouiaeces tases 5 12 Removing Broken Wifes sciis ieie ara ier eio ia aR 5 12 Coercion DOS i ia aeieea ear aesa Eoas S ED eari I osa R EESE aED 5 12 Polym
136. cause the VI to behave incorrectly If you do not initialize the variable before the VI reads the variable for the first time the variable contains the default value of the associated front panel object Because VIs follow a dataflow execution model LabVIEW local and global variables do not behave like local and global variables in text based programming languages A race condition occurs when two or more pieces of code that execute in parallel change the value of the same shared resource typically a local or global variable Figure 10 1 shows an example of a race condition 10 4 ni com Chapter 10 Local and Global Variables Figure 10 1 Race Condition The output of this VI depends on the order in which the operations run Because there is no data dependency between the two operations there is no way to determine which runs first To avoid race conditions do not write to the same variable you read from Refer to the Data Dependency and Artificial Data Dependency section of Chapter 5 Building the Block Diagram for more information about data dependency If you use global variables in VIs that execute in parallel you can use an additional Boolean global variable to indicate when global variable data changes Other VIs can monitor this Boolean global variable to determine if the data changed and to read the new value Memory Considerations when Using Local Variables When you create subVIs you create a connector pa
137. constants GPIB synonymous with HP IB The standard bus used for controlling electronic instruments with a computer Also called IEEE 488 bus because it is defined by ANSI TEEFE Standards 488 1978 488 1 1987 and 488 2 1992 Accesses and passes data among several VIs on a block diagram Small picture or icon See General Purpose Interface Bus 2D display of one or more plots A graph receives and plots data as a block Front panel object that displays data in a Cartesian plane Collection of input or output channels or ports that you define Groups can contain analog input analog output digital input digital output or counter timer channels A group can contain only one type of channel Use a task ID number to refer to a group after you create it You can define up to 16 groups at one time To erase a group pass an empty channel array and the group number to the group configuration VI You do not need to erase a group to change its membership If you reconfigure a group whose task is active LabVIEW clears the task and returns a warning LabVIEW does not restart the task after you reconfigure the group Pointer to a pointer to a block of memory that manages reference arrays and strings An array of strings is a handle to a block of memory that contains handles to strings G 8 ni com hex Hierarchy Window T O icon IEEE indicator Inf instrument driver integer intensity map plot IP iteration terminal l
138. contents of the file that a refnum is referencing without closing and reopening the file Because a refnum is a temporary pointer to an open object it is valid only for the period during which the object is open If you close the object LabVIEW disassociates the refnum with the object and the refnum becomes obsolete If you open the object again LabVIEW creates a new refnum that is different from the first refnum LabVIEW remembers information associated with each refnum such as the current location for reading from or writing to the object and the degree of user access so you can perform concurrent but independent operations on a single object If a VI opens an object multiple times each open operation returns a different refnum Dialog Controls Use the dialog controls located on the Controls Dialog Controls palette in dialog boxes you create The dialog controls and indicators are designed specifically for use in dialog boxes and include ring controls buttons tabbed dialog boxes checkboxes and radio buttons These controls differ from those that appear on the front panel only in terms of appearance These controls appear in the colors you have set up for your desktop National Instruments Corporation 4 15 LabVIEW User Manual Chapter 4 Building the Front Panel Labeling Because the dialog controls change appearance depending on which platform you run the VI the appearance of controls in VIs you create is compatible on a
139. cture indicator that displays it LabVIEW crops the picture so you can see only the pixels that fit within the display region of the indicator Use the Positioning tool to resize the indicator and run the VI again to view the entire picture To programmatically read or change the size of the picture area of the picture indicator use the Draw Area Size property To read the size of the entire picture indicator use the Bounds property You also can use the Positioning tool to select the indicator select Edit gt Customize Control and use the Control Parts window of the Control Editor to determine the size of the entire picture indicator and the size of the display region of the picture indicator National Instruments Corporation 12 1 LabVIEW User Manual Chapter 12 Graphics and Sound VIs LabVIEW User Manual When you place a picture indicator on the front panel it appears as a blank rectangular area and a corresponding terminal shown at left appears on the block diagram Use the Picture Functions VIs located on the Functions Graphics amp Sound Picture Functions palette instead of a graphics application to modify and add functionality to graphics in LabVIEW To display an image in a picture indicator you must use the Picture Functions VIs to specify a set of drawing instructions Each VI takes a set of inputs that describes a drawing instruction Based on these inputs the VI creates a compact description of these specifications
140. data in the following ways e Use the same VI from which you recorded the data to retrieve the data interactively e Use the VI as a subVI to retrieve the data programmatically e Use the File I O VIs and functions to retrieve the data Each VI maintains a log file binding that records the location of the datalog file where LabVIEW maintains the logged front panel data Log file binding is the association between a VI and the datalog file to which you log the VI data A datalog file contains records that include a timestamp and the data from each time you ran the VI When you access a datalog file you select which record you want by running the VI in retrieval mode and using the front panel controls to view the data When you run the VI in retrieval mode a numeric control appears at the top of the front panel so you can navigate among the records Refer to Figure 13 7 for an example of this numeric control Automatic and Interactive Front Panel Datalogging Select Operate Log at Completion to enable automatic logging The first time you log front panel data for a VI LabVIEW prompts you to name the datalog file LabVIEW logs data each time you run the VI and appends a new record to the datalog file each additional time you run the VI You cannot overwrite a record after LabVIEW writes it to a datalog file To log your data interactively select Operate Data Logging Log LabVIEW appends the data to the datalog file immediately Log y
141. deal in lengthy data acquisition operations where speed is critical You can write data continuously to a file while acquisition is still in progress For best results avoid running other VIs and functions such as Analyze VIs and functions until you complete the acquisition National Instruments Corporation 13 7 LabVIEW User Manual Chapter 13 File 1 0 Creating Text and Spreadsheet Files To write data to a text or spreadsheet file you must convert your data to a string To write data to a spreadsheet file you must format the string as a spreadsheet string which is a string that includes delimiters such as tabs Refer to the Formatting Strings section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about formatting strings Writing text to text files requires no formatting because most word processing applications that read text do not require formatted text To write a text string to a text file use the Write Characters To File VI which automatically opens and closes the file Use the Write To Spreadsheet File VI or the Array To Spreadsheet String function to convert a set of numbers from a graph a chart or an acquisition into a spreadsheet string Refer to the Using High Level File I O VIs and Using Low Level and Advanced File I O VIs and Functions sections of this chapter for more information about using these VIs and functions Reading text from a word processing application might re
142. der than indicator terminals Also a blank arrow appears on the right if the terminal is a control and an arrow appears on the left if the terminal is an indicator Table 5 1 Control and Indicator Terminals Control Indicator Data Type Color san Single precision floating point numeric Orange Double precision floating point numeric Orange bexT Extended precision floating point numeric Orange Pesa Complex single precision floating point numeric Orange Complex double precision floating point numeric Orange bexr Complex extended precision floating point numeric Orange Signed 8 bit integer numeric Blue Signed 16 bit integer numeric Blue Signed 32 bit integer numeric Blue Unsigned 8 bit integer numeric Blue Unsigned 16 bit integer numeric Blue Unsigned 32 bit integer numeric Blue Eo Enumerated type Blue Boolean Green String Pink LabVIEW User Manual 5 2 ni com Chapter 5 Building the Block Diagram Table 5 1 Control and Indicator Terminals Continued Control Indicator Data Type Color E l Array Encloses the data type of its elements in square Varies brackets and takes the color of that data type 208 Cluster Encloses several data types Cluster data types Brown or are brown if the elements of the cluster are the same type Pink or pink if the elements of the cluster are different types Path Aqua Waveform Cluster of
143. ding rectangle of a string The fourth row of the Picture Functions palette contains VIs you use to draw pixmaps in a picture In addition to specifying the 2D array of data you also specify the color table for corresponding array values to colors The 2D array corresponds to a grid of pixels These VIs convert each value in the data array into a color by using the value as an index into the color table array The last row of the Picture Functions palette contains the Empty Picture constant which you use whenever you need to start with or make changes to an empty picture National Instruments Corporation 12 5 LabVIEW User Manual Chapter 12 Graphics and Sound VIs Creating and Modifying Colors with the Picture Functions Vis Many of the Picture Functions VIs have a color input to modify the color of the shapes and text The easiest way to create a color is to use a color box constant located on the Functions Numeric Additional Numeric Constants palette and click the constant to select a color To create colors as the result of calculations rather than with color box constants you need to understand how a color box specifies a color using a numeric value A 32 bit signed integer represents a color and the lower three bytes represent the red green and blue components of the color For a range of blue colors create an array of 32 bit integers where only the values of the low bytes change because the low byte contains the blue compo
144. e default value from passing into the While Loop by using the Array Size function The Array Size function indicates how many elements are in the array Set up the While Loop to stop executing when it has iterated the same number of times as the array size UN Caution Because you cannot determine the size of the output array in advance enabling auto indexing for the output of a For Loop is more efficient than with a While Loop Iterating too many times can cause your system to run out of memory Shift Registers in Loops Use shift registers on For Loops and While Loops to transfer values from one loop iteration to the next Shift registers are similar to static variables in text based programming languages FE A shift register appears as a pair of terminals shown at left directly opposite each other on the vertical sides of the loop border The right terminal contains an up arrow and stores data on the completion of an iteration LabVIEW transfers the data connected to the right side of the register to the next iteration Create a shift register by right clicking the left or right border of a loop and selecting Add Shift Register from the shortcut menu National Instruments Corporation 8 5 LabVIEW User Manual Chapter 8 Loop and Case Structures Controlling Timing A shift register transfers any data type and automatically changes to the data type of the first object wired to the shift register The data you wire to the terminals of
145. e File function The Close File function does not run until it receives the output of the Read File function Data Flow and Managing Memory Dataflow execution makes managing memory easier than the control flow model of execution In LabVIEW you do not allocate variables or assign values to them Instead you create a block diagram with wires that represent the transition of data VIs and functions that generate data automatically allocate the memory for that data When the VI or function no longer uses the data LabVIEW deallocates the associated memory When you add new data to an array or a string LabVIEW allocates enough memory to manage the new data Because LabVIEW automatically handles memory management you have less control over when memory is allocated or deallocated If your VI works with large sets of data you need to understand when memory allocation takes place Understanding the principles involved can help you write VIs with significantly smaller memory requirements Minimizing National Instruments Corporation 5 21 LabVIEW User Manual Chapter 5 Building the Block Diagram memory usage can help you increase the speed at which VIs run Refer to the LabVIEW Performance and Memory Management Application Note for more information about memory allocation Designing the Block Diagram LabVIEW User Manual Use the following guidelines to design block diagrams Use a left to right and top to bottom layou
146. e LabVIEW run time engine and the user at the server computer creates an HTML file that includes an lt OBJECT gt tag that 17 12 ni com Chapter 17 Networking in LabVIEW references the VI you want clients to view and control This tag contains a URL reference to a VI and information that directs the Web browser to pass the VI to the LabVIEW browser plug in Clients navigate to the Web Server by entering the Web address of the Web Server in the address or URL field at the top of the Web browser window The plug in displays the front panel in the Web browser window and communicates with the Web Server so the client can interact with the remote front panel Clients request control by selecting Request Control of the VI at the bottom of the remote front panel window in their Web browser or by right clicking anywhere on the front panel and selecting Request Control of the VI from the shortcut menu 3 Note National Instruments recommends that you use Netscape 4 7 or later or Internet Explorer 5 0 or later when viewing and controlling front panels in a Web browser Functionality Not Supported in Viewing and Controlling Remote Front Panels Because of the constraints of a Web browser user interface applications that attempt to manipulate the dimensions and location of a front panel do not work properly when that front panel is displayed as a part of a Web page Although the Web Server and the LabVIEW browser plug in attempt to preserve the fidelity
147. e Loop and a terminating condition stops the While Loop you can continue to generate events but the Event structure does not execute and handle them This can cause your user interface to lock ny Note If you build a VI that contains an Event structure using the Full or Professional Development Systems you can run that VI in the LabVIEW Base Package and LabVIEW retains the Event structure functionality However you cannot edit the Event structure in the LabVIEW Base Package I Time LabVIEW User Manual Use the Timeout terminal at the top left of the Event structure shown at left to specify the number of milliseconds an Event structure waits until an event occurs The default is 1 which means to wait indefinitely If the timeout expires before an event occurs and you have configured a case to handle the timeout event LabVIEW generates a timeout event The Event Data Node shown at left is similar in appearance to the Unbundle By Name function This node is attached to the inside left and right borders of each event case You can resize this node vertically and you 8 12 ni com Chapter 8 Loop and Case Structures can set each element in the node to access an arbitrary Event Data Field like you can with the Unbundle By Name function The node displays data that is different in each case of the Event structure depending on which event s you configure that case to handle If you configure a single case to handle multiple even
148. e and place a local variable on the block diagram The local variable node shown at left is not yet associated with a control or indicator Right click the local variable node and select a front panel object from the Select Item shortcut menu The shortcut menu lists all the front panel objects that have owned labels LabVIEW uses owned labels to associate local variables with front panel objects so label the front panel controls and indicators with descriptive owned labels Refer to the Labeling section of Chapter 4 Building the Front Panel for more information about owned and free labels Global Variables Use global variables to access and pass data among several VIs that run simultaneously Global variables are built in LabVIEW objects When you create a global variable LabVIEW automatically creates a special global VI which has a front panel but no block diagram Add controls and indicators to the front panel of the global VI to define the data types of the global variables it contains In effect this front panel is a container from which several VIs can access data For example suppose you have two VIs running simultaneously Each VI contains a While Loop and writes data points to a waveform chart The first VI contains a Boolean control to terminate both VIs You must use a global variable to terminate both loops with a single Boolean control If both loops were on a single block diagram within the same VI you could use a local
149. e available the probe immediately updates during single stepping or when you pause at a breakpoint When execution pauses at a node because of single stepping or a breakpoint you also can probe the wire that just executed to see the value that flowed through that wire You also can create a custom probe to specify which indicator you use to view the probed data For example if you are viewing numeric data you 6 4 ni com Chapter 6 Running and Debugging Vis can choose to see that data in a chart within the probe Right click a wire and select Custom Probe then specify the indicator you want to use Breakpoints Use the Breakpoint tool shown at left to place a breakpoint on a VI node or wire on the block diagram and pause execution at that location When you set a breakpoint on a wire execution pauses after data pass through the wire Place a breakpoint on the block diagram workspace to pause execution after all nodes on the block diagram execute When a VI pauses at a breakpoint LabVIEW brings the block diagram to the front and uses a marquee to highlight the node or wire that contains the breakpoint When you move the cursor over an existing breakpoint the black area of the Breakpoint tool cursor appears white When you reach a breakpoint during execution you can take the following actions e Single step through execution using the single stepping buttons e Probe wires to check intermediate values e Continue running to
150. e bounds of an array produces the default value for the array element parameter You can use the Array Size function to determine the size of the array Refer to the Arrays section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about arrays Refer to the Auto Indexing Loops section of Chapter 8 Loop and Case Structures for more information about indexing You can index beyond the bounds of an array inadvertently by indexing an array past the last element using a While Loop by supplying too large a value to the index input of an Index Array function or by supplying an empty array to an Index Array function Preventing Undefined Data Do not rely on special values such as NaN Inf or empty arrays to determine if a VI produces undefined data Instead confirm that the VI produces defined data by making the VI report an error if it encounters a situation that is likely to produce undefined data For example if you create a VI that uses an incoming array to auto index a For Loop determine what you want the VI to do when the input array is empty Either produce an output error code or substitute defined data for the values that the loop creates Error Checking and Error Handling LabVIEW User Manual Debugging which is enabled automatically in LabVIEW checks the block diagram nodes for errors You can verify the debugging setting by selecting File VI Properties and selecting Execution in the Catego
151. e click double click or triple click them Single clicking a wire selects one segment of the wire Double clicking a wire selects a branch Triple clicking a wire selects the entire wire Removing Broken Wires A broken wire appears as a dashed black line Broken wires occur for a variety of reasons such as when you try to wire two objects with incompatible data types Move the Wiring tool over a broken wire to view a tip strip that describes why the wire is broken Triple click the wire with the Positioning tool and press the lt Delete gt key to remove a broken wire Sy Note Do not confuse a dashed black wire with a dotted green wire A dotted green wire represents a Boolean data type You can remove all broken wires by selecting Edit Remove Broken Wires UN Caution Use caution when removing all broken wires Sometimes a wire appears broken because you are not finished wiring the block diagram Coercion Dots LabVIEW User Manual Coercion dots appear on block diagram nodes to alert you that you wired two different data types together The dot means that LabVIEW converted the value passed into the node to a different representation For example if you wire a control with a double precision floating point representation value of 3 02 into an indicator with an integer representation a coercion dot appears on the indicator and the indicator is 3 5 12 ni com Chapter 5 Building the Block Diagram The block diagram places a co
152. e information about the types of elements an array can contain Refer to the Clusters section for more information about clusters Indexes To locate a particular element in an array requires one index per dimension In LabVIEW indexes let you navigate through an array and retrieve elements rows columns and pages from an array on the block diagram Examples of Arrays An example of a simple array is a text array that lists the nine planets of our solar system LabVIEW represents this as a 1D array of strings with nine elements Array elements are ordered An array uses an index so you can readily access any particular element The index is zero based which means it is in the range 0 to n 1 where n is the number of elements in the array For example n 9 for the nine planets so the index ranges from 0 to 8 Earth is the third planet so it has an index of 2 9 8 ni com Chapter 9 Grouping Data Using Strings Arrays and Clusters Another example of an array is a waveform represented as a numeric array in which each successive element is the voltage value at successive time intervals as shown in Figure 9 3 index 0 1 2 3 4 5 6 r 8 volts 0 4 0 9 1 4 0 8 0 1 0 7 0 3 0 3 0 2 Figure 9 3 Waveform in an Array of Numerics A more complex example of an array is a graph represented as an array of points where each point is a cluster containing a pair of numerics
153. e knobs dials gauges and meters The rotary objects operate similarly to the slide controls and indicators Change the value of a rotary control or indicator by moving the needles by clicking a point of the rotary object or by using the optional digital display Rotary controls or indicators can display more than one value Right click the object and select Add Needle from the shortcut menu to add new needles The data type of a control with multiple needles is a cluster that contains each of the numeric values Refer to the Clusters section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about clusters LabVIEW User Manual 4 8 ni com Chapter 4 Building the Front Panel Digital Controls and Indicators Digital controls and indicators are the simplest way to enter and display numeric data You can resize these front panel objects horizontally to accommodate more digits You can change the value of a digital control or indicator by using the following methods e Use the Operating or Labeling tool to click inside the digital display window and enter numbers from the keyboard e Use the Operating tool to click the increment or decrement arrow buttons of a digital control e Use the Operating or Labeling tool to place the cursor to the right of the digit you want to change and press the up or down arrow key on the keyboard Color Boxes A color box displays a color that corresponds to a specified
154. e network and your local computer e File Transfer Protocol tp You can use this protocol to specify a file from which to read data e file You can use this protocol to provide a link to a local or network file that contains data National Instruments Corporation 17 3 LabVIEW User Manual Chapter 17 Networking in LabVIEW Table 17 1 shows examples of each protocol URL Table 17 1 Example DataSocket URLs URL Example dstp dstp servername com numeric where numeric is the named tag for the data ope ope National Instruments OPCTest item1 opc machine National Instruments OPCModbus Modbus Demo Box 4 0 opc machine National Instruments OPCModbus Modbus Demo Box 4 0 updaterate 100 amp deadband 0 7 logos logos computer_name process data_item_ name ftp ftp ftp ni com datasocket ping wav file file ping wav file c mydata ping wav file machine mydata ping wav Use the dstp opc and logos URLs to share live data because these protocols can update remote and local controls and indicators Use the ftp and file URLs to read data from files because these protocols cannot update remote and local controls and indicators Refer to the examples comm datasktx 11b for examples of using DataSocket connections Data Formats Supported by DataSocket Use DataSocket to publish and subscribe to the following data LabVIEW User Manual Raw text Use raw text to deliver a string to a
155. each shift register must be the same type You can create multiple shift registers on a structure and you can have more than one left terminal to remember more than one previous value After the loop executes the last value stored in the shift register remains at the right terminal If you wire the right terminal outside the loop the wire transfers the last value stored in the shift register If you do not initialize the register the loop uses the value written to the register when the loop last executed or the default value for the data type if the loop has never executed Use a loop with an uninitialized shift register to run a VI repeatedly so that each time the VI runs the initial output of the shift register is the last value from the previous execution Use an uninitialized shift register to preserve state information between subsequent executions of a VI You might want to control the speed at which a process executes such as the speed at which data are plotted to a chart You can use a wait function in the loop to wait an amount of time in milliseconds you want to wait before the loop re executes Case and Sequence Structures Case Structures Tie gt Ml True P LabVIEW User Manual Case Sequence and Event structures contain multiple subdiagrams only one of which is visible at a time A Case structure executes one subdiagram depending on the input value passed to the structure A Sequence structure executes a
156. ecify in the LicenseErrorMessage txt file in labview www In this message you might want to include information about who the client should contact such as the server administrator or the person in your organization responsible for upgrading the remote panel license If you do not enter anything in this file a default error message appears on the client computer indicating that their connection request was denied 3 Note Although you can use any LabVIEW development system to build VIs that clients can view and control remotely only the Full and Professional Development Systems support viewing and controlling those VIs remotely National Instruments Corporation 17 11 LabVIEW User Manual Chapter 17 Networking in LabVIEW Viewing and Controlling Front Panels in LabVIEW or from a Web Browser A client can view and control a front panel remotely from LabVIEW or from a Web browser ay Note Before you can view and control a front panel remotely you must enable the Web Server on the server computer where the VI you want to view and control is located LabVIEW User Manual Viewing and Controlling Front Panels in LabVIEW To view a remote front panel using LabVIEW as a client open a new VI and select Operate Remote Panel Connect to display the Open Remote Panel dialog box Use this dialog box to specify the server Internet address and the VI you want to view By default the remote VI front panel is initially in observer mode You can r
157. ects of the test as it progresses and finally allows the user to display and store only pertinent data On the block diagram the tab control is an enumerated type control by default Terminals for controls and indicators placed on the tab control appear as any other block diagram terminal Refer to the Enumerated Type Controls section of this chapter for more information about enumerated type controls Use the listbox controls located on the Controls List amp Table and Controls Classic Controls List amp Table palettes to give users a list of items from which to select You can configure listboxes to accept single or multiple selections Use the multicolumn listbox to display more information about each item such as the size of the item and the date it was created Use the Property Node of the listbox control to modify list items and to gather information about list items in the following ways e Set item strings e Add a symbol next to the list item as in the Save dialog box where directories and files have different symbols e Disable individual items in the list e Insert separator lines between list items e Detect currently selected items by reading the value of the control e Detect which items if any the user double clicked Refer to the Property Nodes section of Chapter 16 Programmatically Controlling VIs for more information about Property Nodes Listboxes support type completion which means that you type
158. ects to the center of the terminal regardless of where you click the terminal After you click the terminal switch between horizontal and vertical direction by pressing the spacebar 5 10 ni com Chapter 5 Building the Block Diagram While you are wiring a terminal bend the wire at a 90 degree angle once by moving the cursor in either a vertical or horizontal direction To bend a wire in multiple directions click the mouse button to set the wire and then drag the wire in the new direction You can repeatedly set the wire and drag it in new directions To undo the last point where you set the wire press the lt Shift gt key and click anywhere on the block diagram Macintosh Press the lt Option gt key and click UNIX and Linux Click the middle mouse button When you cross wires a small gap appears in the first wire you drew to indicate that the first wire is under the second wire UN Caution Crossing wires can clutter a block diagram and make the block diagram difficult to debug Automatically Wiring Objects If you have automatic wiring enabled LabVIEW automatically wires objects as you place them on the block diagram You also can automatically wire objects already on the block diagram LabVIEW connects the terminals that best match and leaves terminals that do not match unconnected As you move a selected object close to other objects on the block diagram LabVIEW draws temporary wires to show you valid connections Wh
159. ed The connector pane has at most 28 terminals If your front panel contains more than 28 controls and indicators that you want to use programmatically group some of them into a cluster and assign the cluster to a terminal on the connector pane Although cluster and array elements are both ordered you must unbundle all cluster elements at once rather than index one element at a time You also can use the Unbundle By Name function to access specific cluster elements Clusters also differ from arrays in that they are a fixed size Like an array a cluster is either a control or an indicator A cluster cannot contain a mixture of controls and indicators Most clusters on the block diagram have a pink wire pattern and data type icon Clusters of numerics sometimes referred to as points have a brown wire pattern and data type icon You can wire brown numeric clusters to Numeric functions such as Add or Square Root to perform the same operation simultaneously on all elements of the cluster Cluster elements have a logical order unrelated to their position in the shell The first object you place in the cluster is element 0 the second is element 1 and so on If you delete an element the order adjusts automatically The cluster order determines the order in which the elements appear as terminals on the Bundle and Unbundle functions on the block diagram You can view and modify the cluster order by right clicking the cluster border and selecting
160. ed VIs for a specific use Mechanism for controlling VIs and LabVIEW applications programmatically locally and remotely Program in LabVIEW that models the appearance and function of a physical instrument VISA Single interface library for controlling GPIB VXI RS 232 and other types of instruments See Virtual Instrument Software Architecture VME eXtensions for Instrumentation bus LabVIEW User Manual Glossary W waveform waveform chart While Loop wire wire bend wire branch wire junction wire segment wire stubs Wiring tool LabVIEW User Manual Multiple voltage readings taken at a specific sampling rate Indicator that plots data points at a certain rate Loop structure that repeats a section of code until a condition is met Data path between nodes Point where two wire segments join Section of wire that contains all the wire segments from junction to junction terminal to junction or terminal to terminal if there are no junctions between Point where three or more wire segments join Single horizontal or vertical piece of wire Truncated wires that appear next to unwired terminals when you move the Wiring tool over a VI or function node Tool to define data paths between terminals G 16 ni com Index Numerics 2D controls and indicators 4 7 3D controls and indicators 4 7 3D graphs 11 15 A ActiveX 18 1 accessing ActiveX enabled applications 18 3 building subpalette
161. ed the file remains in the Windows configuration settings file format configuration file path Lo temp data ini Close Config Data vi Figure 13 6 Reading Data from an ini File Windows Configuration Settings File Format Windows configuration settings files are text files divided into named sections Brackets enclose each section name Every section name in a file must be unique The sections contain key value pairs separated by an equal sign Within each section every key name must be unique The key name represents a configuration preference and the value name represents the setting for that preference The following example shows the arrangement of the file Section 1 keyl value key2 value Section 2 keyl value key2 value National Instruments Corporation 13 13 LabVIEW User Manual Chapter 13 File 1 0 LabVIEW User Manual Use the following data types with Configuration File VIs for the value portion of the key parameter e String e Path e Boolean e 64 bit double precision floating point numeric e 32 bit signed integer e 32 bit unsigned integer The Configuration File VIs can read and write raw or escaped string data The VIs read and write raw data byte by byte without converting the data to ASCII In converted or escaped strings LabVIEW stores any non displayable text characters in the configuration settings file with the equivalent hexadecimal escape codes such as oD for
162. ee the LabVIEW Help dstp DataSocket protocol 17 3 Dynamic Data Exchange 17 15 LabVIEW User Manual Index E editing front panel objects 4 1 labels See the LabVIEW Help menus 15 2 palette views 3 5 shortcut menus of polymorphic VIs See the LabVIEW Help embedding objects using ActiveX 18 4 empty paths 4 11 enumerated type controls 4 13 advanced 4 13 data type table 5 2 using See the LabVIEW Help equations Expression Nodes 20 4 Formula Nodes 20 2 HiQ ActiveX 20 2 debugging scripts 20 6 script node 20 5 VIs 20 5 integrating into LabVIEW 20 1 MATLAB ActiveX 20 2 debugging scripts 20 6 script node 20 5 methods for using 20 1 errors broken VIs 6 2 canceling existing See the LabVIEW Help checking for 6 9 clusters 6 9 components 6 10 connector pane 7 6 reports See the LabVIEW Help codes 6 9 debugging techniques 6 3 defining custom See the LabVIEW Help LabVIEW User Manual I 10 displaying 6 2 exception control See the LabVIEW Help finding 6 2 handling 6 8 instrument control See the LabVIEW Help methods 6 9 using Case structures 6 10 using While Loops 6 10 T O 6 9 list 6 2 normal conditions as See the LabVIEW Help notification See the LabVIEW Help units incompatible 5 18 window 6 2 Event structures 8 12 using See the LabVIEW Help events ActiveX 18 1 available in LabVIEW See the LabVIEW Help filter 8 13 handling 8 12 caveats See the LabVIEW He
163. eeeeseeseeeseeseceseeaeensesneenaes 4 7 3D and Classic Controls and Indicators ee eeeeseeseceeeeeceeeeeeeeeeseeenees 4 7 Slides Knobs Dials and Digital Displays eee cece eseeeeteeeeeeeseeenees 4 8 Slide Controls and Indicators 00 eee eseeseceeeeneeeseceeeneeeseeenees 4 8 Rotary Controls and Indicators eee eeeeseeeeceeeeeeeeeeseeseeeseeesees 4 8 Digital Controls and Indicators eee eeeeseeeseeeseeeeeeeseeeseenees 4 9 GOJOE BOXE Saien eves as teeme eels esos E ERER 4 9 Color Ramps ar n 4 Resa etal ece es se ates Seed eaueah dee ea 4 9 Buttons Switches and Lights ee eescessecssecesceeseceseeeeeeceeeeeeeeaeeeseeeeaeeaes 4 10 Text Entry Boxes Labels and Path Displays 0 0 0 ee eeeeseeeeeeeeeseeeeeeneeees 4 10 String Controls and Indicators 00 eee ee eeeeseceeeeseeeeeeseeseeeseeseees 4 10 Path Controls and Indicators eee eseeeeseceeceeeeeeeseseeeeeeeseeenees 4 10 Invalid Paths cise Sey ceccstet SE EET AEAEE 4 11 Empty Paths koreton na ean EARE O E E 4 11 LabVIEW User Manual vi ni com Contents Array and Cluster Controls and Indicators ee eeeeseeseceeesseeeeeseeeeeeseenees 4 11 TabControl Snan gn n nn oni porai isha 4 11 EistboRE Srii ea en E hate ih ota ied E ES 4 12 Ring and Enumerated Type Controls and Indicators sssesseeeseeeeeeeeseeereeeee 4 13 Ring Comtesse ci ci ses 2skess na tedenne ien aves E E AE teste teas EAN 4 13 Enumerated Type Controls 0 0 eee eceeseeseeseeseeeseceeceeeeeeeseseeeenees
164. elp customizing appearance 11 3 customizing behavior 11 3 digital 11 13 masking data 11 15 graphics 12 3 intensity 11 11 options 11 13 multiple scales 11 2 options 11 2 polar 12 3 scales formatting 11 5 scaling 11 5 Smith plots 12 4 smooth updates 11 5 transmission lines 12 4 types 11 1 waveform 11 7 data types 11 8 XY 11 7 data types 11 9 11 10 zooming See the LabVIEW Help grouping data arrays 9 8 clusters 9 13 strings 9 1 front panel objects 4 5 VIs in libraries 7 10 guidelines for development 1 2 H help technical support E 1 help files 1 2 creating your own 14 4 HTML 14 4 LabVIEW User Manual 1 14 linking to VIs See the LabVIEW Help RTF 14 4 hidden front panel objects See the LabVIEW Help hiding front panel objects See the LabVIEW Help menu bar 4 16 optional elements in front panel objects 4 2 scroll bars 4 16 Hierarchy Window 7 9 printing 14 3 searching See the LabVIEW Help highlighting execution debugging VIs 6 4 HiQ ActiveX 20 2 data types 20 6 debugging scripts 20 6 launching from LabVIEW 20 5 script node 20 5 support files for LabVIEW applications 20 7 VIs 20 5 history See also revision history charts 11 6 options 3 6 hot menus See the LabVIEW Help HTML See also Web creating documents 17 9 graphics formats 14 4 help files 14 4 printing reports 14 5 publishing VIs on Web 17 9 saving to 14 3 ni com T O c
165. elp datalogging 13 15 LabVIEW User Manual I 12 DataSocket 17 5 defining window size See the LabVIEW Help deleting objects See the LabVIEW Help designing 4 18 displaying optional object elements 4 2 displaying with different screen resolutions 4 19 distributing objects See the LabVIEW Help finding objects See the LabVIEW Help fonts 4 17 grouping and locking objects 4 5 hidden objects See the LabVIEW Help hiding objects See the LabVIEW Help optional object elements 4 2 importing graphics 4 4 indicators 4 7 inserting objects using ActiveX 18 4 keyboard shortcuts 4 3 labels 4 16 creating See the LabVIEW Help editing See the LabVIEW Help resizing See the LabVIEW Help logging data 13 15 objects block diagram terminals and 5 1 options 3 6 order of objects 4 4 overlapping objects 4 11 planning 7 1 printing 14 5 publishing images on Web 17 10 removing objects See the LabVIEW Help reordering objects See the LabVIEW Help replacing objects 4 2 resizing objects 4 5 in relation to window size 4 5 ni com National Instruments Corporation retrieving data using file I O functions 13 18 using subVIs 13 17 scaling objects 4 5 setting navigation order 4 4 spacing objects evenly See the LabVIEW Help subVIs 7 8 text characteristics 4 17 transparent objects See the LabVIEW Help type definitions 4 1 viewing remotely 17 10 ftp DataSocket protocol 17 3 function key setti
166. els to show to prospective users or project team members and determine if the front panel helps your users accomplish their tasks Use this interactive process to refine the user interface as necessary Divide your application into manageable pieces at logical places Begin with a high level block diagram that includes the main components of your application For example the block diagram could include a block for configuration a block for acquisition a block for analysis of the acquired data a block for displaying analysis results a block for saving the data to disk and a block to handle errors After you design the high level block diagram define the inputs and outputs Then design the subVIs that make up the main components of the high level block diagram Using subVIs makes the high level block National Instruments Corporation 7 1 LabVIEW User Manual Chapter 7 Creating Vis and SubVIs diagram easy to read debug understand and maintain You also can create subVIs for common or frequent operations that you can reuse Test subVIs as you create them You can create higher level test routines but catching errors in a small module is easier than testing a hierarchy of several VIs You might find that the initial design of the high level block diagram is incomplete Using subVIs to accomplish low level tasks makes it easier to modify or reorganize your application Refer to the SubVIs section of this chapter for more information abou
167. en you release the mouse button to place the object on the block diagram LabVIEW automatically connects the wires Toggle automatic wiring by pressing the space bar while you move an object using the Positioning tool By default automatic wiring is enabled when you select an object from the Functions palette or when you copy an object already on the block diagram by pressing the lt Ctrl gt key and dragging the object Automatic wiring is disabled by default when you use the Positioning tool to move an object already on the block diagram Macintosh Press the lt Option gt key Sun Press the lt Meta gt key Linux Press the lt Alt gt key National Instruments Corporation 5 11 LabVIEW User Manual Chapter 5 Building the Block Diagram Manually Wiring Objects Selecting Wires Use the Wiring tool to manually connect the terminals on one block diagram node to the terminals on another block diagram node The cursor point of the tool is the tip of the unwound wire spool When you move the Wiring tool over a node the terminal blinks and on VIs and functions the name of the terminal appears in a tip strip Select Help Show Context Help to display the Context Help window which lists each terminal of the VI or function to show you exactly where wires must connect The Context Help window does not display terminals for expandable functions such as the Build Array function Select wires by using the Positioning tool to singl
168. en plot the data to the graph which is similar to a spreadsheet that first stores the data then generates a plot of it In contrast a chart appends new data points to those already in the display On a chart you can see the current reading or measurement in context with data previously acquired For more information Refer to the LabVIEW Help for more information about using graphs and charts Types of Graphs and Charts The graphs and charts located on the Controls Graph palette include the following types e Waveform Chart and Graph Displays data acquired at a constant rate XY Graph Displays data acquired at a non constant rate such as data acquired when a trigger occurs Intensity Chart and Graph Displays 3D data on a 2D plot by using color to display the values of the third dimension Digital Waveform Graph Displays data as pulses or groups of digital lines Computers transfer digital data to other computers in pulses Windows 3D Graphs Displays 3D data on a 3D plot in an ActiveX object on the front panel Refer to examples general graphs for examples of graphs and charts National Instruments Corporation 11 1 LabVIEW User Manual Chapter 11 Graphs and Charts Graph and Chart Options Although graphs and charts plot data differently they have several common options that you access from the shortcut menu Refer to the Customizing Graphs and Customizing Charts sections of this chapter for
169. enting and Printing Vis Revision numbers are independent of comments in the History window Gaps in revision numbers between comments indicate that you saved the VI without a comment Because the history is strictly a development tool LabVIEW automatically removes the history when you remove the block diagram of a VI Refer to the Distributing VIs section of Chapter 7 Creating VIs and SubVIs for more information about removing the block diagram The History window is not available in the run time version of a VI The General page of the VI Properties dialog box displays the revision number even for VIs without block diagrams Click the Reset button in the History window to erase the revision history and reset the revision number to zero Printing Documentation Select File Print to print VI documentation or save it to HTML or RTF files You can select a built in format or create a custom format for documentation The documentation you create can include the following items e Connector pane and icon e Front panel and block diagram e Controls indicators and data types e VI hierarchy e List of subVIs e Revision history Saving to HTML or RTF Files You can save VI documentation to HTML or RTF files You can import HTML and RTF files into most word processing applications and you can use HTML and RTF files to create compiled help files You also can use the HTML files LabVIEW generates to display VI documentation on the Web Re
170. environment are sent to DAQ devices Terminal to pass data between the frames of a Sequence structure Program control structure that executes its subdiagrams in numeric order Use this structure to force nodes that are not data dependent to execute in the order you want Optional mechanism in loop structures to pass the value of a variable from one iteration of a loop to a subsequent iteration Shift registers are similar to static variables in text based programming languages Menu accessed by right clicking an object Menu options pertain to that object specifically Moveable part of slide controls and indicators LabVIEW User Manual Glossary string string controls and indicators strip chart structure subdiagram subVI sweep chart syntax T TCP terminal tip strip tool toolbar Tools palette top level VI tunnel LabVIEW User Manual Representation of a value as text Front panel objects to manipulate and display text Numeric plotting indicator modeled after a paper strip chart recorder which scrolls as it plots data Program control element such as a Sequence structure Case structure For Loop or While Loop Block diagram within the border of a structure VI used on the block diagram of another VI Comparable to a subroutine Numeric indicator modeled on the operation of an oscilloscope It is similar to a scope chart except that a line sweeps across the display to separate old
171. eparate owned label called the unit label Display the unit label by right clicking the control and selecting Visible Items Unit Label from the shortcut menu When LabVIEW displays the unit label you can enter a unit using standard abbreviations such as m for meters ft for feet s for seconds and so on 3 Note You cannot use units in Formula Nodes National Instruments Corporation 5 17 LabVIEW User Manual Chapter 5 Building the Block Diagram Units and Strict Type Checking When you associate units with an object you can wire only objects that have compatible units LabVIEW uses strict type checking to verify that units are compatible If you wire two objects with incompatible units LabVIEW returns an error For example LabVIEW returns an error if you wire an object with mile as its unit type to an object with liter as its unit type because a mile is a unit of distance and a liter is a unit of volume Figure 5 5 shows wiring objects with compatible units In this figure LabVIEW automatically scales the distance indicator to display kilometers instead of meters because kilometers is the unit for the indicator speed 0 00 nfs distance 0 00 s time 2 0 00 s LabVIEW User Manual Figure 5 5 Wiring Objects with Compatible Units 5 18 ni com Chapter 5 Building the Block Diagram An error occurs in Figure 5 6 because distance has a unit type of seconds To correct the error change seconds to a unit o
172. epresentation LabVIEW converts the data according to the following rules e Signed or unsigned integer to floating point number Conversion is exact except for long integers to single precision floating point numbers In this case LabVIEW reduces the precision from 32 bits to 24 bits e Floating point number to signed or unsigned integer Lab VIEW moves out of range values to the integer s minimum or maximum value Most integer objects such as the iteration terminal of a For Loop round floating point numbers LabVIEW rounds a fractional part of 0 5 to the nearest even integer For example LabVIEW rounds 6 5 to 6 rather than 7 e Integer to integer LabVIEW does not move out of range values to the integer s minimum or maximum value If the source is smaller than the destination LabVIEW extends the sign of a signed source and places zeros in the extra bits of an unsigned source If the source is larger than the destination LabVIEW copies only the least significant bits of the value Polymorphism for Numeric Functions LabVIEW User Manual The arithmetic functions take numeric input data With some exceptions noted in the function descriptions the output has the same numeric representation as the input or if the inputs have different representations the output is the wider of the inputs The arithmetic functions work on numbers arrays of numbers clusters of numbers arrays of clusters of numbers complex numbers and s
173. equest control by placing a checkmark in the Request Control of the VI checkbox in the Open Remote Panel dialog box when you request a VI When the VI appears on your computer right click anywhere on the front panel and select Request Control of the VI from the shortcut menu You also can access this menu by clicking the status bar at the bottom of the front panel window If no other client is currently in control a message appears indicating that you have control of the front panel If another client is currently controlling the VI the server queues your request until the other client relinquishes control Only the user at the server computer can monitor the client queue list by selecting Tools Remote Panel Connection Manager All VIs you want clients to view and control must be in memory If the requested VI is in memory the server sends the front panel of the VI to the requesting client If the VI is not in memory the Connection Status section of the Open Remote Panel dialog box displays an error message Viewing and Controlling Front Panels from a Web Browser If you want clients who do not have LabVIEW installed to be able to view and control a front panel remotely using a Web browser they must install the LabVIEW Run Time Engine The LabVIEW Run Time Engine includes a LabVIEW browser plug in package that installs in the browser plug in directory The LabVIEW CD contains an installer for the LabVIEW Run Time Engine Clients install th
174. er 4 Building the Front Panel for more information about color ramps You can set the color mapping for the intensity graph and chart programmatically by using the Property Node in two ways Typically you specify the value to color mappings in the Property Node For this method specify the Z Scale Marker Values property This property consists of an array of clusters in which each cluster contains a numeric limit value and the corresponding color to display for that value When you specify the color mapping in this manner you can specify an upper out of range color using the Z Scale High Color property and a lower out of range color using the Z Scale Low Color property The intensity graph and chart is limited to a total of 254 colors with the lower and upper out of range colors bringing the total to 256 colors If you specify more than 254 colors the intensity graph or chart creates the 254 color table by interpolating among the specified colors If you display a bitmap on the intensity graph you specify a color table using the Color Table property With this method you can specify an array of up to 256 colors Data passed to the chart are mapped to indexes in this color table based on the color scale of the intensity chart If the color scale ranges from 0 to 100 a value of 0 in the data is mapped to index 1 anda value of 100 is mapped to index 254 with interior values interpolated between and 254 Anything below 0 is mapped to the
175. er for more information about adding shift registers to a loop Avoiding Infinite While Loops If you place the terminal of the Boolean control outside the While Loop as shown in Figure 8 1 and the control is set to FALSE if the conditional terminal is Stop If True when the loop starts you cause an infinite loop You also cause an infinite loop if the control outside the loop is set to TRUE and the conditional terminal is Continue If True Figure 8 1 Infinite While Loop Changing the value of the control does not stop the infinite loop because the value is only read once before the loop starts To stop an infinite loop you must abort the VI by clicking the Abort button on the toolbar National Instruments Corporation 8 3 LabVIEW User Manual Chapter 8 Loop and Case Structures Auto Indexing Loops LabVIEW User Manual If you wire an array to a For Loop or While Loop input tunnel you can read and process every element in that array by enabling auto indexing Refer to Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about arrays When you wire an array to an input tunnel on the loop border and enable auto indexing on the input tunnel elements of that array enter the loop one at a time starting with the first element When auto indexing is disabled the entire array is passed into the loop When you auto index an array output tunnel the output array receives a new element from ever
176. erations when Using Local Variables s ssssessssssesesesese 10 5 Memory Considerations when Using Global Variables 0 cece 10 5 Chapter 11 Graphs and Charts Eypes of Graphs and Charts a tibet dues dee Adee eevee teed 11 1 Graph and Chart Options vies idee a ioed e e E Damen ete tern eer 11 2 Multiple X and Y Scales on Graphs and Chat ts 0 0 0 0 ec ceeeeeseeeeseeeeeeeeeees 11 2 Anti Aliased Line Plots for Graphs and Charts ec ceecssesseeseeeseeeeeseeeees 11 2 Customizing Graph and Chart Appearance 0 eee eeeeseeseceeeeneeeeeeseeneeeaees 11 3 Customizing Graphs ise siccecs sissies eons duceede cy cocdvissutdesevessevduss pesto vasssvessdedeeseesisboveus 11 3 Graph CULSOTS ee e ob nT N A tegen Maat ea age ase dd 11 4 Scale Options iniuria E AR E E R cus dette ch oet sets 11 5 Waveform Graph Scale Legend ssssesseseesereeeereererrersreseee 11 5 Graph Scale Formatting sssi iecerei e ieridiuiipdi diii diinn 11 5 Using Smooth Updates nsei A a 11 5 Customizing CHAS en E a E E E E E S RS 11 6 Chart History Length s cisca iia tnd Manliiadtoiihiiiaiednid 11 6 Chart Update Modesasiccss cteevstes eas eves EE E E NEES 11 6 Overlaid Versus Stacked Plots sssesseeeeeesseeesssesresrsrrsresrsresrsresreeese 11 6 Waveform and XY Graphs 6 9 5 5 ancien ete dots te te E A EOR dekeaaers 11 7 Single Plot Waveform Graph Data Types cece ceeeseeseeeeseeeeseeeeeeneeaeens 11 8 Multiplot Waveform Graph
177. ercion dot on the border of a terminal where the conversion takes place to indicate that automatic numeric conversion occurred Because VIs and functions can have many terminals a coercion dot can appear inside an icon if you wire through one terminal to another terminal as shown in the following example Coercion dots can cause a VI to use more memory and increase its run time Try to keep data types consistent in your VIs Polymorphic Vis and Functions Polymorphic VIs and functions can adjust to input data of different data types Most LabVIEW structures are polymorphic as are some VIs and functions Polymorphic Vis Polymorphic VIs accept different data types for a single input or output terminal A polymorphic VI is a collection of subVIs with the same connector pane patterns Each subVI is an instance of the polymorphic VI For example the Read Key VI is polymorphic Its default value terminal accepts Boolean double precision floating point numeric signed 32 bit integer numeric path string or unsigned 32 bit integer numeric data The data types you wire to the inputs of a polymorphic VI determine the instance to use If the polymorphic VI does not contain a subVI for that data type a broken wire appears You can select the instance you want to act as the default instance by right clicking the polymorphic VI selecting Select Type from the shortcut menu and selecting the subVI National Instruments C
178. erent log file by selecting Operate Data Logging Change Log File Binding LabVIEW prompts you to select a different log file or to create a new one You might change log file binding when you want to retrieve different data into a VI or append data from the VI to another datalog file Retrieving Front Panel Data Programmatically You also can retrieve logged data using a subVI or using the File I O VIs and functions Retrieving Front Panel Data Using a SubVI When you right click a subVI and select Enable Database Access from the shortcut menu a yellow box appears around the subVI as shown in Figure 13 8 LabVIEW reference time u16 for additional msecs Figure 13 8 Retrieving Logged Data The yellow box that looks like a filing cabinet includes terminals for accessing data from the datalog file When you enable database access for the subVI the inputs and outputs of the subVI actually act as outputs returning their logged data record indicates the record to retrieve National Instruments Corporation 13 17 LabVIEW User Manual Chapter 13 File 1 0 LabVIEW User Manual invalid record indicates whether the record number exists timestamp is the time the record was created and front panel data is a cluster of the front panel objects You can access the data of a front panel object by wiring the front panel data cluster to the Unbundle function You also can retrieve values for specific inputs and outputs by
179. erial ports and DAQ devices can run concurrently with other operations if Sequence structures do not prevent them from doing so Sequence structures also hide sections of the block diagram and interrupt the natural left to right flow of data When you need to control the execution order consider establishing data dependency between the nodes For example you can use error I O to control the execution order of I O Refer to the Error Handling section of Chapter 6 Running and Debugging VIs for more information about error I O Also do not use Sequence structures if you want to update an indicator from different frames of the Sequence structure For example a VI used in a test application might have a Status indicator that displays the name of the current test in progress If each test is a subVI called from a different frame you cannot update the indicator from each frame as shown by the broken wire in the following block diagram Because all frames of a Sequence structure execute before any data pass out of the structure only one frame can assign a value to the Status indicator Instead use a Case structure and a While Loop as shown in the following example 8 10 ni com Chapter 8 Loop and Case Structures Running Test 1 Each case in the Case structure is equivalent to a Sequence structure frame Each iteration of the While Loop executes the next case The Status indicator displays the status of t
180. erics and so on Some accept only one dimensional arrays although the array elements can be of any type Some functions accept all types of data including complex numerics Refer to Appendix B Polymorphic Functions for more information about polymorphic functions Handling Variant Data LabVIEW User Manual Variant data do not conform to a specific data type and they contain attributes such as channel names and channel units Lab VIEW represents variant data with the variant data type The variant data type differs from other data types because it includes the control or indicator name the data type information and the data itself Use the Variant functions located on the Functions Advanced Data Manipulation Variant palette to create and manipulate variant data You can convert any LabVIEW data type to the variant data type to use variant data in other VIs and functions For example if you convert a string to variant data the variant data type stores the text and indicates that the text is a string Use the variant data type when it is important to manipulate data independently of data type You also can represent data independently of type without using the variant data type by flattening the data into strings For example the Get All Control Values method returns information about the controls and indicators from a VI as an array of clusters Each cluster in the array contains the data type and value of each control or indica
181. ertically or horizontally or to maintain the current proportions of the object press the lt Shift gt key as you click the object and drag it To resize an object around its center point press lt Ctrl Shift gt and click the resizing cursors Macintosh Press the lt Option Shift gt keys Sun Press the lt Meta Shift gt keys Linux Press the lt Alt Shift gt keys Scaling Front Panel Objects You can set the front panel objects to scale or automatically resize in relation to the window size when you resize the front panel window You can set one object on the front panel to scale or you can set all objects on the front panel to scale However you cannot set multiple objects to scale on the front panel unless you set all of them to scale or unless you group the objects first To scale an object select the object and select Edit Scale Object With Panel National Instruments Corporation 4 5 LabVIEW User Manual Chapter 4 Building the Front Panel LabVIEW User Manual If you set a single front panel object to scale the object resizes itself automatically in relation to any change in the front panel window size The other objects on the front panel reposition themselves to remain consistent with their previous placement on the front panel but do not scale to fit the new window size of the front panel Immediately after you designate a single object on the front panel to scale automatically gray lines outline several regions
182. erver OPON Sorio e sie Gate nies EEA E E ERER 17 9 Creating HTML Documents ni anneni e e n 17 9 Publishing Front Panel Images 000 00 eee ee eeeeseeeeeeseeseeeseeeeeaecneeeaesseeeaeesees 17 10 Front Panel Image Formats eee eeceeeeeseeseceeeeseseeeeseeseeeseeaeees 17 10 Viewing and Controlling Front Panels Remotely 00 0 cece ees ceeeseeeeeeeeseeeeeeees 17 10 Configuring the Server for Clients ect eceeceeseeseeseeneceseeseeesesseeneeeseeeaees 17 11 Remote Panel License norm secs sie saesseg es se cevte sig eves sus E EES RE 17 11 Viewing and Controlling Front Panels in LabVIEW or from a Web BLOWSER ick snctecesetesdHvesus cot abst Seets fh beeans SoeuybsuensdesSedtech sea 17 12 Viewing and Controlling Front Panels in LabVIEW 17 12 Viewing and Controlling Front Panels from a Web Browser 17 12 Functionality Not Supported in Viewing and Controlling Remote Front Panels nennir aee a E E EE EEEE bans 17 13 Low Level Communications Applications sesseesseeesssresrerssesresrsresrsrrsresesresrsresresesees 17 14 TEP and WD Picci ret E E e e T E EE EEO AETI ES 17 14 DDE Windows aan anra e a E E E A ee 17 15 Apple Events and PPC Toolbox Macintosh sseessssesseeesssesreersersrsererrsrseese 17 15 Pipe VIS UNIX er e aes A aie 17 15 Executing System Level Commands Windows and UNIX eee 17 15 LabVIEW User Manual xiv ni com Contents Chapter 18 ActiveX ActiveX Objects Properties Methods and Event
183. es such as dynamic link libraries DLLs to manipulate LabVIEW data for use in other applications to create and manipulate Windows registry keys and to call a section of code from text based programming languages Refer to the Using External Code in LabVIEW manual for more information about using the Advanced functions Adding Terminals to Block Diagram Functions You can change the number of terminals for some functions For example to build an array with 10 elements you must add 10 terminals You can add terminals to expandable functions by using the Positioning tool to drag the corner of the function You also can use the Positioning tool to remove terminals from expandable functions but you cannot remove a terminal that is already wired You must first delete the existing wire to remove the terminal You also can add or remove terminals by right clicking one of the terminals on the icon and selecting Add Input Add Output Remove Input or Remove Output from the shortcut menu Depending on the function you can add terminals for inputs outputs or refnum controls The Add Input and Add Output shortcut menu items add a terminal immediately after the terminal you right clicked The Remove Input and Remove Output shortcut menu items remove the terminal you right clicked If you use the shortcut menu items to remove a wired terminal LabVIEW removes the terminal and disconnects the wire National Instruments Corporation 5 9 LabVIEW U
184. es as part of the control name Also include measurement units if applicable in the control name For example if a control sets the high limit temperature and has a default value of 75 F name the control high limit temperature 75 degF If you will use the subVI on multiple platforms avoid using special characters in control names For example use degF instead of F Name Boolean controls so users can determine what the control does in the TRUE state Use names like Cancel Reset and Initialize that describe the action taken Viewing the Hierarchy of Vis The Hierarchy Window displays a graphical representation of the calling hierarchy for all VIs in memory including type definitions and global variables Select Browse Show VI Hierarchy to display the Hierarchy Window Use this window to view the subVIs and other nodes that make up the current VI As you move the Operating tool over objects in the Hierarchy Window LabVIEW displays the name of each VI You can use the Positioning tool to drag a VI from the Hierarchy Window to the block diagram to use the VI as a subVI in another VI You also can select and copy a node or several nodes to the clipboard and paste them on other block diagrams Double click a VI in the Hierarchy Window to display the front panel of that VI A VI that contains subVIs has an arrow button on its border Click this arrow button to show or hide subVIs A red arrow button appears when all subVIs are hidden
185. et Read returns variant data which you must manipulate with the Variant to Data function located on the Functions DataSocket Variant palette In some cases you must convert variant data to LabVIEW data DataSocket and Variant Data In some cases the VI or other application that programmatically reads the data cannot convert the data back into its original data type such as when you subscribe to data from another application Also you might want to add an attribute to the data such as a timestamp or warning which the data types do not permit In these cases use the To Variant function located on the Functions DataSocket Variant palette to programmatically convert the data you write to a DataSocket connection to variant data Figure 17 3 shows a block diagram that continually acquires a temperature reading converts the data to variant data and adds a timestamp as an attribute to the data National Instruments Corporation 17 7 LabVIEW User Manual Chapter 17 Networking in LabVIEW dstp localhost temp DataSocket Write et Variant Attribute Figure 17 3 Converting Live Temperature Data to Variant Data When another VI reads the live data the VI must convert the variant data to a data type it can manipulate Figure 17 4 shows a block diagram that continually reads temperature data from a DataSocket connection converts the variant data into a temperature reading retrieves the timestamp attribute associated with each
186. et connections with controls and indicators include the following e Publish a value from a front panel control to manipulate a control and publish the data for other users to subscribe to through a control or indicator For example if you place a knob on your front panel that raises or lowers temperature a user on another computer can subscribe to the data and use it in a control wired to a subVI or function or view the data in an indicator A user cannot manipulate a front panel control on his or her VI while the control subscribes to data from the DataSocket connection e Publish a value that appears in a front panel indicator so another user can subscribe to the data and view the data in an control or indicator on his or her front panel or use the results as data in a control wired to an input in a subVI or function For example a VI that calculates the mean temperature and displays the temperature in a thermometer on the front panel can publish the temperature data e Subscribe to a value from a front panel indicator to view data in a front panel indicator on your VI that appears in a control or indicator on the front panel of another VI e Subscribe to a value from a front panel control to view data in a front panel control on your VI that appears in a control or indicator on the front panel of another VI If you subscribe to the data with a control you can use the data in your VI by wiring the control to an input of a subVI or funct
187. ette panel window picture picture indicator pixel pixmap plot National Instruments Corporation G 11 Glossary Program execution element Nodes are analogous to statements operators functions and subroutines in text based programming languages On a block diagram nodes include functions structures and subVIs Front panel objects to manipulate and display numeric data Generic term for any item on the front panel or block diagram including controls indicators nodes wires and imported pictures Tool to access a shortcut menu for an object Object Linking and Embedding Having one dimension as in the case of an array that has only one row of elements Tool to enter data into controls operate them Display of icons that represent possible options VI window that contains the front panel the toolbar and the icon and connector panes Series of graphics instructions that a picture indicator uses to create a picture General purpose indicator for displaying pictures that can contain lines circles text and other types of graphic shapes Smallest unit of a digitized picture Standard format for storing pictures in which a color value represents each pixel A bitmap is a black and white version of a pixmap Graphical representation of an array of data shown either on a graph or a chart LabVIEW User Manual Glossary point polymorphism Positioning tool PPC probe Probe tool pr
188. ex shared libraries 7 12 distributing VIs 7 12 stand alone applications 7 12 distributing VIs 7 12 subVIs 7 4 VI Server applications 16 2 VIs 7 1 buttons controlling with keyboard shortcuts 4 3 front panel 4 10 byte stream files 13 3 C C code calling from LabVIEW 19 1 calculating equations 20 1 Call By Reference Node 16 7 Call Library Function Node 19 1 callback 8 12 callers chain of 6 6 displaying 6 6 calling code from text based programming languages 19 1 calling VIs dynamically 16 7 canceling existing errors See the LabVIEW Help captions 4 16 creating See the LabVIEW Help subVI tip strips See the LabVIEW Help Case structures 8 6 data types 8 7 error handling 6 10 selector terminals 8 7 values 8 7 specifying a default case 8 7 using See the LabVIEW Help chain of callers displaying 6 6 LabVIEW User Manual Index changing palette views See the LabVIEW Help character formatting 4 17 charts 11 1 adding plots See the LabVIEW Help anti aliased line plots 11 2 clearing See the LabVIEW Help creating See the LabVIEW Help customizing appearance 11 3 customizing behavior 11 6 history length 11 6 intensity 11 11 options 11 13 multiple scales 11 2 options 11 2 overlaid plots 11 6 remote front panels 17 13 scrolling 11 3 stacked plots 11 6 types 11 1 waveform 11 10 zooming See the LabVIEW Help checking available disk space See the LabVIEW Help CIN 19
189. f distance such as kilometers as shown in Figure 5 5 speed Boo m s distance 0 00 s time Joo Figure 5 6 Wiring Objects with Incompatible Units Results in Broken Wires To view the error move the Wiring tool over the broken wire until a tip appears or right click the broken wire and select List Errors from the shortcut menu The Error list window lists the following error You have connected numeric data types that have incompatible units Some VIs and functions are ambiguous with respect to units You cannot use these VIs and functions with other terminals that have units For example the Increment function is ambiguous with respect to units If you use distance units the Increment function cannot tell whether to add one meter one kilometer or one foot Because of this ambiguity you cannot use the Increment function and other functions that increment or decrement values with data that have associated units To avoid ambiguity in this example use a numeric constant with the proper unit and the Add function to create your own increment unit function as shown in Figure 5 7 distance 1 Figure 5 7 Creating an Increment Function with Units National Instruments Corporation 5 19 LabVIEW User Manual Chapter 5 Building the Block Diagram Block Diagram Data Flow LabVIEW follows a dataflow model for running VIs A block diagram node executes when all its inputs are available When a
190. f ring controls can have scroll bars Enumerated Type Controls Use enumerated type controls to give users a list of actions from which to select An enumerated type control or enum is similar to a ring control of strings However with an enumerated type control the value is a string instead of a number as with ring controls For example you can use an enumerated type control to select the cases of a Case structure Refer to the Case Structures section of Chapter 8 Loop and Case Structures for more information about Case structures The enumerated type control data type is unsigned byte unsigned word or unsigned long Right click the enumerated type control and select Representation from the shortcut menu to change the data type of the control Advanced Enumerated Type Controls and Indicators All arithmetic functions except Increment and Decrement treat the enumerated type control the same as an unsigned numeric Increment increments the last enumerated value to the first and Decrement decrements the first enumerated value to the last When coercing a signed National Instruments Corporation 4 13 LabVIEW User Manual Chapter 4 Building the Front Panel integer to an enumerated type negative numbers are changed to equal the first enumerated value and out of range positive numbers are changed to equal the last enumerated value Out of range unsigned integers are always changed to equal the last enumerated value If you co
191. fault Set a terminal setting to required only if the VI must have the input or output to run properly In the Context Help window required connections are bold recommended connections are plain text and optional connections are dimmed if you have the Detailed view selected or do not appear if you have the Simple view selected National Instruments Corporation 7 7 LabVIEW User Manual Chapter 7 Creating Vis and SubVIs Creating an Icon Every VI displays an icon shown at left in the upper right corner of the front panel and block diagram windows An icon is a graphical representation of a VI It can contain text images or a combination of both If you use a VI as a subVI the icon identifies the subVI on the block diagram of the VI The default icon contains a number that indicates how many new VIs you have opened since launching LabVIEW Create custom icons to replace the default icon by right clicking the icon in the upper right corner of the front panel or block diagram and selecting Edit Icon from the shortcut menu or by double clicking the icon in the upper right corner of the front panel You also can drag a graphic from anywhere in your file system and drop it in the upper right corner of the front panel or block diagram LabVIEW converts the graphic to a 32 x 32 pixel icon Depending on the type of monitor you use you can design a separate icon for monochrome 16 color and 256 color mode LabVIEW uses the monochrome ico
192. fer to the Creating Your Own Help Files section of this chapter for more information about using HTML and RTF files to create help files Refer to Chapter 16 Programmatically Controlling VIs for more information about creating HTML and RTF files programmatically When you save documentation to an RTF file specify if you want to create a file suitable for online help files or for word processing In the help file format LabVIEW saves the graphics to external bitmap files In the word processing file format LabVIEW embeds the graphics in the document For HTML files LabVIEW saves all graphics externally in the JPEG or PNG formats National Instruments Corporation 14 3 LabVIEW User Manual Chapter 14 Documenting and Printing Vis LabVIEW User Manual Selecting Graphic Formats for HTML Files When you save documentation to an HTML file you can select the format of the graphics files and the color depth The JPEG format compresses graphics well but can lose some graphic detail This format works best for photos For line art front panels and block diagrams JPEG compression can result in fuzzy graphics and uneven colors JPEG graphics are always 24 bit graphics If you select a lower color depth black and white for example graphics save with the depth you requested but the result is still a 24 bit graphic The PNG format also compresses graphics well although not always as well as the JPEG format However PNG compression does not
193. file format is similar to other ini files It begins with a LabVIEW section marker followed by the option name and the values such as of fscreenUpdates True If you want to use a different options file specify the file in the shortcut you use to start LabVIEW For example to use an options file on your computer named lvrc instead of labview ini right click the LabVIEW icon on the desktop and select Properties Click the Shortcut tab and type labview pref lvrc in the Target text box Macintosh LabVIEW stores options in the LabVIEW Preferences text file in the System Preferences folder 3 6 ni com Chapter 3 LabVIEW Environment If you want to use a different options file copy the LabVIEW Preferences file to the LabVIEW folder and make options changes in the Options dialog box When you launch LabVIEW it first looks for an options file in the Lab VIEW folder If it does not find the file there it looks in the System folder If it does not find the file there it creates a new one in the System folder LabVIEW writes all changes you make in the Options dialog box to the first LabVIEW Preferences file it finds UNIX LabVIEW stores options in the labviewrc file in your home directory If you change an option in the Options dialog box LabVIEW writes the change to the labviewrc file You can create a labviewrc file in the program directory to store options that are the same for all users such as the VI search path Use the l
194. functions located on the Functions File I O Advanced File Functions palette to control each file I O operation individually Use the principal low level functions to create or open a file write data to or read data from the file and close the file Use the other low level functions to perform the following tasks e Create directories e Move copy or delete files e List directory contents e Change file characteristics e Manipulate paths A path shown at left is a LabVIEW data type that identifies the location of a file on disk The path describes the volume that contains the file the directories between the top level of the file system and the file and the name of the file Enter or display a path using the standard syntax for a given platform with the path control or indicator Refer to the Path Controls and Indicators section of Chapter 4 Building the Front Panel for more information about path controls and indicators Figure 13 2 shows how to use low level VIs and functions to send numbers to a Microsoft Excel spreadsheet file When you run this VI the Open Create Replace VI opens the numbers x1s file The Write File function writes the string of numbers to the file The Close function closes the file If you do not close the file the file stays in memory and is not accessible from other applications or to other users 13 6 ni com Chapter 13 File 1 0 4C Windows Desktop numbers xls Open Create
195. g point value undefined data 6 7 infinite While Loops 8 3 ini files reading and writing 13 12 inserting elements in arrays See the LabVIEW Help objects in palettes See the LabVIEW Help LabVIEW User Manual Index objects on block diagram See the LabVIEW Help installers building 7 12 instances of subVIs determining 6 6 suspending execution 6 5 instrument drivers E 1 LabVIEW See the LabVIEW Help instrument library adding VIs and controls 3 4 instruments configuring 1 3 controlling 7 2 integers converting B 1 overflow and underflow 6 7 intensity charts 11 11 color mapping 11 12 options 11 13 intensity graphs 11 11 color mapping 11 12 options 11 13 Internet See Web invalid paths 4 11 Invoke Node 16 4 ActiveX 18 2 iteration terminals For Loops 8 2 While Loops 8 3 IVI instrument drivers See the LabVIEW Help passing logical names 4 14 J Joint Photographic Experts Group files 12 6 JPEG files 12 6 14 4 Web Server 17 10 LabVIEW User Manual K keyboard shortcuts 4 3 controlling buttons 4 3 setting navigation order 4 4 knobs See also numerics adding color ramps 4 9 front panel 4 8 knowledge bases E 1 L labeling 4 16 captions 4 16 constants 5 4 creating free labels See the LabVIEW Help editing See the LabVIEW Help fonts 4 17 global variables 10 3 local variables 10 2 resizing See the LabVIEW Help units of measure 5 17 labels displaying aut
196. gs Numeric data and string data differ because string data are ASCII characters and numeric data are not Text and spreadsheet files accept strings only To write numeric data to a text or spreadsheet file you must first convert the numeric data to a string To add a set of numerics to an existing string convert the numeric data to a string and use the Concatenate Strings or another String function to add the new string to the existing string Use the String Number Conversion functions located on the Functions String String Number Conversion palette to convert numerics to strings A string can include a set of numerics you display in a graph or chart For example you can read a text file that includes a set of numerics that you want to plot to a chart However those numerics are in ASCII text so you must read the numerics as a string and then format the string into a set of numerics before you plot the numerics to a chart Figure 9 2 shows a string that includes a set of numerics converts the string to numerics builds an array of numerics and plots the numerics to a graph ormat String HE EEE KEE Figure 9 2 Converting a String to Numerics Converting Data Types to XML Extensible Markup Language XML is a formatting standard that uses tags to describe data Unlike an HTML tag an XML tag does not tell a browser how to format a piece of data Instead an XML tag identifies a piece of data For example
197. h the Technical Support section of ni com NI Developer Zone The NI Developer Zone at ni com zone is the essential resource for building measurement and automation systems At the NI Developer Zone you can easily access the latest example programs system configurators tutorials technical news as well as a community of developers ready to share their own techniques Customer Education National Instruments provides a number of alternatives to satisfy your training needs from self paced tutorials videos and interactive CDs to instructor led hands on courses at locations around the world Visit the Customer Education section of ni com for online course schedules syllabi training centers and class registration System Integration If you have time constraints limited in house technical resources or other dilemmas you may prefer to employ consulting or system integration services You can rely on the expertise available through our worldwide network of Alliance Program members To find out more about our Alliance system integration solutions visit the System Integration section of ni com National Instruments Corporation E 1 LabVIEW User Manual Appendix E Technical Support Resources Worldwide Support National Instruments has offices located around the world to help address your support needs You can access our branch office Web sites from the Worldwide Offices section of ni com Branch office Web sites pro
198. handled event types is available Debugging technique that animates VI execution to illustrate the data flow in the VI Voltage pulse from an external source that triggers an event such as A D conversion First in first out memory buffer The first data stored is the first data sent to the acceptor See refnum Type of signal conditioning that allows you to filter unwanted signals from the signal you are trying to measure Data of any type that has been converted to a string usually for writing the data to a file Iterative loop structure that executes its subdiagram a set number of times Equivalent to text based code For i 0 to n 1 do Node that executes equations you enter as text Especially useful for lengthy equations too cumbersome to build in block diagram form Subdiagram of a Sequence structure Label on the front panel or block diagram that does not belong to any other object LabVIEW User Manual Glossary front panel function Functions palette G General Purpose Interface Bus global variable glyph GPIB graph graph control group H handle LabVIEW User Manual Interactive user interface of a VI Front panel appearance imitates physical instruments such as oscilloscopes and multimeters Built in execution element comparable to an operator function or statement in a text based programming language Palette that contains VIs functions block diagram structures and
199. he LabVIEW Help subpalettes See the LabVIEW Help wires See the LabVIEW Help multicolumn listboxes See listbox controls LabVIEW User Manual 1 18 multiple threads running See the LabVIEW Help naming controls 7 9 VIs 7 11 NaN not a number floating point value undefined data 6 7 National Instruments Alliance Program E 1 customer education E 1 Developer Zone E 1 system integration services E 1 technical support E 1 worldwide offices E 2 native file dialog boxes See the LabVIEW Help navigation order setting 4 4 needles adding 4 8 networking See communication NI Developer Zone E 1 NI DAQ Configuration Utility 1 4 nodes 2 4 block diagram 5 5 Call By Reference 16 7 execution flow 5 20 HiQ script node 20 5 Invoke 16 4 MATLAB script node 20 5 Property 16 3 resizing See the LabVIEW Help normal conditions as errors See the LabVIEW Help not a number NaN floating point value undefined data 6 7 Not a Path 4 11 ni com Index notification of errors See the LabVIEW Help front panel and block diagram National Instruments Corporation numbers terminals 5 1 overflow and underflow 6 7 grouping and locking on front panel 4 5 numerics hidden on front panel See the LabVIEW changing representation See the Help LabVIEW Help hiding on front panel comparing C 2 controls and indicators 4 8 using See the LabVIEW Help converting B 1 data types table 5 2 equations 20 1
200. he VI You can run a VI if the Run button on the toolbar appears as a solid white arrow shown at left The solid white arrow also indicates you can use the VI as a subVI if you create a connector pane for the VI A VI runs when you click the Run or Run Continuously buttons or the single stepping buttons on the block diagram toolbar Clicking the Run button runs the VI once The VI stops when the VI completes its data flow Clicking the Run Continuously button runs the VI continuously until you stop it manually Clicking the single stepping buttons runs the VI in incremental steps Refer to the Single Stepping section of this chapter for more information about using the single stepping buttons to debug a VI 3 Note Avoid using the Abort Execution button to stop a VI Either let the VI complete its data flow or design a method to stop the VI programmatically By doing so the VI is at a known state For example place a button on the front panel that stops the VI when you click the button Configuring How a VI Runs Select File VI Properties and select Execution from the Category pull down menu to configure how a VI runs For example you can configure a VI to run immediately when it opens or to pause when called as a subVI You also can configure the VI to run at different priorities For National Instruments Corporation 6 1 LabVIEW User Manual Chapter 6 Running and Debugging VIs example if it is crucial that a VI runs without waiting
201. he VI for each case The Status indicator is updated in the case before the one that calls the corresponding subVI because data pass out of the structure after each case executes Unlike a Sequence structure a Case structure can pass data to end the While Loop during any case For example if an error occurs while running the first test the Case structure can pass FALSE to the conditional terminal to end the loop However a Sequence structure must execute all its frames even if an error occurs Event Driven Programming LabVIEW is a dataflow programming environment where the flow of data determines the execution order of block diagram elements With events in LabVIEW the user s direct interaction with objects on the front panel and the order of the block diagram elements can determine the flow of data ay Note Event driven programming is available only in the LabVIEW Full and Professional Development Systems What Are Events Events are caused by actions the user performs For example clicking the mouse generates a mouse event pressing a key on the keyboard generates a keyboard event and so on In an event driven program the program first waits for events to occur responds to those events then returns to waiting for the next event How the program responds depends on the code written for that specific event The order in which an event driven program executes depends on which events occur and on the order in which those events
202. he block diagram select Functions Array Array Constant to place the array shell on the front panel then place a string constant numeric constant or cluster constant in the array shell You can use an array constant as a basis for comparison with another array Array Index Display A 2D array contains rows and columns As shown in Figure 9 8 the upper display of the two boxes on the left is the row index and the lower display is the column index The combined display to the right of the row and National Instruments Corporation 9 11 LabVIEW User Manual Chapter 9 Grouping Data Using Strings Arrays and Clusters LabVIEW User Manual column displays shows the value at the specified position Figure 9 8 shows that the value at row 6 column 13 is 66 1 Row 2 Column 3 Value at row column Figure 9 8 Array Control Rows and columns are zero based meaning the first column is column 0 the second column is column 1 and so on Changing the index display for the following array to row 1 column 2 displays a value of 6 0 2 3 4 6 7 8 10 11 If you try to display a column or row that is out of the range of the array dimensions the array control is dimmed to indicate that there is no value defined and LabVIEW displays the default value of the data type The default value of the data type depends on the data type of the array Use the Positioning tool to show more than one row or colum
203. he examples general controls custom 11b for examples of controls with imported graphics Grouping and Locking Objects Use the Positioning tool to select the front panel objects you want to group and lock together Click the Reorder button on the toolbar and select Group or Lock from the pull down menu Grouped objects maintain their relative arrangement and size when you use the Positioning tool to move and resize them Locked objects maintain their location on the front panel and you cannot delete them until you unlock them You can set objects to be grouped and locked at the same time Tools other than the Positioning tool work normally with grouped or locked objects Resizing Objects You can change the size of most front panel objects When you move the Positioning tool over a resizable object resizing handles appear at the corners of a rectangular object and resizing circles appear on a circular object When you resize an object the font size remains the same Resizing a group of objects resizes all the objects within the group Some objects change size only horizontally or vertically when you resize them such as digital numeric controls and indicators Others keep the same proportions when you resize them such as knobs The Positioning cursor appears the same but the dashed border that surrounds the object moves in only one direction You can manually restrict the growth direction when you resize an object To restrict the growth v
204. he high level VIs perform read or write operations in addition to opening and closing the file Avoid placing the high level VIs in loops because the VIs perform open and close operations each time they run Refer to the Disk Streaming section for more information about keeping files open while you perform multiple operations The high level VIs expect a file path input If you do not wire a file path a dialog box appears for you to specify a file to read from or write to If an error occurs the high level VIs display a dialog box that describes the error You can choose to halt execution or to continue Figure 13 1 shows how to use the high level Write To Spreadsheet File VI to send numbers to a Microsoft Excel spreadsheet file When you run this VI LabVIEW prompts you to write the data to an existing file or to create a new file IN Write To Spreadsheet File vi Figure 13 1 Using a High Level VI to Write to a Spreadsheet Use the Binary File VIs located on the Functions File I O Binary File VIs palette to read from and write to files in binary format Data can be integers or single precision floating point numerics National Instruments Corporation 13 5 LabVIEW User Manual Chapter 13 File 1 0 Using Low Level and Advanced File 1 0 Vis and Functions LabVIEW User Manual Use low level File I O VIs and functions located on the middle row of the Functions File I O palette and the Advanced File I O
205. he indicator terminals where they exit the block diagram reenter the front panel and appear in front panel indicators Block Diagram Objects Objects on the block diagram include terminals nodes and functions You build block diagrams by connecting the objects with wires Block Diagram Terminals Block diagram terminals represent the data type of the front panel control or indicator For example a DBL terminal shown at left represents a double precision floating point numeric control or indicator National Instruments Corporation 5 1 LabVIEW User Manual Chapter 5 Building the Block Diagram A terminal is any point to which you can attach a wire other than to another wire LabVIEW has control and indicator terminals node terminals constants and specialized terminals on structures such as the input and output terminals on the Formula Node You use wires to connect terminals and pass data to other terminals Right click a block diagram object and select Visible Items Terminals from the shortcut menu to view the terminals Right click the object and select Visible Items Terminals again to hide the terminals This shortcut menu item is not available for expandable functions Control and Indicator Data Types Table 5 1 shows the symbols for the different types of control and indicator terminals The color and symbol of each terminal indicate the data type of the control or indicator Control terminals have a thicker bor
206. he keyboard enters a carriage return Refer to the Strings on the Front Panel section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about the string control and indicator Path Controls and Indicators Use path controls and indicators to enter or return the location of a file or directory Path controls and indicators work similarly to string controls and indicators but LabVIEW formats the path using the standard syntax for the platform you are using 4 10 ni com Chapter 4 Building the Front Panel Invalid Paths If a function that returns a path fails the function returns an invalid path value Not a Path in the indicator Use the Not a Path value as the default value for a path control so you can detect when the user fails to provide a path and display a file dialog box with options for selecting a path Use the File Dialog function to display a file dialog box Empty Paths An empty path in a path control appears as an empty string on Windows and Macintosh and as a slash on UNIX Use empty paths to prompt the user to specify a path When you wire an empty path to a file input output I O function the empty path refers to the list of drives mapped to the computer Macintosh The empty path refers to the mounted volumes UNIX The empty path refers to the root directory Array and Cluster Controls and Indicators Use the array and cluster controls and indicators located on the C
207. he number of ports as shown in Figure 11 7 Binary Representations Figure 11 7 Using Bundle Function with Digital Graph ports specifies the number of data elements to treat as a single integer If you have 8 bit data represented as an 8 bit integer the number of ports is one Also if you have 32 bit data represented as a 32 bit integer the number of ports is one If you have three sources of 8 bit data you have 24 bits to represent as a single integer In this case use the Interleave function to interleave the 8 bit data and specify the number of ports as three as shown in Figure 11 8 11 14 ni com Chapter 11 Graphs and Charts Figure 11 8 Using Interleave Function with Digital Graph In Figure 11 8 enter 3 in Port to graph all three arrays of 8 bit data Enter 2 in Port to graph two arrays of 8 bit data Enter 5 in Port to graph five arrays of 8 bit data This results in 16 of the 40 bits containing no values Masking Data The VI in Figure 11 6 produces a graph in which each plot represents one bit in the data You also can select reorder and combine bits in the data before you display it on the graph Selecting reordering and combining bits is called masking the data Use a mask to combine the plots of two or more different bits and display them on a single plot If you have an array of 8 bit integers you can plot up to 8 bits on a single plot If you have an array of 16 bit integers y
208. he one shown at left in the upper right corner of the front panel and block diagram windows An icon is a graphical representation of a VI It can contain text images or a combination of both If you use a VI as a subVI the icon identifies the subVI on the block diagram of the VI You can double click on the icon to customize or edit it Refer to the Creating an Icon section of Chapter 7 Creating VIs and SubVIs for more information about icons You also need to build a connector pane shown at left to use the VI as a subVI The connector pane is a set of terminals that corresponds to the controls and indicators of that VI similar to the parameter list of a function call in text based programming languages The connector pane defines the 2 4 ni com Chapter 2 Introduction to Virtual Instruments inputs and outputs you can wire to the VI so you can use it as a subVI A connector pane receives data at its input terminals and passes the data to the block diagram code through the front panel controls and receives the results at its output terminals from the front panel indicators When you view the connector pane for the first time you see a connector pattern You can select a different pattern if you want The connector pane generally has one terminal for each control or indicator on the front panel You can assign up to 28 terminals to a connector pane If you anticipate changes to the VI that would require a new input or output leave extra
209. he screen You can change the way the Functions palette appears Refer to the Customizing the Controls and Functions Palettes section of this chapter for more information about customizing the Functions palette Navigating the Controls and Functions Palettes Tools Palette Use the navigation buttons on the Controls and Functions palettes to navigate and search for controls VIs and functions When you click a subpalette icon the entire palette changes to the subpalette you selected You also can right click a VI icon on the palette and select Open VI from the shortcut menu to open the VI The Controls and Functions palettes contain the following navigation buttons e Up Takes you up one level in the palette hierarchy e Search Changes the palette to search mode In search mode you can perform text based searches to locate controls VIs or functions in the palettes e Options Opens the Function Browser Options dialog box from which you can configure the appearance of the palettes a The Tools palette is available on the front panel and the block diagram A tool is a special operating mode of the mouse cursor The cursor corresponds to the icon of the tool selected in the palette Use the tools to operate and modify front panel and block diagram objects Select Window Show Tools Palette to display the Tools palette You can place the Tools palette anywhere on the screen Tip Press the lt Shift gt key and righ
210. hem rather than loading all subVIs when you open a VI e Create a plug in architecture for the application to add functionality to the application after you distribute it to customers For example you might have a set of data filtering VIs all of which take the same parameters By designing the application to dynamically load these VIs from a plug in directory you can ship the application with a partial set of these VIs and make more filtering options available to users by placing the new filtering VIs in the plug in directory Building VI Server Applications LabVIEW User Manual The programming model for VI Server applications is based on refnums Refnums also are used in file I O network connections and other objects in LabVIEW Refer to the References to Objects or Applications section Chapter 4 Building the Front Panel for more information about refnums Typically you open a refnum to an instance of LabVIEW or to a VI You then use the refnum as a parameter to other VIs The VIs get read or set write properties execute methods or dynamically load a referenced VI Finally you close the refnum which releases the referenced VI from memory Use the following functions and nodes located on the Functions Application Control palette to build VI Server applications e Open Application Reference Opens a refnum to the local or remote application you are accessing through the server or to access a remote instance of LabVIEW
211. hich functions to use with each data type National Instruments Corporation 5 3 LabVIEW User Manual Chapter 5 Building the Block Diagram LabVIEW User Manual Constants Constants are terminals on the block diagram that supply fixed data values to the block diagram Universal constants are constants with fixed values such as pi 7 and infinity cc User defined constants are constants you define and edit before you run a VI Label a constant by right clicking the constant and selecting Visible Items Label from the shortcut menu Universal constants have predetermined values for their labels that you can edit by using the Operating tool or the Labeling tool Most constants are located at the bottom or top of their palettes Universal Constants Use universal constants for mathematical computations and formatting strings or paths LabVIEW includes the following types of universal constants e Universal numeric constants A set of high precision and commonly used mathematical and physical values such as the natural logarithm base e and the speed of light The universal numeric constants are located on the Functions Numeric Additional Numeric Constants palette e Universal string constants A set of commonly used non displayable string characters such as line feed and carriage return The universal string constants are located on the Functions String palette e Universal file constants A set of commonly used file pa
212. how Context Help to display the Context Help window The VI or object description also appears in any VI documentation you generate Setting up the VI Revision History LabVIEW User Manual Use the History window in each VI to display the development history of the VI including revision numbers Record and track the changes you make to the VI in the History window as you make them Select Tools VI Revision History to display the History window You also can print the revision history Refer to the Printing Documentation section of this chapter for more information about printing the revision history Revision Numbers The revision number is an easy way to track changes to a VI The revision number starts at zero and increases incrementally every time you save the VI The current revision number stored on disk appears in the History window To display the current revision number in the titlebar of the VI select Tools Options select Revision History from the top pull down menu and place a checkmark in the Show revision number in titlebar checkbox The number LabVIEW displays in the titlebar of the History window and the titlebar of the VI is the next revision number which is the current revision number plus one When you add a comment to the history the header of the comment includes the next revision number The revision number does not increase when you save a VI if you change only the History window 14 2 ni com Chapter 14 Docum
213. i com Chapter 7 Creating Vis and SubVIs I subVlex1 vi Diagram 2 fe S Lm E kaa 132 Aceon Fo de Board ID You can create a subVI that performs that operation and call the subVI twice as shown in the following block diagram subVlex2 vi Diagram oll Sm elhea e izle l National Instruments Corporation 7 5 LabVIEW User Manual Chapter 7 Creating Vis and SubVIs You also can reuse the subVI in other VIs Refer to Chapter 8 Loop and Case Structures for more information about using loops to combine common operations Setting up the Connector Pane To use a VI as a subVI you need to build a connector pane shown at left The connector pane is a set of terminals that corresponds to the controls and indicators of that VI similar to the parameter list of a function call in text based programming languages The connector pane defines the inputs and outputs you can wire to the VI so you can use it as a subVI Refer to the Icon and Connector Pane section of Chapter 2 Introduction to Virtual Instruments for more information about connector panes Define connections by assigning a front panel control or indicator to each of the connector pane terminals To define a connector pane right click the icon in the upper right corner of the front panel window and select Show Connector from the shortcut menu The connector pane replaces the icon Each rectangle on the connector pane represents a terminal Use the
214. ication or VI Select a method by using the Operating tool to click the method terminal or by right clicking the white area of the node and selecting Methods from the shortcut menu The name of the method is always the first terminal in the list of parameters in the Invoke Node If the method returns a value the method terminal displays the return value Otherwise the method terminal has no value The Invoke Node lists the parameters from top to bottom with the name of the method at the top and the optional parameters in gray at the bottom LabVIEW User Manual 16 4 ni com Chapter 16 Programmatically Controlling Vis Manipulating Application Class Properties and Methods You can get or set properties on a local or remote instance of LabVIEW perform methods on LabVIEW or both Figure 16 1 shows how to display all VIs in memory on a local computer in a string array on the front panel Figure 16 1 Displaying All Vis in Memory on a Local Computer To find the VIs in memory on a remote computer wire a string control to the machine name input of the Open Application Reference function as shown in Figure 16 2 and enter the IP address or domain name You also must select the Exported VIs in Memory property because the All VIs in Memory property used in Figure 16 1 applies only to local instances of LabVIEW machine name Figure 16 2 Displaying All Vis in Memory on a Remote Computer Manipulating VI Class Prope
215. ics to and from a binary file National Instruments Corporation 13 9 LabVIEW User Manual Chapter 13 File 1 0 Creating Datalog Files You can create and read datalog files by enabling front panel datalogging or by using the low level or Advanced File functions located on the Functions File O Advanced File Functions palette to acquire data and write the data to a file Refer to the Logging Front Panel Data section of this chapter for more information about creating and accessing datalog files from the front panel You do not have to format the data in a datalog file However when you write or read datalog files you must specify the data type For example if you acquire a temperature reading with the time and date the temperature was recorded you write the data to a datalog file and specify the data as a cluster of one number and two strings Refer to the Simple Temp Datalogger VI in the examples file datalog 11b for an example of writing data to a datalog file If you read a file that includes a temperature reading with the time and date the temperature was recorded you specify that you want to read a cluster of one number and two strings Refer to the Simple Temp Datalog Reader VI in the examples file datalog 11b for an example of reading a datalog file Writing Waveforms to Files LabVIEW User Manual Use the Write Waveforms to File and Export Waveforms to Spreadsheet File VIs located on the Functions Waveform Wavef
216. ictly typed control refnums accept only control refnums of the same kind of data For example if the type of a strictly typed control refnum is a slide of 32 bit integers you can wire a slide of 32 bit integers a slide of 8 bit integers or a slide of double precision scalars to the control refnum terminal but not a slide of a cluster of 32 bit integers Control refnums you create from a control are strictly typed by default A red star in the lower left corner of the control refnum on the front panel indicates the control refnum is strictly typed On the block diagram strict appears on the Property Node or Invoke Node wired to the control refnum terminal to indicate that the control refnum is strictly typed 3 Note Because the latch mechanical actions are incompatible with strictly typed control refnums Boolean controls with latch mechanical action produce weakly typed control refnums Weakly typed control refnums are more flexible in the type of data they accept For example if the type of a weakly typed control refnum is slide you can wire a 32 bit integer slide single precision slide or a cluster of 32 bit integer slides to the control refnum terminal If the type of a weakly typed control refnum is control you can wire a control refnum of any type of control to the control refnum terminal 3 Note When you wire a Property Node to a weakly typed control refnum terminal the value produces variant data which might require conversio
217. ific ways The chapters in this section describe the usefulness of each LabVIEW feature and outline each class of VIs and functions Part II Building and Editing VIs contains the following chapters National Instruments Corporation Chapter 8 Loop and Case Structures describes how to use structures on the block diagram to repeat blocks of code and to execute code conditionally or in a specific order Chapter 9 Grouping Data Using Strings Arrays and Clusters describes how to use strings arrays and clusters to group data Chapter 10 Local and Global Variables describes how to use local and global variables pass information between locations in your application that you cannot connect with a wire Chapter 11 Graphs and Charts describes how to use graphs and charts to display plots of data in a graphical form Chapter 12 Graphics and Sound VIs describes how to display or modify graphics and sound in VIs Chapter 13 File I O describes how to perform file I O operations Chapter 14 Documenting and Printing VIs describes how to document and print VIs Chapter 15 Customizing VIs describes how to configure VIs and subVIs to work according to your application needs Chapter 16 Programmatically Controlling VIs describes how to communicate with VIs and other instances of LabVIEW so you can programmatically control VIs and LabVIEW Il 1 LabVIEW User Manual Part II Building and Editing Vis e Chapter 17 Networ
218. ile Loops 6 8 underflow of numbers 6 7 undo options 3 6 ungrouping front panel objects 4 5 unit labels 5 17 universal constants 5 4 unlocking front panel objects 4 5 VIs See the LabVIEW Help updating palettes See the LabVIEW Help upgrading VIs 7 11 URLs for DataSocket 17 3 User Datagram Protocol 17 14 user interface See front panel user library adding VIs and controls 3 4 user defined colors See the LabVIEW Help user defined constants 5 4 user defined error codes See the LabVIEW Help V variables global 10 2 creating 10 2 initializing 10 4 memory 10 5 race conditions 10 4 read and write 10 3 using carefully 10 4 ni com Index local 10 1 strictly typed VI refnums 16 7 creating 10 2 VI object 16 3 initializing 10 4 viewing memory 10 5 See also displaying race conditions 10 4 views 3 5 read and write 10 3 changing See the LabVIEW Help using carefully 10 4 creating 3 5 variant data 5 16 deleting See the LabVIEW Help ActiveX 18 2 editing 3 5 controls and indicators sharing See the LabVIEW Help data type table 5 3 virtual instruments See VIs converting to 5 16 VIs 2 1 DataSocket 17 7 adding to libraries 3 4 editing attributes See the LabVIEW Help broken 6 2 flattened data and 5 17 building 7 1 handling 5 16 calling dynamically 16 7 versions calling remotely 16 1 comparing 7 2 comparing versions 7 2 reverting to last saved See the LabVIEW configuring appea
219. iles When to Use Binary Files A binary file uses a fixed number of storage bytes on disk For example storing any number from 0 to 4 billion in binary format such as 1 1 000 or 1 000 000 takes up 4 bytes for each number Use binary files to save numeric data and to access specific numbers from a file or randomly access numbers from a file Binary files are machine readable only unlike text files which are human readable Binary files are the most compact and fastest format for storing data You can use multiple data types in binary files but it is uncommon Binary files are more efficient because they use less disk space and because you do not need to convert data to and from a text representation when you store and retrieve data A binary file can represent 256 values in byte of disk space Often binary files contain a byte for byte image of the data as it was stored in memory except for cases like extended and complex numerics When the file contains a byte for byte image of the data as it was stored in memory reading the file is faster because conversion is not necessary Refer to the LabVIEW Data Storage Application Note for more information about how LabVIEW stores data 3 Note Text and binary files are both known as byte stream files which means they store data as a sequence of characters or bytes National Instruments Corporation 13 3 LabVIEW User Manual Chapter 13 File 1 0 Refer to the Read Binary File and Write
220. in LabVIEW and examples of using the ActiveX Events VIs ActiveX Vis Functions Controls and Indicators Use the following VIs functions controls and indicators to access the objects properties methods and events associated with other ActiveX enabled applications LabVIEW User Manual Use the automation refnum control located on the Controls ActiveX palette to create a reference to an ActiveX object Right click this control on the front panel to select an object from the type library you want to access Use the Automation Open function located on the Functions Communication ActiveX palette to open an ActiveX object Use the ActiveX container located on the Controls ActiveX palette to access and display an ActiveX object on the front panel Right click this control to select the object you want to access Use the Property Node located on the Functions Communication ActiveX palette to get read and set write the properties associated with an ActiveX object Use the Invoke Node located on the Functions Communication ActiveX palette to invoke the methods associated with an ActiveX object Use the ActiveX Events VIs located on the Functions Communication ActiveX ActiveX Events palette to manage the events that occur to an ActiveX object you placed in the ActiveX container on the front panel Use the ActiveX variant control and indicator located on the Controls ActiveX palette to pass data to or from subVIs
221. indexing loops 8 4 comparing C 2 constants 9 11 controls and indicators 4 11 data type table 5 3 LabVIEW User Manual Index converting clusters to and from See the LabVIEW Help creating 9 11 default data 6 8 deleting elements See the LabVIEW Help dimensions 9 8 examples 9 8 1D arrays 9 8 2D arrays 9 10 functions 5 7 global variables 10 5 indexes 9 8 display 9 11 inserting elements See the LabVIEW Help moving See the LabVIEW Help polymorphism B 5 replacing elements See the LabVIEW Help resizing See the LabVIEW Help restrictions 9 11 size of 6 8 artificial data dependency 5 20 assigning passwords to block diagrams 7 12 auto constant labels displaying See the LabVIEW Help auto indexing 8 4 For Loops 8 4 unexpected data 6 7 While Loops 8 5 automatic wiring 5 11 automation custom interfaces 18 6 refnum control 18 2 background color of front panel objects See the LabVIEW Help LabVIEW User Manual l 2 binary creating files 13 9 file I O 13 3 floating point arithmetic 6 7 bitmap files 12 6 blink speed See the LabVIEW Help block diagram 2 2 adding space without resizing 5 22 aligning objects See the LabVIEW Help coercion dots 5 12 commenting out sections 6 6 constants 5 4 controlling source code 7 2 copying objects See the LabVIEW Help creating controls and indicators See the LabVIEW Help data flow 5 20 data types table 5 2 DataSocket 17 6 dele
222. indicators appear in the records of datalog files you create when you log the front panel data Refer to the Logging Front Panel Data section of Chapter 13 File I O for more information about logging data To prevent users from accessing a control by pressing the lt Tab gt key while running the VI place a checkmark in the Skip this control when tabbing checkbox in the Key Navigation dialog box You can change the color of many objects but not all of them For example block diagram terminals of front panel objects and wires use specific colors for the type and representation of data they carry so you cannot change them Use the Coloring tool and right click an object or workspace to add or change the color of front panel objects or the front panel and block diagram workspaces You also can change the default colors for most objects by selecting Tools Options and selecting Colors from the top pull down menu Using Imported Graphics LabVIEW User Manual You can import graphics from other applications to use as front panel backgrounds items in ring controls and parts of other controls and indicators Refer to the LabVIEW Custom Controls Indicators and Type Definitions Application Note for more information about using graphics in controls To import a graphic copy it to the clipboard and paste it on the front panel You also can select Edit Import Picture from File 4 4 ni com Chapter 4 Building the Front Panel Refer to t
223. ine the paths to each of these VIs you must access a VI Class property The number of VIs in memory determines the number of times the For Loop executes Place the Open VI Reference and Close LV Object Reference functions inside the For Loop because you need a VI refnum for each VI in memory Do not close the Application refnum until the For Loop finishes retrieving all the VI paths Open Application Reference ERI p Application pi App Alls gt Figure 16 4 Using Application and VI Class Properties and Methods LabVIEW User Manual 16 6 ni com Chapter 16 Programmatically Controlling VIs Dynamically Loading and Calling Vis You can dynamically load VIs instead of using statically linked subVI calls A statically linked subVI is one you place directly on the block diagram of a caller VI It loads at the same time the caller VI loads Unlike statically linked subVIs dynamically loaded subVIs do not load until the caller VI makes the call to the subVI If you have a large caller VI you can save load time and memory by dynamically loading the subVI because the subVI does not load until the caller VI needs it and you can release it from memory after the operation completes Call By Reference Nodes and Strictly Typed VI Refnums Use the Call By Reference Node to dynamically call VIs The Call By Reference Node requires a strictly typed VI refnum The strictly typed VI refnum identifies the connector pane
224. ion National Instruments Corporation 17 5 LabVIEW User Manual Chapter 17 Networking in LabVIEW e Publish from and subscribe to a front panel control so users can manipulate a control on the front panel of your VI from the front panels of their VIs When you run the VI the front panel control on your VI retrieves the current value that another VI or application published through the DataSocket connection When a user changes the control value on his or her front panel the DataSocket connection publishes the new value to the front panel control of your VI If you then manipulate the value of your front panel control your VI publishes the value to the front panels of other users The front panel objects that subscribe to data do not have to be the same kind of objects that publish the data However the front panel objects must be the same data type or if they are numeric data they must coerce For example you can use a digital indicator in your VI to view the data a thermometer in another VI generates The thermometer can be a floating point number and the digital indicator can be an integer Front panel DataSocket connections are primarily intended for sharing live data To read data in local files FTP servers or Web servers use the DataSocket Read function located on the Functions Communication DataSocket palette the File I O VIs and functions located on the Functions File I O palette or the Application Control VIs and fu
225. ion about using structures Use the following structures located on the Functions Structures palette to control how a block diagram executes processes e For Loop Executes a subdiagram a set number of times e While Loop Executes a subdiagram until a condition is met e Case structure Contains multiple subdiagrams only one of which executes depending on the input value passed to the structure e Sequence structure Contains one or more subdiagrams which execute in sequential order e Formula Node Performs mathematical operations based on numeric input Refer to the Formula Nodes section of Chapter 20 Formulas and Equations for information about using Formula Nodes e Event Structure Contains one or more subdiagrams that execute depending on how the user interacts with the VI Right click the border of the structure to display the shortcut menu National Instruments Corporation 8 1 LabVIEW User Manual Chapter 8 Loop and Case Structures For Loop and While Loop Structures For Loops N While Loops His LabVIEW User Manual Use the For Loop and the While Loop to control repetitive operations A For Loop shown at left executes a subdiagram a set number of times The value in the count terminal an input terminal shown at left indicates how many times to repeat the subdiagram Set the count explicitly by wiring a value from outside the loop to the left or top side of the count terminal or se
226. ion contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire ood accident actions of third parties or other events outside reasonable control Copyright Under the copyright laws this publication may not be reproduced or transmitted in any form electronic or mechani
227. is format works best for photos For line art front panels and block diagrams JPEG compression can result in fuzzy graphics and uneven colors The PNG format also compresses graphics well although not always as well as the JPEG format However PNG compression does not lose any detail Viewing and Controlling Front Panels Remotely You can view and control a VI front panel remotely either from within LabVIEW or from within a Web browser by connecting to the LabVIEW built in Web Server When you open a front panel remotely from a client the Web Server sends the front panel to the client but the block diagram and all the subVIs remain on the server computer You can interact with the front panel in the same way as if the VI were running on the client except the block diagram executes on the server Use this feature to publish entire front panels or to control your remote applications safely easily and quickly B Note Use the LabVIEW Web Server if you want to control entire VIs Use the DataSocket server to read and write data on a single front panel control in a VI Refer to the Using DataSocket Technology section of this chapter for more information about using the DataSocket Server LabVIEW User Manual 17 10 ni com Chapter 17 Networking in LabVIEW Configuring the Server for Clients The user at the server computer must first configure the server before a client can view and control a front panel remotely using LabVIEW or a Web
228. ity graph the new data replace old data The intensity graph can have cursors like other graphs Each cursor displays the x y and z values for a specified point on the graph Digital Graphs Use the waveform graph to display digital data especially when you work with timing diagrams or logic analyzers Refer to Chapter 8 Digital I O of the LabVIEW Measurements Manual for more information about acquiring digital data The waveform graph in Figure 11 6 displays an array of six 8 bit unsigned integers The graph represents the integers in binary format and each bit represents a plot on the graph National Instruments Corporation 11 13 LabVIEW User Manual Chapter 11 Graphs and Charts ale Numbers Binary Representations Bit 1 1 Bit 2 1010 Bit 3 110111 Bit 4 1011001 D Bit5 1100101 Bit 6 F1 Bit Digital Graph aq Bit 0 i i i ii f LabVIEW User Manual Figure 11 6 Graphing Integers Digitally The Binary Representations column in Figure 11 6 corresponds to the first plot Bit 0 on the digital graph The Number column corresponds to the second plot Bit 1 and so on For example the number 89 requires seven bits of memory The binary graphical representation of the number 89 appears on point 3 on the graph To build a VI that displays digital data use the Bundle function to assemble the trigger time X0 Ax dX the array of numbers and t
229. king in LabVIEW describes how to use VIs to communicate or network with other processes including those that run on other applications or on remote computers e Chapter 18 ActiveX describes how to provide a public set of objects commands and functions that other Windows applications can access e Chapter 19 Calling Code from Text Based Programming Languages describes how to call code from text based programming languages and use DLLs e Chapter 20 Formulas and Equations describes how to use equations in VIs LabVIEW User Manual Il 2 ni com Loop and Case Structures Structures are graphical representations of the loops and case statements of text based programming languages Use structures on the block diagram to repeat blocks of code and to execute code conditionally or in a specific order Like other nodes structures have terminals that connect them to other block diagram nodes execute automatically when input data are available and supply data to output wires when execution completes Each structure has a distinctive resizable border to enclose the section of the block diagram that executes according to the rules of the structure The section of the block diagram inside the structure border is called a subdiagram The terminals that feed data into and out of structures are called tunnels A tunnel is a connection point on a structure border For more information Refer to the LabVIEW Help for more informat
230. kpoint tool 6 5 commenting out sections of a block diagram 6 6 error handling 6 8 execution highlighting 6 4 Probe tool 6 4 single stepping 6 4 suspending execution 6 5 tools disabling 6 6 undefined data 6 7 LabVIEW User Manual l 8 decimal point localized See the LabVIEW Help default cases 8 7 default data arrays 6 8 While Loops 6 8 defining error codes See the LabVIEW Help user colors See the LabVIEW Help deleting array elements See the LabVIEW Help broken wires 5 12 datalog records 13 16 objects on front panel or block diagram See the LabVIEW Help palette views See the LabVIEW Help structures See the LabVIEW Help designing block diagram 5 22 dialog boxes 4 19 front panel 4 18 projects 7 1 subVIs 7 8 Developer Zone E 1 developing VIs 7 1 guidelines 1 2 tracking development See documenting VIs development resources E 1 diagnostic resources E 1 dialog boxes controls 4 15 using See the LabVIEW Help designing 4 19 font 4 17 native file See the LabVIEW Help remote front panels 17 13 ring controls 4 13 dialog functions 5 8 ni com dials See also numerics adding color ramps 4 9 front panel 4 8 digital controls and indicators 4 9 digital graphs 11 13 anti aliased line plots 11 2 masking data 11 15 D 1 dimensions arrays 9 8 directories converting libraries to See the LabVIEW Help converting to libraries See the LabVIEW Help directory paths See path
231. ks e Create an HTML document e Embed static or animated images of the front panel in an HTML document Currently only Netscape browsers support animated images e Embed a VI that clients can view and control remotely e Add text above and below the embedded VI front panel image e Place a border around an image or embedded VI e Preview the document e Save the document to disk e Enable the Web Server for publishing HTML documents and front panel images on the Web National Instruments Corporation 17 9 LabVIEW User Manual Chapter 17 Networking in LabVIEW Publishing Front Panel Images Use a snap URL in a Web browser or an HTML document to return a static image of the front panel of a VI currently in memory The query parameters in the URL specify the VI name and the attributes of the image For example use http web server address snap VIName vi where VIName vi is the name of the VI you want to view Use a monitor URL to return an animated image of the front panel of a VI currently in memory The query parameters in the URL specify the VI name attributes of the animation and attributes of the image For example use http web server address monitor VIName vi where VIName vi is the name of the VI you want to view Front Panel Image Formats The Web Server can generate images of front panels in the JPEG and PNG image formats The JPEG format compresses graphics well but can lose some graphic detail Th
232. l Adding Space to Front Panel without Resizing Window You can add space to the front panel without resizing the window To increase the space between crowded or tightly grouped objects press the lt Ctrl gt key and use the Positioning tool to click the front panel workspace While holding the key combination drag out a region the size you want to insert Macintosh Press the lt Option gt key Sun Press the lt Meta gt key Linux Press the lt Alt gt key A rectangle marked by a dashed border defines where space will be inserted Release the key combination to add the space Front Panel Controls and Indicators Use the front panel controls and indicators located on the Controls palette to build the front panel Controls are knobs push buttons dials and other input devices Indicators are graphs LEDs and other displays Controls simulate instrument input devices and supply data to the block diagram of the VI Indicators simulate instrument output devices and display data the block diagram acquires or generates 3D and Classic Controls and Indicators Many front panel objects have a high color three dimensional appearance Set your monitor to display at least 16 bit color for optimal appearance of the objects The 3D front panel objects also have corresponding low color two dimensional objects Use the 2D controls and indicators located on the Controls Classic Controls palette to create VIs for 256 color and 16 col
233. l graphs gengraph 11b for an example of a graph that accepts this data type A multiplot waveform graph also accepts a cluster of an x value a Ax value and a 2D array of y data The graph interprets the y data as points on the graph and increments the x index by Ax starting at x 0 This data type is useful for displaying multiple signals all sampled at the same regular rate Refer to the Xo dX Y Multi Plot 3 graph in the Waveform Graph VI in the examples general graphs gengraph 11b for an example of a graph that accepts this data type A multiplot waveform graph accepts a plot array where the array contains clusters Each cluster contains a point array that contains the y data The inner array describes the points in a plot and the outer array has one cluster for each plot Figure 11 4 shows this array of the y cluster 11 8 ni com Chapter 11 Graphs and Charts array of cluster of y Figure 11 4 Array of Cluster y Use a multiplot waveform graph instead of a 2D array if the number of elements in each plot is different For example when you sample data from several channels using different time amounts from each channel use this data structure instead of a 2D array because each row of a 2D array must have the same number of elements The number of elements in the interior arrays of an array of clusters can vary Refer to the Y Multi Plot 2 graph in the Waveform Graph VI in the examples general graphs gengraph 11b for
234. le Loop that contains a Boolean value that determines if the VI performs another iteration Refers to Measurement amp Automation Explorer on Windows and to the NI DAQ Configuration Utility on Macintosh Part of the VI or function node that contains input and output terminals Data pass to and from the node through a connector Region in the upper right corner of a front panel or block diagram window that displays the VI terminal pattern It defines the inputs and outputs you can wire to a VI See universal constant and user defined constant Special window in LabVIEW that displays the names and locations of the terminals for a VI or function the description of controls and indicators the values of universal constants and descriptions and data types of control attributes Front panel object for entering data to a VI interactively or to a subVI programmatically such as a knob push button or dial Programming system in which the sequential order of instructions determines execution order Most text based programming languages are control flow languages Palette that contains front panel controls indicators and decorative objects Changing the type of a data element G 4 ni com count terminal current VI curve in 3D DAQ DAQ Channel Wizard data acquisition data dependency data flow datalog file datalogging data type DDE National Instruments Corporation G 5 Glossary Terminal of a For L
235. les Use the Scan From File function to scan text in a file for string numeric path and Boolean values and then convert the text into a data type Often you can use this function instead of reading data from a file with the Read File function or Read Characters From File VI and scanning the resulting string with the Scan From String function Use the Scan From File function to read formatted text in the file Use the Seek function to set the mark where the scanning starts Creating Binary Files To create a binary file acquire a set of numbers and write them to a file You do not have to format the numbers unless you want to use the high level Binary File I O VIs located on the Functions File I O Binary File VIs palette Use the Write To 116 and Write To SGL VIs to save 1D and 2D arrays of numbers to a file You must first format the numbers as 16 bit integers or single precision floating point numerics Use the Read I16 and Read SGL VIs to read the files you created To write numbers of different data types such as double precision floating point numerics or 32 bit unsigned integers use the low level or Advanced File functions located on the Functions File I O Advanced File Functions palette When you read the file use the Read File function and specify the data type of the number Refer to the Read Binary File and Write Binary File VIs in the examples file smplfile 11b for examples of writing and reading floating point numer
236. ling Debugging Tools LabVIEW User Manual You can disable the debugging tools to reduce memory requirements and to increase performance slightly Right click the connector pane and select VI Properties Select Execution in the Category pull down menu and remove the checkmark from the Allow Debugging checkbox 6 6 ni com Chapter 6 Running and Debugging Vis Undefined or Unexpected Data Undefined data which are NaN not a number or Inf infinity invalidate all subsequent operations Floating point operations return the following two symbolic values that indicate faulty computations or meaningless results NaN not a number represents a floating point value that invalid operations produce such as taking the square root of a negative number e Inf infinity represents a floating point value that operations produce such as dividing a number by zero LabVIEW does not check for overflow or underflow conditions on integer values Overflow and underflow for floating point numbers is in accordance with IEEE 754 Standard for Binary Floating Point Arithmetic Floating point operations propagate NaN and Inf faithfully When you explicitly or implicitly convert NaN or Inf to integers or Boolean values the values become meaningless For example dividing 1 by zero produces Inf Converting Inf to a 16 bit integer produces the value 32 767 which appears to be a normal value Refer to the Numeric Conversion section of Appendix B
237. ll LabVIEW platforms When you run the VI on a different platform the dialog controls adapt their color and appearance to match the standard dialog box controls for that platform Select File VI Properties and select Window Appearance from the Category pull down menu to hide the menu bar and scroll bars and to create VIs that look and behave like standard dialog boxes for each platform Refer to the Configuring the Appearance and Behavior of VIs section of Chapter 15 Customizing VIs for more information about configuring the appearance and behavior of VIs Captions LabVIEW User Manual Use labels to identify objects on the front panel and block diagram LabVIEW includes two kinds of labels owned labels and free labels Owned labels belong to and move with a particular object and annotate that object only You can move an owned label independently but when you move the object that owns the label the label moves with the object You can hide owned labels but you cannot copy or delete them independently of their owners You also can display a unit label for numeric controls by selecting Visible Items Unit Label from the shortcut menu Refer to the Numeric Units and Strict Type Checking section of Chapter 5 Building the Block Diagram for more information about numeric units Free labels are not attached to any object and you can create move rotate or delete them independently Use them to annotate front panels and block diagra
238. ll its subdiagrams in sequential order A Case structure shown at left has two or more subdiagrams or cases Only one subdiagram is visible at a time and the structure executes only one case at a time An input value determines which subdiagram executes The Case structure is similar to case statements or if then else statements in text based programming languages The case selector label at the top of the Case structure shown at left contains the name of the selector value that corresponds to the case in the center and decrement and increment arrows on each side Click the 8 6 ni com Chapter 8 Loop and Case Structures decrement and increment arrows to scroll through the available cases You also can click the down arrow next to the case name and select a case from the pull down menu A Wire an input value or selector to the selector terminal shown at left to determine which case executes You must wire an integer Boolean value string or enumerated type value to the selector terminal You can position the selector terminal anywhere on the left border of the Case structure If the type of selector terminal is Boolean the structure has a TRUE case and a FALSE case If the selector terminal is an integer string or enumerated type value the structure can have arbitrarily many cases Specify a default case for the Case structure to handle out of range values Otherwise you must explicitly list every possible input value Fo
239. ll rights reserved Important Information Warranty The media on which you receive National Instruments software are warranted not to fail to execute programming instructions due to defects in materials and workmanship for a period of 90 days from date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace software media that do not execute programming instructions if National Instruments receives notice of such defects during the warranty period National Instruments does not warrant that the operation of the software shall be uninterrupted or error free A Return Material Authorization RMA number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this document is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the informat
240. lly 18 5 viewing 18 4 Property Node 16 3 ActiveX 18 5 finding objects or terminals See the LabVIEW Help modifying listbox items 4 12 protocols DataSocket 17 3 low level communication 17 14 publishing VIs on Web 17 9 pull down menus on front panel 4 13 purging datalog records 13 16 Q queues variant data 5 17 R race conditions 10 4 read globals 10 3 read locals 10 3 reading from files 13 1 records 13 15 deleting 13 16 specifying while retrieving front panel data using subVIs 13 18 refnums automation 18 2 Call By Reference Node 16 7 control 16 8 controls and indicators 4 15 data type table 5 3 using See the LabVIEW Help file I O 13 1 strictly typed 16 7 LabVIEW User Manual Index remotely calling VIs 16 1 removing broken wires 5 12 objects on front panel or block diagram See the LabVIEW Help structures See the LabVIEW Help subVIs from polymorphic VIs See the LabVIEW Help terminals from functions 5 9 VIs from libraries See the LabVIEW Help reordering objects See the LabVIEW Help repeating blocks of code For Loops 8 2 While Loops 8 2 Repeat Until Loops See While Loops replacing elements in arrays See the LabVIEW Help objects on block diagram See the LabVIEW Help objects on front panel 4 2 text in strings See the LabVIEW Help reports generating error clusters See the LabVIEW Help printing 14 5 Report Generation VIs 14 5 resizing arrays See the
241. lp notify 8 13 example programs E 1 examples 1 3 arrays 9 8 1D arrays 9 8 2D arrays 9 10 exception control See the LabVIEW Help executable VIs debugging See the LabVIEW Help executing system level commands 17 15 execution flow 5 20 controlling with Sequence structures 8 9 ni com highlighting debugging VIs 6 4 displaying data bubbles See the LabVIEW Help probing automatically See the LabVIEW Help suspending debugging VIs 6 5 Expression Nodes 20 4 F FAQs E 1 FIFO variant data 5 17 file DataSocket protocol 17 3 file I O 13 1 advanced file functions 13 6 basic operation 13 1 binary files 13 3 creating 13 9 byte stream files 13 3 configuration file VIs format 13 13 purpose 13 13 reading and writing ini files 13 12 datalog files 13 4 creating 13 10 disk streaming 13 7 flow through parameters 13 12 formats 13 2 functions 5 8 high level VIs 13 5 logging front panel data 13 15 low level VIs and functions 13 6 networking and 17 1 paths 13 6 reading waveforms 13 11 refnums 13 1 National Instruments Corporation l 11 Index spreadsheet files creating 13 8 text files 13 2 creating 13 8 writing waveforms 13 10 file sharing 7 2 finding controls VIs and functions on the palettes 3 2 errors 6 2 objects text and VIs See the LabVIEW Help first in first out variant data 5 17 fixing VIs 6 2 debugging techniques 6 3 flattened data variant data and 5
242. m Boolean controls and indicators breakpoint Breakpoint tool broken Run button broken VI buffer byte stream file LabVIEW User Manual Ordered indexed list of data elements of the same type Condition in a dataflow programming language in which the arrival of data rather than its value triggers execution of a node American Standard Code for Information Interchange Capability of loop structures to disassemble and assemble arrays at their borders As an array enters a loop with auto indexing enabled the loop automatically disassembles it extracting scalars from ID arrays ID arrays extracted from 2D arrays and so on Loops assemble data into arrays as data exit the loop in the reverse order Ability of scales to adjust to the range of plotted values On graph scales autoscaling determines maximum and minimum scale values Pictorial description or representation of a program or algorithm The block diagram consists of executable icons called nodes and wires that carry data between the nodes The block diagram is the source code for the VI The block diagram resides in the block diagram window of the VI Front panel objects to manipulate and display Boolean TRUE or FALSE data Pause in execution used for debugging Tool to set a breakpoint on a VI node or wire Button that replaces the Run button when a VI cannot run because of errors VI that cannot or run because of errors signified by a broken arrow i
243. mat for information In LabVIEW acceptable data types for most VIs and functions are numeric array string Boolean path refnum enumeration waveform and cluster See dynamic data exchange LabVIEW User Manual Glossary default device directory discrete dithering DLL drag drive driver dynamic data exchange E empty array error in LabVIEW User Manual Preset value Many VI inputs use a default value if you do not specify a value Instrument or controller that is addressable as a single entity and controls or monitors real world I O points A device is often connected to the host computer through some type of communication network or can be a plug in device For data acquisition DAQ applications a DAQ device is inside your computer or attached directly to the parallel port of your computer Plug in boards PCMCIA cards and devices such as the DAQPad 1200 which connects to your computer s parallel port are all examples of DAQ devices SCXI modules are distinct from devices with the exception of the SCXI 1200 which is a hybrid Structure for organizing files into convenient groups A directory is like an address that shows the location of files A directory can contain files or subdirectories of files Having discontinuous values of the independent variable usually time Addition of Gaussian noise to an analog input signal By applying dithering and then averaging the input data you ca
244. ment arrows on each side Click the decrement and increment arrows to scroll through the available frames You also can click the down arrow 8 8 ni com Chapter 8 Loop and Case Structures next to the frame number and select a frame from the pull down menu Unlike the case selector label you cannot enter values in the frame label When you add delete or rearrange frames in a Sequence structure LabVIEW automatically adjusts the numbers in the frame labels A Sequence structure executes frame 0 then frame 1 then frame 2 until the last frame executes The Sequence structure does not complete execution or return any data until the last frame finishes M 0 0 2 Pl The sequence selector identifier at the top of the Sequence structure shown at left contains the current frame number and range of frames in the center and decrement and increment arrow buttons on each side For example in the sequence selector identifier shown at left 0 is the current frame number and 0 2 is the range of frames Click the decrement and increment arrow buttons to scroll through the available frames Use the Sequence structure to control the execution order when natural data dependency does not exist A node that receives data from another node depends on the other node for data and always executes after the other node completes execution Within each frame of a Sequence structure as in the rest of the block diagram data dependency determines the executio
245. ments must be of the same type You cannot use the Multiply function to do matrix multiplication If you use the Multiply function with two matrices LabVIEW takes the first number in the first row of the first matrix multiplies it by the first number in the first row of the second matrix and so on For operations involving a scalar and an array or cluster LabVIEW performs the function on the scalar and the respective elements of the structure For example LabVIEW can subtract a number from all elements of an array regardless of the dimensionality of the array For operations that involve a numeric type and an array of that type LabVIEW performs the function on each array element For example a graph is an array of points and a point is a cluster of two numeric types x and y To offset a graph by 5 units in the x direction and 8 units in the y direction you can add a point 5 8 to the graph National Instruments Corporation B 3 LabVIEW User Manual Appendix B Polymorphic Functions The following example shows the possible polymorphic combinations of the Add function Similar One Scalar Scalar Scalar gt scalar Scalar a Array Array Array Array array Scalar zi Cluster cluster an cluster Cluster uster Array of Array of Clusters Array of Clusters luster oo Polymorphism for Boolean Functions The logical functions take either Boolean or numeric input data If the input is numeric La
246. mming languages National Instruments Corporation 5 5 LabVIEW User Manual Chapter 5 Building the Block Diagram After you build a VI front panel and block diagram build the connector pane shown at left so you can use the VI as a subVI The connector pane is a set of terminals that corresponds to the controls and indicators of that VI similar to the parameter list of a function call in text based programming languages The connector pane defines the inputs and outputs you can wire to the VI so you can use it as a subVI Refer to the Setting up the Connector Pane section of Chapter 7 Creating VIs and SubVIs for more information about setting up connector panes Functions Overview Functions are the essential operating elements of LabVIEW Function icons on the Functions palette have pale yellow backgrounds and black foregrounds Functions do not have front panels or block diagrams but do have connector panes The Functions palette also includes the VIs that ship with LabVIEW Use these VIs as subVIs when you build data acquisition instrument control communication and other VIs Refer to the Using Built In VIs and Functions section of Chapter 7 Creating VIs and SubVIs for more information about using the built in VIs Numeric Functions Use the Numeric functions located on the Functions Numeric palette to create and perform arithmetic trigonometric logarithmic and complex mathematical operations on numbers and to conver
247. more information about the options available only on graphs or only on charts Waveform and XY graphs and charts have different options than intensity digital and 3D graphs and charts Refer to the Intensity Graphs and Charts 3D Graphs and Digital Graphs sections of this chapter for more information about intensity digital and 3D graph and chart options Multiple X and Y Scales on Graphs and Charts All graphs and charts support multiple x and y scales Use multiple scales on a graph or chart to display multiple plots that do not share a common x or y scale Right click the x or y scale of the waveform graph or chart and select Duplicate Scale from the shortcut menu to add multiple x or y scales to the graph or chart Anti Aliased Line Plots for Graphs and Charts You can improve the appearance of line plots in charts and graphs by using anti aliased lines When you enable anti aliased line drawing line plots appear smoother Anti aliased line drawing does not alter line widths line styles point styles and so on nye Note Anti aliased line drawing is not available on digital waveform graphs To enable anti aliased line plots right click the plot legend and select Anti aliased from the shortcut menu If the plot legend is not visible right click the chart or graph and select Visible Items Plot Legend from the shortcut menu 3 Note Because anti aliased line drawing can be computation intensive using anti aliased line plots
248. ms Use the Labeling tool to create free labels or to edit either type of label Front panel objects also can have captions Right click the object and select Visible Items Caption from the shortcut menu to display the caption Unlike a label a caption does not affect the name of the object and you can use it as a more descriptive object label The caption does not appear on the block diagram 4 16 ni com Chapter 4 Building the Front Panel Text Characteristics LabVIEW uses fonts already installed on your computer Use the Text Settings pull down menu on the toolbar to change the attributes of text If you select objects or text before you make a selection from the Text Settings pull down menu the changes apply to everything you select If you select nothing the changes apply to the default font Changing the default font does not change the font of existing labels It affects only those labels you create from that point on Select Font Dialog from the Text Settings pull down menu on the front panel to apply specific font styles to text you have selected If you do not select any text the Panel Default option contains a checkmark If you select Text Settings Font Dialog from the block diagram without selecting any objects the Diagram Default option contains a checkmark You can set different fonts for the front panel and for the block diagram For example you can have a small font on the block diagram and a large one on the fr
249. n about programmatically controlling VIs Capabilities of the VI Server Use the VI Server to perform the following programmatic operations National Instruments Corporation Call a VI remotely Configure an instance of LabVIEW to be a server that exports VIs you can call from other instances of LabVIEW on the Web For example if you have a data acquisition application that acquires and logs data at a remote site you can sample that data occasionally from your local computer By changing your LabVIEW preferences you can make some VIs accessible on the Web so that transferring the latest data is as easy as a subVI call The VI Server handles the networking details The VI Server also works across platforms so the client and the server can run on different platforms Edit the properties of a VI and LabVIEW For example you can dynamically determine the location of a VI window or scroll a front panel so that a part of it is visible You also can programmatically save any changes to disk Update the properties of multiple VIs rather than manually using the File VI Properties dialog box for each VI 16 1 LabVIEW User Manual Chapter 16 Programmatically Controlling Vis e Retrieve information about an instance of LabVIEW such as the version number and edition You also can retrieve environment information such as the platform on which LabVIEW is running e Dynamically load VIs into memory when another VI needs to call t
250. n at a time Array Functions Use the Array functions located on the Functions Array palette to create and manipulate arrays such as the following tasks e Extract individual data elements from an array e Insert delete or replace data elements in an array e Split arrays Automatically Resizing Array Functions The Index Array Replace Array Subset Insert Into Array Delete From Array and Array Subset functions automatically resize to match the dimensions of the input array you wire For example if you wire a 1D array to one of these functions the function shows a single index input If you 9 12 ni com Chapter 9 Grouping Data Using Strings Arrays and Clusters wire a 2D array to the same function it shows two index inputs one for the row and one for the column You can access more than one element or subarray row column or page with these functions by using the Positioning tool to manually resize the function When you expand one of these functions the functions expand in increments determined by the dimensions of the array wired to the function If you wire a 1D array to one of these functions the function expands by a single index input If you wire a 2D array to the same function the function expands by two index inputs one for the row and one for the column The index inputs you wire determine the shape of the subarray you want to access or modify For example if the input to an Index Array function is a
251. n before you can use the data The History Data property for charts is available only if the chart refnum is strictly typed Refer to the Handling Variant Data section of Chapter 5 Building the Block Diagram for more information about variant data National Instruments Corporation 16 9 LabVIEW User Manual Networking in LabVIEW VIs can communicate or network with other processes including those that run on other applications or on remote computers Use the networking features in LabVIEW to perform the following tasks e Share live data with other VIs running on a network using National Instruments DataSocket technology Publish front panel images and VI documentation on the Web Build VIs that communicate with other applications and VIs through low level protocols such as TCP UDP DDE Apple events and PPC Toolbox For more information Refer to the LabVIEW Help for more information about networking in LabVIEW Choosing among File 1 0 VI Server ActiveX and Networking Networking might not be the best solution for your application If you want to create a file that contains data other VIs and applications can read use the File I O VIs and functions Refer to Chapter 13 File I O for more information about using the File I O VIs and functions If you want to control other VIs use the VI Server Refer to Chapter 16 Programmatically Controlling VIs for more information about controlling VIs and other LabV
252. n effectively increase the resolution by another one half bit Dynamic Link Library To use the cursor on the screen to select move copy or delete objects Letter in the range a z followed by a colon to indicate a logical disk drive Software that controls a specific hardware device such as a DAQ device DDE Method to pass data between applications without user involvement or monitoring Array that has zero elements but has a defined data type For example an array that has a numeric control in its data display window but has no defined values for any element is an empty numeric array Error structure that enters a VI G 6 ni com error message error out error structure event Event Data Node execution highlighting external trigger F FIFO file refnum filtering flattened data For Loop Formula Node frame free label National Instruments Corporation G 7 Glossary Indication of a software or hardware malfunction or of an unacceptable data entry attempt The error structure that leaves a VI Consists of a Boolean status indicator a numeric code indicator and a string source indicator Condition or state of an analog or digital signal Node attached to the left and right sides of an Event structure indicating the available data for the event you configured that case to handle If you configure a single case to handle multiple events only the data that is common to all
253. n for printing unless you have a color printer Creating SubVls from Sections of a VI Designing SubVls LabVIEW User Manual Convert a section of a VI into a subVI by using the Positioning tool to select the section of the block diagram you want to reuse and selecting Edit Create SubVI An icon for the new subVI replaces the selected section of the block diagram LabVIEW creates controls and indicators for the new subVI and wires the subVI to the existing wires Creating a subVI from a selection is convenient but still requires careful planning to create a logical hierarchy of VIs Consider which objects to include in the selection and avoid changing the functionality of the resulting VI If users do not need to view the front panel of a subVI you can spend less time on its appearance including colors and fonts However front panel organization is still important because you might need to view the front panel while you debug the VI Place the controls and indicators as they appear in the connector pane Place the controls on the left of the front panel and the indicators on the right Place the error in clusters on the lower left of the front panel and 7 8 ni com Chapter 7 Creating Vis and SubVIs the error out clusters on the lower right Refer to the Setting up the Connector Pane section of this chapter for more information about setting up a connector pane If a control has a default value put the default value in parenthes
254. n order of nodes Refer to the Data Dependency and Artificial Data Dependency section of Chapter 5 Building the Block Diagram for more information about data dependency The tunnels of Sequence structures can have only one data source unlike Case structures The output can emit from any frame but data leave the Sequence structure only when all frames complete execution not when the individual frames complete execution As with Case structures data at input tunnels are available to all frames To pass data from one frame to any subsequent frame use a sequence local terminal shown at left An outward pointing arrow appears in the sequence local terminal of the frame that contains the data source The terminal in subsequent frames contains an inward pointing arrow indicating that the terminal is a data source for that frame You cannot use the sequence local terminal in frames that precede the first frame where you wired the sequence local Refer to the examples general structs 11b for examples of using Sequence structures National Instruments Corporation 8 9 LabVIEW User Manual Chapter 8 LabVIEW User Manual Loop and Case Structures Avoiding Overusing Sequence Structures To take advantage of the inherent parallelism in LabVIEW avoid overusing Sequence structures Sequence structures guarantee the order of execution and prohibit parallel operations For example asynchronous tasks that use I O devices such as PXI GPIB s
255. n the broken Run button Temporary storage for acquired or generated data File that stores data as a sequence of ASCII characters or bytes G 2 ni com C case Case structure channel channel name chart checkbox CIN cloning cluster Code Interface Node CIN National Instruments Corporation G 3 Glossary One subdiagram of a Case structure Conditional branching control structure that executes one of its subdiagrams based on the input to the Case structure It is the combination of the IF THEN ELSE and CASE statements in control flow languages Pin or wire lead to which you apply or from which you read the analog or digital signal Analog signals can be single ended or differential For digital signals you group channels to form ports Ports usually consist of either four or eight digital channels Unique name given to a channel configuration in the DAQ Channel Wizard 2D display of one or more plots in which the display retains previous data up to a maximum that you define The chart receives the data and updates the display point by point or array by array retaining a certain number of past points in a buffer for display purposes See also scope chart strip chart and sweep chart Small square box in a dialog box you can select or clear Checkboxes generally are associated with multiple options that you can set You can select more than one checkbox See Code Interface Node CIN To
256. n the format of the files You can read data from or write data to files in three formats text binary and datalog The format you use depends on the data you acquire or create and the applications that will access that data Use the following basic guidelines to determine which format to use e Ifyou want to make your data available to other applications such as Microsoft Excel use text files because they are the most common and the most portable e If you need to randomly access reads or writes or if speed and compact disk space are crucial use binary files because they are more efficient than text files in disk space and in speed e Ifyou want to manipulate complex records of data or different data types in LabVIEW use datalog files because they are the best way to store data if you intend to access the data only from LabVIEW and you need to store complex data structures When to Use Text Files LabVIEW User Manual Use text format files for your data to make it available to other users or applications if disk space and file I O speed are not crucial if you do not need to perform random access reads or writes and if numeric precision is not important Text files are the easiest format to use and to share Almost any computer can read from or write to a text file A variety of text based programs can read text based files Most instrument control applications use text strings Store data in text files when you want to access
257. nctions located on the Functions A pplication Control palette National Instruments recommends you publish only raw text and variant data for live front panel updates Reading and Writing Live Data through the Block Diagram LabVIEW User Manual From the block diagram you can programmatically read or write data using the DataSocket functions located on the Functions Communication DataSocket palette Use the DataSocket Write function to write live data through a DataSocket connection programmatically Figure 17 1 shows how to write a numeric value dstp localhost temp Figure 17 1 Publishing Data Using DataSocket Write 17 6 ni com Chapter 17 Networking in LabVIEW The DataSocket Write function is polymorphic so you can wire most data types to the data input Refer to the Polymorphic VIs and Functions section of Chapter 5 Building the Block Diagram for more information about polymorphic VIs and functions Use the DataSocket Read function to read live data from a DataSocket connection programmatically Figure 17 2 shows how to read data and convert it to a double precision floating point number DataSocket Read oe Figure 17 2 Reading a Single Value Using DataSocket Read dstp localhost temp hermometer Convert live data to a specific data type by wiring a control or constant to the type input of DataSocket Read If you do not specify a type the data output of DataSock
258. nd Methods ee eee 16 5 National Instruments Corporation xiii LabVIEW User Manual Contents Manipulating VI Class Properties and Methods eee eeeeseeseeeeeeeeeees 16 5 Manipulating Application and VI Class Properties and Methods 16 6 Dynamically Loading and Calling VIS eee eseeeeeeseeseeeseeaeeeseeseeeseeaseneeeaeeneeeaes 16 7 Call By Reference Nodes and Strictly Typed VI Refnums ee 16 7 Editing and Running VIs on Remote Compute 00 ce eeeeeeeseeseeeseeseeeseeseeeeeeseenees 16 8 Controlling Front Panel Objects eee ee eeeseeceeeeseceeceseeseeesecseeeaeceecsaeceseseseeseaeesees 16 8 Strictly Typed and Weakly Typed Control Refnums cccceceeeeseee ees 16 9 Chapter 17 Networking in LabVIEW Choosing among File I O VI Server ActiveX and Networking ss 17 1 LabVIEW as a Network Client and Server oo cece eceeeceseeseceseeseeseeeaeceeeeaeeneeeseeeees 17 2 Using DataSocket Technology ciiin a e e e pa Es 17 2 Specifying URD reren ra r E e R E E EET E I 17 3 Data Formats Supported by DataSocket sseeseeeesseesseereresresrsresresesresereesreee 17 4 Using DataSocket on the Front Panel sssesessssesseeesesrsesrsrsresrsresreresrssesreses 17 5 Reading and Writing Live Data through the Block Diagram 17 6 DataSocket and Variant Data eee eseeeeceeeseeeseeeeeeeeeseeeaees 17 7 Publishing VIs n the WeDi ciccvcsiececcsessckse oan in en EE R E EN Ei 17 9 WebS
259. ne that describes how to pass data to and from the subVI The connector pane does not make copies of data buffers from calling VIs Local variables make copies of data buffers When you read from a local variable you create a new buffer for the data from its associated control If you use local variables to transfer large amounts of data from one place on the block diagram to another you generally use more memory and consequently have slower execution speed than if you transfer data using a wire Memory Considerations when Using Global Variables When you read from a global variable LabVIEW creates a copy of the data stored in that global variable When you manipulate large arrays and strings the time and memory required to manipulate global variables can be considerable Manipulating global variables is especially inefficient when dealing with arrays because National Instruments Corporation 10 5 LabVIEW User Manual Chapter 10 Local and Global Variables if you modify only a single array element LabVIEW stores the entire array If you read from the global variable in several places in an application you create several memory buffers which is inefficient and slows performance LabVIEW User Manual 10 6 ni com Graphs and Charts Use graphs and charts to display plots of data in a graphical form Graphs and charts differ in the way they display and update data VIs with graphs usually collect the data in an array and th
260. neerses B 4 Polymorphism for Array FUnctions 00 0 0 cee eseeceesececeeeeeseeseceeeeseeseeesecseeeaecseenaeeeenaes B 5 Polymorphism for String Functions 000 0 eee eee ceceeseeeceteeeeeeeseeneeseeseeeaeeeseaeeneenaes B 5 Polymorphism for String Conversion Functions 2 0 0 0 cscs eeeeseeeeereeeees B 5 Polymorphism for Additional String to Number Functions B 5 Polymorphism for Cluster FUnctions cccceeseseecesseeeeeeceeecsecseeeaeeseesaeeseeaseasenaeeaes B 6 Polymorphism for Comparison FUunctions ecceeeccessceseeseseeeeeesseeseceeeeaseseeeseseeeaes B 6 Polymorphism for Log FUMCTtIONS ecceeseesecesceceneceeeesceeeeeececeaeeeaecseeseaeessaeeeaeersas B 7 Appendix C Comparison Functions Comparing Boolean Values iiie iee E E E N C 1 Co mp ring St Szat eie ca aceon araara eE L E EE e e E E EEE E EEA AE EA EASES S C 1 Comparing NUMELICS ws 205 sets despite hea eat en aia ha ee C 2 Comparing Arrays and Clusters ipress e E E E E AE s C 2 ARIE AY Soi cd cepted Ranh ewes inal E sed NbiNec betes E E pedve AET C 2 Compare Elements M d s p sirensis derre e C 2 Compare Aggregates Mode ssesessessseeresesirsrserersrsrsresrrsreresresrsees C 3 CVUSCCLS iosia Seeks Wet E e R A ER attest cab ERTER C 3 Compare Elements Mode 0 ce eceeceeeescceseesseeseceeeeseseeeeseeneeeaeeseees C 3 Compare Aggregates Mode eee ecescceseeseneeseeceseeseeeseeseeeaeesaees C 3 Appendix D Masking Digital Data Appendix
261. nent To create a range of gray colors create an array of 32 bit integers where the red green and blue values of each element are the same Graphics Formats VIs LabVIEW User Manual Use the Graphics Formats VIs located on the Functions Graphics amp Sound Graphics Formats palette to read data from and write data to several standard graphic file formats including bitmap bmp Portable Network Graphics png and Joint Photographic Experts Group jpg files You can use these VIs to perform the following tasks e Read data from a bitmap file for display in a picture indicator e Read data for image manipulation e Write an image for viewing in other applications Bitmap data are 2D arrays in which the data type of each point varies depending on the color depth For example in a black and white or 1 bit image each point is Boolean In 4 bit and 8 bit images each point is an index in a color table For 24 bit true color images each point is a mixture of red green and blue RGB values The VIs that read and write graphics files work with data in a simple flattened format that is closer to the way graphic files are written to disk with the data stored in a 1D array These graphics files are pixmaps which are similar in concept to bitmaps You can display this flattened data directly using the Draw Flattened Pixmap VI located on the Functions Graphics amp Sound Picture Functions palette This palette contains VIs
262. nformation This icon denotes a note which alerts you to important information This icon denotes a caution which advises you of precautions to take to avoid injury data loss or a system crash Bold text denotes items that you must select or click in the software such as menu items and dialog box options Bold text also denotes parameter names controls and buttons on the front panel dialog boxes sections of dialog boxes menu names and palette names Italic text denotes variables emphasis a cross reference or an introduction to a key concept This font also denotes text that is a placeholder for a word or value that you must supply Text in this font denotes text or characters that you should enter from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk drives paths directories programs subprograms subroutines device names functions operations variables filenames and extensions and code excerpts Bold text in this font denotes the messages and responses that the computer automatically prints to the screen This font also emphasizes lines of code that are different from the other examples Italic text in this font denotes text that is a placeholder for a word or value that you must supply xviii ni com About This Manual Platform Text in this font denotes a specific platform and indicates that the text following it applies only to that pla
263. ngs overriding defaults See the LabVIEW Help functions 5 6 adding terminals 5 9 advanced 5 9 application control 5 9 array 5 7 block diagram 5 6 Boolean 5 6 cluster 5 7 dialog 5 8 file I O 5 8 finding See the LabVIEW Help numeric 5 6 palette 3 1 customizing 3 4 navigating and searching 3 2 window titles See the LabVIEW Help polymorphic B 1 reference See the LabVIEW Help removing terminals 5 9 resizing See the LabVIEW Help string 5 7 time 5 8 waveform 5 8 l 13 Index G gauges See also numerics adding color ramps 4 9 front panel 4 8 generating reports 14 5 error clusters See the LabVIEW Help getting started 1 1 GIF files 14 4 global variables 10 2 creating 10 2 initializing 10 4 memory 10 5 race conditions 10 4 read and write 10 3 using carefully 10 4 GPIB configuring 1 3 graphics adding to VI icon See the LabVIEW Help creating colors 12 6 dragging and dropping See the LabVIEW Help drawing shapes 12 5 entering text 12 5 formats 12 6 for HTML files 14 4 graphs 12 3 importing 4 4 modifying colors 12 6 picture controls and indicators data type table 5 3 using 12 1 pixmaps 12 5 publishing front panels on Web 17 10 graphs 11 1 3D 11 15 adding plots See the LabVIEW Help anti aliased line plots 11 2 clearing See the LabVIEW Help LabVIEW User Manual Index creating See the LabVIEW Help cursors 11 4 adding See the LabVIEW H
264. nly a subset of the controls In these cases you can use a subVI that is set to print at completion Create a subVI and format the front panel the way you want LabVIEW to print it Instead of selecting Operate Print at Completion while in the VI select it while in the subVI When you want to print call the subVI and pass the data to it to print Additional Printing Techniques If standard LabVIEW printing methods do not meet your needs you can use the following additional techniques e Print data on a line by line basis If you have a line based printer connected to a serial port use the Serial Compatibility VIs to send text to the printer Doing so generally requires some knowledge of the command language of the printer e Export data to other applications such as Microsoft Excel save the data to a file and print from the other application e Windows and UNIX Use the System Exec VI e Macintosh Use the AESend Print Document VI e Windows Use ActiveX Automation to make another application print data Refer to Chapter 18 ActiveX for more information about ActiveX National Instruments Corporation 14 7 LabVIEW User Manual Customizing VIs You can configure VIs and subVIs to work according to your application needs For example if you plan to use a VI as a subVI that requires user input configure the VI so that its front panel appears each time you call it You can configure a VI in many ways either within the
265. nnect a floating point value to an enumerated type indicator the number is converted to the closest enumeration item which is one of the values in the enumerated type indicator LabVIEW handles out of range numbers as previously described If you connect an enumerated control to any numeric value the value is the enumerated type index To wire an enumerated type control to an enumerated type indicator the enumeration items must match The indicator can have additional items beyond the items in the control 1 0 Name Controls and Indicators LabVIEW User Manual Use the I O name controls and indicators located on the Controls I O or Controls Classic Controls I O palettes to pass DAQ channel names VISA resource names and IVI logical names you configure to I O VIs to communicate with an instrument or a DAQ device T O name constants are located on the Functions Instrument and Functions DAQ palettes Windows Use Measurement amp Automation Explorer available from the Tools menu to configure DAQ channel names VISA resource names and IVI logical names Macintosh Use the NI DAQ Configuration Utility available from the Tools menu to configure National Instruments DAQ hardware Use the DAQ Channel Wizard available from the Tools menu to configure DAQ channel names Macintosh and UNIX Use the configuration utilities for your instrument to configure VISA resource names and IVI logical names Refer to the documentation for you
266. nnector pane with getting a refnum to the selected VI You specify a particular VI using the vi path input on the Open VI Reference function Editing and Running Vis on Remote Computers An important aspect of both Application and VI refnums is their network transparency This means you can open refnums to objects on remote computers in the same way you open refnums to those objects on your computer After you open a refnum to a remote object you can treat it in exactly the same way as a local object with a few restrictions For operations on a remote object the VI Server sends the information about the operation across the network and sends the results back The application looks almost identical regardless of whether the operation is remote or local Controlling Front Panel Objects LabVIEW User Manual Use control refnums located on the Controls Refnum and Controls Classic Controls Refnum palettes to pass front panel object references to other VIs After you pass a control refnum to a subVI use Property Nodes and Invoke Nodes to read and write properties and invoke methods of the referenced front panel object Refer to the Case and Sequence Structures section of Chapter 8 Loop and Case Structures for information about using events to control block diagram behavior programmatically through front panel objects 16 8 ni com Chapter 16 Programmatically Controlling Vis Strictly Typed and Weakly Typed Control Refnums Str
267. nputs You can use default values and custom controls to decrease the complexity of the VIs Instead of creating your own cluster input copy a custom control from the Waveform and XY Plots VI in the examples picture demos 11b and place it on your front panel National Instruments Corporation 12 3 LabVIEW User Manual Chapter 12 Graphics and Sound VIs The Plot XY VI and the Plot Multi XY VI are similar to the Plot Waveform VI You use different controls to specify the cosmetic appearance of the plot because the XY plotting VIs have three plot styles two scatter plot styles and a plot style where a line is drawn at each unique x position to mark the minimum and maximum y values for that x value Using the Smith Plot Vis as SubVIs LabVIEW User Manual Use the Smith Plot VIs to study transmission line behavior such as in the telecommunications industry A transmission line is a medium through which you transmit energy and signals A transmission line can be a wire or it can be the atmosphere through which a signal transmits Transmission lines have an effect on the signal that is transmitting This effect called the impedance of the transmission line can attenuate or phase shift an AC signal The impedance of the transmission line is a measure of the resistance and the reactance of the line The impedance z is commonly listed as a complex number of the form z r jx where both resistance r and reactance x are components
268. nsists of Boolean values in the same data structure as the input The function Empty String Path accepts a path a scalar string clusters of strings arrays of strings and so on The output consists of Boolean values in the same data structure as the input You can use the Equal Not Equal Not A Number Path Refnum Empty String Path and Select functions with paths and refnums but no other Comparison functions accept paths or refnums as inputs B 6 ni com Appendix B Polymorphic Functions Comparison functions that use arrays and clusters normally produce Boolean arrays and clusters of the same structure You can right click the function and select Compare Aggregates in which case the function outputs a single Boolean value The function compares aggregates by comparing the first set of elements to produce the output unless the first elements are equal in which case the function compares the second set of elements and so on Polymorphism for Log Functions The Logarithmic functions take numeric input data If the input is an integer the output is a double precision floating point number Otherwise the output has the same numeric representation as the input These functions work on numbers arrays of numbers clusters of numbers arrays of clusters of numbers complex numbers and so on A formal and recursive definition of the allowable input type is as follows Numeric type numeric scalar OR array numeric type OR
269. nstances of LabVIEW When you get arefnum to a VI you load the VI into memory After you get the refnum the VI stays in memory until you close the refnum If you have multiple refnums to an open VI at the same time the VI stays in memory until you close all refnums to the VI With a refnum to a VI you can update all the properties of the VI available in the File VI Properties dialog box as well as dynamic properties such as front panel window position You also can programmatically print the VI save it to another location and export and import its strings to translate into another language Manipulating Application and VI Settings Use the VI Server to get and set application and VI settings by using the Property and Invoke Nodes You can get and set many application and VI settings only through the Property and Invoke Nodes Refer to examples viserver for examples of using the Application and VI Class properties and methods Property Nodes Use the Property Node to get and set various properties on an application or VI Select properties from the node by using the Operating tool to click the property terminal or by right clicking the white area of the node and selecting Properties from the shortcut menu National Instruments Corporation 16 3 LabVIEW User Manual Chapter 16 Programmatically Controlling Vis You can read or write multiple properties using a single node Use the Positioning tool to resize the Property Node to
270. nstruments Corporation 11 7 LabVIEW User Manual Chapter 11 Graphs and Charts a varying timebase Both graphs can display plots containing any number of points Both types of graphs accept several data types which minimizes the extent to which you must manipulate data before you display it Single Plot Waveform Graph Data Types The waveform graph accepts two data types for single plot waveform graphs The graph accepts a single array of values and interprets the data as points on the graph and increments the x index by one starting at x 0 The graph also accepts a cluster of an initial x value a Ax and an array of y data Refer to the Waveform Graph VI in the examples general graphs gengraph 11b for examples of the data types that single plot waveform graphs accept Multiplot Waveform Graph LabVIEW User Manual A multiplot waveform graph accepts a 2D array of values where each row of the array is a single plot The graph interprets the data as points on the graph and increments the x index by one starting at x 0 Wire a 2D array data type to the graph right click the graph and select Transpose Array from the shortcut menu to handle each column of the array as a plot This is particularly useful when you sample multiple channels from a DAQ device because the device returns the data as 2D arrays with each channel stored as a separate column Refer to the Y Multi Plot 1 graph in the Waveform Graph VI in the examples genera
271. ntrols Palette The Controls palette is available only on the front panel The Controls palette contains the controls and indicators you use to create the front panel The controls and indicators are located on subpalettes based on the types of controls and indicators Refer to the Front Panel Controls and Indicators section of Chapter 4 Building the Front Panel for more information about the types of controls and indicators Select Window Show Controls Palette or right click the front panel workspace to display the Controls palette You can place the Controls palette anywhere on the screen You can change the way the Controls palette appears Refer to the Customizing the Controls and Functions Palettes section of this chapter for more information about customizing the Controls palette Functions Palette The Functions palette is available only on the block diagram The Functions palette contains the VIs and functions you use to build the block diagram The VIs and functions are located on subpalettes based on the types of VIs and functions Refer to the Functions Overview section of Chapter 5 Building the Block Diagram for more information about the types of VIs and functions National Instruments Corporation 3 1 LabVIEW User Manual Chapter 3 LabVIEW Environment Select Window Show Functions Palette or right click the block diagram workspace to display the Functions palette You can place the Functions palette anywhere on t
272. nual Chapter 10 Local and Global Variables On the block diagram you can distinguish read locals or globals from write locals or globals the same way you distinguish controls from indicators A read local or global has a thick border similar to a control A write local or global has a thin border similar to an indicator Refer to the examples general locals 11b and examples general globals 11b for examples of using local and global variables Using Local and Global Variables Carefully Local and global variables are advanced LabVIEW concepts They are inherently not part of the LabVIEW dataflow execution model Block diagrams can become difficult to read when you use local and global variables so you should use them carefully Misusing local and global variables such as using them instead of a connector pane or using them to access values in each frame of a Sequence structure can lead to unexpected behavior in VIs Overusing local and global variables such as using them to avoid long wires across the block diagram or using them instead of data flow slows performance Refer to the Block Diagram Data Flow section of Chapter 5 Building the Block Diagram for more information about the LabVIEW dataflow execution model Initializing Local and Global Variables Race Conditions LabVIEW User Manual Verify that the local and global variables contain known data values before the VI runs Otherwise the variables might contain data that
273. o constant See the LabVIEW Help transparent See the LabVIEW Help LabVIEW 1 1 customizing 3 6 options 3 6 labview ini 3 6 last in first out variant data 5 17 launching VIs from command line See the LabVIEW Help learning and instruction directory activity A 2 examples A 2 tutorial A 2 ni com libraries adding VIs and controls 3 4 converting directories to See the LabVIEW Help converting to directories See the LabVIEW Help directory structure A 1 instrument A 1 managing 7 11 marking VIs as top level See the LabVIEW Help organization of A 1 removing VIs from See the LabVIEW Help saving VIs as 7 10 suggested location for A 3 shared 7 12 distributing VIs 7 12 user A 1 VI A 1 licenses for serving remote front panels 17 11 LIFO variant data 5 17 lights on front panel 4 10 line plots anti aliased 11 2 linking VIs to HTML or compiled help files See the LabVIEW Help listbox controls 4 12 using See the LabVIEW Help listing See displaying local variables 10 1 creating 10 2 finding objects or terminals See the LabVIEW Help initializing 10 4 memory 10 5 race conditions 10 4 read and write 10 3 using carefully 10 4 National Instruments Corporation I 17 Index localized decimal point See the LabVIEW Help localizing VIs 7 12 location for saving files A 3 locking front panel objects 4 5 VIs See the LabVIEW Help Logarithmic functions polymorphism B 7 log file
274. o not display data Do not place front panel objects too closely together Try to leave some blank space to make the front panel easier to read Blank space also prevents users from accidentally clicking the wrong control or button Assign specific names to buttons and use common terminology Use names like Start Stop and Save instead of OK Specific names make it easier for users to use the VI Use the default Lab VIEW fonts and colors LabVIEW replaces the built in fonts with comparable font families on different platforms If you select a different font LabVIEW substitutes the closest match if the font is 4 18 ni com Chapter 4 Building the Front Panel unavailable on a computer LabVIEW handles colors similarly to fonts If acolor is not available on a computer Lab VIEW replaces it with the closest match You also can use system colors to adapt the appearance of a front panel to the system colors of any computer that runs the VI Avoid placing objects on top of other objects Placing a label or any other object over or partially covering a control or indicator slows down screen updates and can make the control or indicator flicker Designing Dialog Boxes If a VI contains consecutive dialog boxes that appear in the same screen location organize them so that the buttons in the first dialog box do not directly line up with the buttons in the next dialog box Users might double click a button in the first dialog box and unknowingly
275. o on A formal and recursive definition of the allowable input type is as follows Numeric type numeric scalar OR array numeric type OR cluster numeric types The numeric scalars can be floating point numbers integers or complex floating point numbers LabVIEW does not allow you to use arrays of arrays B 2 ni com Appendix B Polymorphic Functions Arrays can have any number of dimensions of any size Clusters can have any number of elements The output type of functions is of the same numeric representation as the input type For functions with one input the functions operate on each element of the array or cluster For functions with two inputs you can use the following input combinations e Similar Both inputs have the same structure and the output has the same structure as the inputs e One scalar One input is a numeric scalar the other is an array or cluster and the output is an array or cluster e Array of One input is a numeric array the other is the numeric type itself and the output is an array For similar inputs LabVIEW performs the function on the respective elements of the structures For example LabVIEW can add two arrays element by element Both arrays must have the same dimensionality You can add arrays with differing numbers of elements the output of such an addition has the same number of elements as the smallest input Clusters must have the same number of elements and the respective ele
276. o palettes Adding Vis and Controls to the User Library and the Instrument Library The simplest method for adding VIs and controls to the Controls and Functions palettes is to save them in the user 1ib directory When you restart LabVIEW the Functions User Libraries and Controls User Controls palettes contain subpalettes for each directory VI library 11b or menu mnu file in user lib and icons for each file in user 1ib LabVIEW automatically updates the palettes when you relaunch LabVIEW after you add files to or remove files from specific directories The Functions Instrument I O Instrument Drivers palette corresponds to the instr lib directory Save instrument drivers in this directory to make them easily accessible on the Functions palette When you add VIs or controls to the Controls and Functions palettes using this method you cannot determine the exact location of the VIs or controls on the palettes 3 4 ni com Chapter 3 LabVIEW Environment Creating and Editing Palette Views To control the exact location of the VIs and controls you add to the Controls and Functions palettes you must create a palette view LabVIEW includes four built in palette views default basic data acquisition and test amp measurement LabVIEW stores Controls and Functions palette information in the labview menus directory The menus directory contains directories that correspond to each view that you create or install If you run L
277. occur National Instruments Corporation 8 11 LabVIEW User Manual Chapter 8 Loop and Case Structures Using Events in LabVIEW Events are very useful in user interface design Use events to synchronize your actions on the front panel with block diagram execution You can use events to detect when a user changes a value closes the front panel exits the application and so on By using an Event structure to execute code specific to an event you reduce the need for the block diagram to poll the front panel to determine which actions the user performed This reduces processing time and simplifies the block diagram 3 Note Events wait only for direct user interaction on the front panel Events do not work if you use VI Server global variables local variables and so on to change VI or front panel objects programmatically Event Structures ZH 0 Timeout vf Type Refer to the LabVIEW Help for information about caveats when using Event structures and for information about available events Use the Event structure shown at left to handle events in an application As with a Case structure you can add multiple cases to the Event structure You can then configure those cases to handle one or more events When those events occur LabVIEW executes the corresponding case Place Event structures inside While Loops to handle a series of events until a terminating condition occurs Caution If you place an Event structure inside a Whil
278. ode eee eee eseeeeseceeeeeeseeeseceeeeaeseeeeaeseeeeaee 20 3 Expression Nodes 3 4 sdis 5 doses cevipinna detainee iva esea ieee dee eth eS tee ae 20 4 Polymorphism in Expression Nodes 00 cseeceeseeeeeseeseeeseeeeesecseeeeeeeeseeeaees 20 4 Using HiQ with LabVIEW ics icceet xessetce adi e ils i ee cise ates 20 5 HiQ and MATLAB Script Nodes eee eeeeeeseceeeeeeseeeseeeceseeseensecseceseceeeseseeseaeesees 20 5 Programming Suggestions for HiQ and MATLAB Scripts ee 20 6 HiQ Support Files Required with a LabVIEW Application ee eeeeeeeeeeeeees 20 7 Appendix A Organization of LabVIEW Organization of the LabVIEW Directory Structure eee cece eneeeeeeeeeseeeeaes A 1 Librarie Sensasi a a O RE E A E R S TRS A 1 Structure and SUpport sosie iiinis ersi aias A 2 Learning and Instruction ns isnin na na a a aiia A 2 Documentations psie e o NE a EEE E A cones A 2 National Instruments Corporation XV LabVIEW User Manual Contents Miscellaneous Fil roeiers e ao a E E NE a duane A 2 Macintoshi esni a a ana a aaa oe basdajistencssaraviese A 2 Suggested Location for Saving Files eee cece eseeseceseesseesececeseeseeeseceseseeseesaeesees A 3 Appendix B Polymorphic Functions Nuitieric Conversion enssins o a E iE E E B 1 Polymorphism for Numeric Functions 0 cecceesccesseceeeceseeceneeeneeeceeeeeeeeseaeesseeeeeeeens B 2 Polymorphism for Boolean FUNctions cceeceesceseceseeeeeeesceceseeeaeeesneeeaeeesaeceaeee
279. ode and select Edit In Server from the shortcut menu to edit debug compile and run in the script a native HiQ script window LabVIEW User Manual 20 6 ni com Chapter 20 Formulas and Equations Verify the data types When you create a new input or output make sure that the data type of the terminal is correct In both HiQ and MATLAB a variable can change its type during computation You can use the Error In and Error Out functions to keep track of this Create controls and indicators for the inputs and outputs so you can monitor the values that the script nodes are passing between LabVIEW and HiQ or MATLAB This allows you to pinpoint where a script node calculates a value incorrectly if necessary Take advantage of the error checking parameters for debugging information Create an indicator for the error out terminal on a script node so you can view error information at run time Formula Nodes show errors at compile time HiQ Support Files Required with a LabVIEW Application After you build a LabVIEW application that includes calls to the HiQ VIs you must consider the target computer that runs the application Calling the HiQ script node in the LabVIEW code launches HiQ If you are distributing a LabVIEW application that contains a HiQ script the target machine must have HiQ installed The following table lists which files you need based on how you use and distribute LabVIEW and HiQ Files to Distribute Software Cu
280. of complex user interface applications in particular those that present dialog boxes and sub VI windows some applications might not work properly in the context of a Web browser National Instruments recommends that you do not export these types of applications for use in a Web browser In general avoid exporting data intensive VIs for remote viewing and controlling For example front panels that have several charts increase network load which causes front panel updates to be slow Also VIs that have While Loops but no wait function limit background tasks from performing in a reasonable amount of time making front panels unresponsive when viewed or controlled remotely Additionally some VIs might not work exactly the same way from a remote computer as they do when run locally ActiveX controls embedded on a front panel do not display on a remote client because they draw and operate almost completely independent of LabVIEW If a VI presents the standard file dialog box the controller receives an error because you cannot browse a file system remotely Also the Browse button of a path control is disabled in remote panels National Instruments Corporation 17 13 LabVIEW User Manual Chapter 17 Networking in LabVIEW Clients viewing a front panel remotely might see different behavior depending on whether the front panel they are connecting to is from a built application Specifically if the front panel is from a built application any
281. ogrammatic printing Property Node pull down menus PXI R race condition range rectangle refnum relative coordinates LabVIEW User Manual Cluster that contains two 16 bit integers that represent horizontal and vertical coordinates Ability of a node to automatically adjust to data of different representation type or structure Tool to move and resize objects Program to program communication Debugging feature for checking intermediate values in a VI Tool to create probes on wires Automatic printing of a VI front panel after execution Sets or finds the properties of a VI or application Menus accessed from a menu bar Pull down menu options are usually general in nature PCI eXtensions for Instrumentation A modular computer based instrumentation platform Occurs when two or more pieces of code that execute in parallel change the value of the same shared resource typically a global or local variable Region between the limits within which a quantity is measured received or transmitted Expressed by stating the lower and upper range values Cluster that contains four 16 bit integers The first two values describe the vertical and horizontal coordinates of the top left corner The last two values describe the vertical and horizontal coordinates of the bottom right corner Reference number An identifier that LabVIEW associates with a file you open Use the refnum to indicate that you want a function
282. ollbar 7 Vertical index 4 Horizontal scrollbar Figure 9 1 Parts of a Table Programmatically Editing Strings Use the String functions located on the Functions String palette to edit strings in the following ways e Search for retrieve and replace characters or substrings within a string e Change all text in a string to upper case or lower case e Find and retrieve matching patterns within a string e Retrieve a line from a string e Rotate and reverse text within a string e Concatenate two or more strings e Delete characters from a string Refer to the examples general strings 11b for examples of using the String functions to edit strings National Instruments Corporation 9 3 LabVIEW User Manual Chapter 9 Grouping Data Using Strings Arrays and Clusters Formatting Strings LabVIEW User Manual To use data in another VI function or application you often must convert the data to a string and then format the string in a way that the VI function or application can read For example Microsoft Excel expects strings that include delimiters which Excel uses to segregate numbers or words into cells For example to write a 1D array of numerics to a spreadsheet using the Write File function you must format the array into a string and separate each numeric with a delimiter such as a tab To write an array of numerics to a spreadsheet using the Write to Spreadsheet File VI you must format the array
283. on to exit retrieval mode and return to the VI whose datalog file you were viewing Deleting a Record While in retrieval mode you can delete specific records Mark for deletion an individual record in retrieval mode by viewing that record and clicking the Trash button If you click the Trash button again the record is no longer marked for deletion Select Operate Data Logging Purge Data while in retrieval mode to delete all the records you marked for deletion If you do not select Operate Data Logging Purge Data before you click the OK button LabVIEW prompts you to delete the marked records Clearing the Log File Binding Use log file binding to associate a VI with the datalog file to use when logging or retrieving front panel data You can have two or more datalog files associated with one VI This might help you test or compare the VI data For example you could compare the data logged the first time you run the VI to the data logged the second time you run the VI To associate more 13 16 ni com Chapter 13 File 1 0 than one datalog file with a VI you must clear the log file binding by selecting Operate Data Logging Clear Log File Binding LabVIEW prompts you to specify a datalog file the next time you run the VI either with automatic logging enabled or when you choose to log data interactively Changing the Log File Binding Change the log file binding to log front panel data to or retrieve front panel data from a diff
284. ons Switches and Lights Use the Boolean controls and indicators located on the Controls Boolean and Controls Classic Controls Boolean palettes to simulate buttons switches and lights Use Boolean controls and indicators to enter and display Boolean TRUE FALSE values For example if you are monitoring the temperature of an experiment you can place a Boolean warning light on the front panel to indicate when the temperature goes above a certain level Use the shortcut menu to customize the appearance of Boolean objects and how they behave when you click them Text Entry Boxes Labels and Path Displays LabVIEW User Manual Use the string and path controls and indicators located on the Controls String amp Path and Controls Classic Controls String amp Path palettes to simulate text entry boxes and labels and to enter or return the location of a file or directory String Controls and Indicators Enter or edit text in a string control on the front panel by using the Operating tool or the Labeling tool By default new or changed text does not pass to the block diagram until you terminate the edit session You terminate the edit session by clicking elsewhere on the panel changing to a different window clicking the Enter button on the toolbar or pressing the lt Enter gt key on the numeric keypad Pressing the lt Enter gt key on the keyboard enters a carriage return Macintosh and Sun Pressing the lt Return gt key on t
285. ont panel The Text Settings pull down menu contains the following built in fonts e Application Font Default font used for Controls and Functions palettes and text in new controls e System Font Used for menus e Dialog Font Used for text in dialog boxes When you transfer a VI that contains one of these built in fonts to another platform the fonts correspond as closely as possible The Text Settings pull down menu also has Size Style Justify and Color submenu items Font selections you make from any of these submenus apply to objects you selected For example if you select a new font while you have a knob and a graph selected the labels scales and digital displays all change to the new font LabVIEW preserves as many font attributes as possible when you make a change For example if you change several objects to the Courier font the objects retain their size and styles if possible When you use the Text Settings dialog box LabVIEW changes the objects you select to the text characteristics you select If you select one of the built in fonts or the current font LabVIEW changes the selected objects to the font and size associated with that font National Instruments Corporation 4 17 LabVIEW User Manual Chapter 4 Building the Front Panel When you work with objects that have multiple pieces of text like slides font changes you make affect the objects or text you currently have selected For example if you select
286. ont panel objects appear as terminals on the block diagram Refer to Chapter 5 Building the Block Diagram for more information about the block diagram 2 2 ni com Chapter 2 Introduction to Virtual Instruments The VI in Figure 2 2 shows several primary block diagram objects terminals functions and wires gt 01 gadsub vi Terminals Figure 2 2 Example of a Block Diagram and Corresponding Front Panel The terminals represent the data type of the control or indicator For example a DBL terminal shown at left represents a double precision floating point numeric control or indicator Refer to the Control and Indicator Data Types section of Chapter 5 Building the Block Diagram for more information about data types in LabVIEW and their graphical representations Terminals are entry and exit ports that exchange information between the front panel and block diagram Data you enter into the front panel controls a and b in Figure 2 2 enter the block diagram through the control terminals The data then enter the Add and Subtract functions When the Add and Subtract functions complete their internal calculations they produce new data values The data flow to the indicator terminals where they exit the block diagram reenter the front panel and appear in front panel indicators National Instruments Corporation 2 3 LabVIEW User Manual Chapter 2 Introduction to Virtual Instruments Nodes Wires Structures
287. ontrols Arrays amp Cluster and Controls Classic Controls Array amp Cluster palettes to create arrays and clusters of other controls and indicators Refer to the Grouping Data with Arrays and Clusters section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about arrays and clusters The Array amp Cluster palettes also contain standard error cluster controls and indicators the variant control and the tab control Refer to the Error Clusters section of Chapter 6 Running and Debugging VIs for more information about error clusters Refer to the Handling Variant Data section of Chapter 5 Building the Block Diagram for more information about the variant control Tab Controls Use tab controls to overlap front panel controls and indicators in a smaller area A tab control consists of pages and tabs Place front panel objects on each page of a tab control and use the tab as the selector for displaying different pages You can place an unlimited number of front panel objects on a tab control Tab controls are useful when you have several front panel objects that are used together or during a specific phase of operation For example you might have a VI that requires the user to first configure several settings National Instruments Corporation 4 11 LabVIEW User Manual Chapter 4 Building the Front Panel Listboxes LabVIEW User Manual before a test can start then allows the user to modify asp
288. ontrols and indicators data type table 5 3 error 6 9 file See file I O I O name controls and indicators 4 14 icons 2 4 creating 7 8 editing 7 8 printing 14 3 images See graphics impedance of transmission lines 12 4 importing graphics 4 4 incrementally running VIs 6 4 indexes of arrays 9 8 display 9 11 indexing loops 8 4 For Loops 8 4 While Loops 8 5 indicators 4 1 2D 4 7 3D 4 7 ActiveX 18 2 array 4 11 Boolean 4 10 using See the LabVIEW Help changing to controls 4 2 classic 4 7 clearing See the LabVIEW Help cluster 4 11 color box 4 9 color ramp 4 9 coloring 4 4 configuring 4 1 creating on block diagram See the LabVIEW Help data types table 5 2 digital 4 9 displaying optional elements 4 2 National Instruments Corporation l 15 Index enumerated type advanced 4 13 grouping and locking 4 5 guidelines for using on front panel 4 18 hidden See the LabVIEW Help hiding See also the LabVIEW Help optional elements 4 2 high color 4 7 I O name 4 14 low color 4 7 numeric 4 8 using See the LabVIEW Help optional 7 7 path 4 10 using See the LabVIEW Help printing 14 3 refnum 4 15 using See the LabVIEW Help replacing 4 2 required 7 7 resizing 4 5 in relation to window size 4 5 rotary 4 8 slide 4 8 string 4 10 display types 9 2 tab 4 11 terminals table 5 2 type definitions 4 1 user interface design 4 18 Inf infinity floatin
289. oop whose value determines the number of times the For Loop executes its subdiagram VI whose front panel block diagram or Icon Editor is the active window Special parametric plot x t y t z t where the parameter runs over a given interval Delta Difference Ax denotes the value by which x changes from one index to the next See data acquisition Utility that guides you through naming and configuring DAQ analog and digital channels Available in the Data Neighborhood of Measurement amp Automation Explorer Windows or DAQ Channel Wizard Macintosh DAQ Process of acquiring data typically from A D or digital input plug in devices Condition in a dataflow programming language in which a node cannot execute until it receives data from another node See also artificial data dependency Programming system that consists of executable nodes that execute only when they receive all required input data and produce output automatically when they execute LabVIEW is a dataflow system File that stores data as a sequence of records of a single arbitrary data type that you specify when you create the file Although all the records in a datalog file must be a single type that type can be complex For example you can specify that each record is a cluster that contains a string a number and an atray Generally to acquire data and simultaneously store it in a disk file LabVIEW file I O VIs and functions can log data For
290. opriate code After you build a custom menu build a Case structure on the block diagram that executes or handles each item in the custom menu This process is called menu selection handling LabVIEW handles all application items implicitly In Figure 15 1 the Get Menu Selection function reads the menu item the user selects and passes the menu item into the Case structure where the menu item executes Current V s Meni Bx ire item tag output of the Get Menu Selection function to the Case Structure Figure 15 1 Block Diagram Using Menu Handling If you know that a certain menu item takes a long time to process wire a Boolean control to the block menu input of the Get Menu Selection function and set the Boolean control to TRUE to disable the menu bar so the user cannot select anything else on the menu while LabVIEW processes the menu item Wire a TRUE value to the Enable Menu Tracking function to enable the menu bar after LabVIEW processes the menu item National Instruments Corporation 15 3 LabVIEW User Manual Programmatically Controlling Vis You can access the VI Server through block diagrams ActiveX technology and the TCP protocol to communicate with VIs and other instances of LabVIEW so you can programmatically control VIs and LabVIEW You can perform VI Server operations on a local computer or remotely across a network For more information Refer to the LabVIEW Help for more informatio
291. or VI to perform an operation on the open file Picture coordinates relative to the current location of the pen G 12 ni com representation resizing handles ring control sample scalar scale scope chart Scroll tool SCXI sequence local Sequence structure shift register shortcut menu slider National Instruments Corporation G 13 Glossary Subtype of the numeric data type of which there are signed and unsigned byte word and long integers as well as single double and extended precision floating point numbers Angled handles on the corner of objects that indicate resizing points Special numeric control that associates 32 bit integers starting at 0 and increasing sequentially with a series of text labels or graphics Single analog or digital input or output data point Number that a point on a scale can represent A single value as opposed to an array Scalar Booleans and clusters are explicitly singular instances of their respective data types Part of chart graph and some numeric controls and indicators that contains a series of marks or points at known intervals to denote units of measure Numeric indicator modeled on the operation of an oscilloscope Tool to move through windows Signal Conditioning eXtensions for Instrumentation The National Instruments product line for conditional low level signals within an external chassis near sensors so only high level signals in a noisy
292. or monitor settings National Instruments Corporation 4 7 LabVIEW User Manual Chapter 4 Building the Front Panel Slides Knobs Dials and Digital Displays Use the numeric controls and indicators located on the Controls Numeric and Controls Classic Controls Numeric palettes to simulate slides knobs dials and digital displays The palette also includes color boxes and a color ramp for setting color values Use numeric controls and indicators to enter and display numeric data Slide Controls and Indicators The slide controls and indicators include vertical and horizontal slides a tank and a thermometer Change the value of a slide control or indicator by using the Operating tool to drag the slider to a new position by clicking a point of the slide object or by using the optional digital display If you drag the slider to a new position and the VI is running during the change the control passes intermediate values to the VI depending on how often the VI reads the control Slide controls or indicators can display more than one value Right click the object and select Add Slider from the shortcut menu to add more sliders The data type of a control with multiple sliders is a cluster that contains each of the numeric values Refer to the Clusters section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about clusters Rotary Controls and Indicators The rotary controls and indicators includ
293. or more information about artificial data dependency Creating Configuration Files Use the Configuration File VIs located on the Functions File I O Configuration File VIs palette to read and create standard Windows configuration settings ini files and to write platform specific data such as paths in a platform independent format so that you can use the files these VIs generate across multiple platforms Refer to the examples file config 11b for examples of using the Configuration File VIs Sy Note The standard extension for Windows configuration settings files is ini but the Configuration File VIs work with files with any extension provided the content is in the correct format Refer to the Windows Configuration Settings File Format section of this chapter for more information about configuring the content LabVIEW User Manual 13 12 ni com Chapter 13 File 1 0 Using Configuration Settings Files A standard Windows configuration settings file is a specific format for storing data in a text file You can programmatically access data within the ini file easily because it follows a specific format For example consider a configuration settings file with the following contents Data Value 7 2 You can use the Configuration File VIs to read this data as shown in Figure 13 6 This VI uses the Read Key VI to read the key named Value from the section called Data This VI works regardless of how the file changes provid
294. oration 11 9 LabVIEW User Manual Chapter 11 Graphs and Charts Multiplot XY Graph Data Types The multiplot XY graph accepts an array of plots where a plot is a cluster that contains an x array and a y array The multiplot XY graph also accepts an array of clusters of plots where a plot is an array of points A point is a cluster that contains an x value and a y value Refer to the XY Graph VI in the examples general graph gengraph 11b for an example of multiplot XY graph data types Waveform Charts LabVIEW User Manual The waveform chart is a special type of numeric indicator that displays one or more plots Refer to the examples general graphs charts 11b for examples of waveform charts You can pass charts a single value or multiple values at a time As with the waveform graph LabVIEW interprets the data as points on the graph and increments the x index by one starting at x 0 The chart treats these inputs as new data for a single plot The chart redraws less frequently when you pass it multiple points at a time To pass data for multiple plots to a waveform chart you can bundle the data together into a cluster of scalar numerics where each numeric represents a single point for each of the plots If you want to pass multiple points for plots in a single update wire an array of clusters of numerics to the chart Each numeric represents a single y value point for each of the plots If you cannot determine the number of
295. orm File I O palette to send waveforms to files You can write waveforms to spreadsheet text or datalog files If you expect to use the waveform you create only in a VI save the waveform as a datalog file 10g Refer to the When to Use Datalog Files section of this chapter for more information about datalogging The VI in Figure 13 3 acquires multiple waveforms displays them on a graph and writes them to a Microsoft Excel spreadsheet file 13 10 ni com Chapter 13 File 1 0 Export Waveforms to Spreadsheet File vi Figure 13 3 Writing Multiple Waveforms to a Spreadsheet File Reading Waveforms from Files Use the Read Waveform from File VI located on the Functions Waveform Waveform File I O palette to read waveforms from a file After you read a single waveform you can add or edit waveform data type components with the Build Waveform function located on the Functions Waveform palette or you can extract waveform components with the Get Waveform Attribute function located on the Functions Waveform palette The VI in Figure 13 4 reads a waveform from a file edits the dt component of the waveform and plots the edited waveform to a graph Read Waveform from File vi 4c My Documents waveforms xls Figure 13 4 Reading a Waveform from a File The Read Waveform from File VI also reads multiple waveforms from a file The VI returns an array of waveform data types which you
296. orphic VIs and Functions ssesssesseesseessseessesresrsresreesresreresresesresrsestesrneestsresreerst 5 13 Polymorphic VISsrnniinnensnnna sea E AERE R o 5 13 Building Polymorphic VIs esessseessseeseerssesseerssesrssreresreresresrsresresese 5 14 Polymorphic FUNCtHONS wi c csccccesegsescetsescesescees cvbesvegessuses sdgebsundgsedescapdeodeastees 5 16 Handling Variant Data sensin anniina noai 5 16 Numeric Units and Strict Type Checking ieee ec ceeeeesseceeeeeeseetaeeseeeseeseenaeeeenaes 5 17 Units and Strict Type Checking oe cseceseeseceseeeceeeeseseeeseeeeeeeeeaees 5 18 Block Diagram Data FLOW 1 2 3 iccs cccce ss sest legdesesiesegscbeadagad sabes sesascustssesescebdesesescapdeeesasiass 5 20 Data Dependency and Artificial Data Dependency eee eeeeeeeeeeeee 5 20 Missing Data Dependencies 0 00 eee ee eeceeseeeeeeeeeseeeseeseeseeeseeseees 5 21 Data Flow and Managing Memory qu eeeeceeeeeseeeeeeseeseeseeeseceeeeaeeneeeaeeeees 5 21 Designing the Block Diagram o iiccicse3ssccsesciveesastacadecdssenceas cabdevesaseashdeeies cobiecstescapaseesansds 5 22 Chapter 6 Running and Debugging Vis Running VAS 223 esd i ci esi ead end Rivtee ths cantina ve coe sendin E EEA th ects hee cea dene conan i 6 1 Configuring How a VI Runs 00 eee cece ceceseeeeetseceeeeaeeeeeaeeneesaesneeeaeenees 6 1 Comecting Broken VIS aroen e a E SAR apes A EREE 6 2 Finding Causes for Broken VIS eseesseeseesseeesresrsresreresresrsres
297. orporation 5 13 LabVIEW User Manual Chapter 5 Building the Block Diagram Building Polymorphic Vis Build your own polymorphic VIs when you perform the same operation on different data types You can build polymorphic VIs only in the LabVIEW Professional Development System For example if you want to perform the same mathematical operation on a single precision floating point numeric an array of numerics or a waveform you could create three separate Vis Compute Number Compute Array and Compute Waveform When you need to perform the operation you place one of these VIs on the block diagram depending on the data type you use as an input Instead of manually placing a version of the VI on the block diagram you can create and use a single polymorphic VI The polymorphic Compute VI contains three instances of the VI as shown in Figure 5 2 a Oe 1 Compute 2 Compute Number 3 Compute Array 4 Compute Waveform Figure 5 2 Example of a Polymorphic VI LabVIEW User Manual 5 14 ni com Chapter 5 Building the Block Diagram The Compute VI statically links the correct instance of the VI based on the data type you wire to the Compute subVI on the block diagram as shown in Figure 5 3 1 Compute 2 Compute Number 3 Compute Array 4 Compute Waveform Figure 5 3 Polymorphic VI Calling a SubVI Polymorphic VIs differ from most VIs in that they do not have a block diagram or a fron
298. osoft Developer s Network documentation Inside OLE by Kraig Brockschmidt second edition and Essential COM by Don Box for more information about ActiveX For more information Refer to the LabVIEW Help for more information about using ActiveX technology ActiveX Objects Properties Methods and Events ActiveX enabled applications include objects that have exposed properties and methods that other applications can access Objects can be visible to the users such as buttons windows pictures documents and dialog boxes or invisible to the user such as application objects You access an application by accessing an object associated with that application and setting a property or invoking a method of that object Refer to the Manipulating Application and VI Settings section of Chapter 16 Programmatically Controlling VIs for more information about objects properties and methods Events are the actions taken on an object such as clicking a mouse pressing a key or running out of memory Whenever these actions occur to the object the object sends an event to alert the ActiveX container along with the event specific data National Instruments Corporation 18 1 LabVIEW User Manual Chapter 18 ActiveX Refer to the ActiveX Event Template VI and the List ActiveX Events VI in the examples comm axevent 11b and the FamilyTree VI and the MultiEvents VI in the examples comm directory for examples of using ActiveX events
299. ou can display up to 16 bits on a single plot and so on You also can plot the same bit two or more times on a single plot Refer to Appendix D Masking Digital Data for more information about masking digital data 3D Graphs 3 Note The 3D graph controls are available only for Windows in the LabVIEW Full and Professional Development Systems For many real world data sets such as the temperature distribution on a surface joint time frequency analysis and the motion of an airplane you need to visualize data in three dimensions With the 3D graphs you can visualize three dimensional data and alter the way that data appear by modifying the 3D graph properties National Instruments Corporation 11 15 LabVIEW User Manual Chapter 11 Graphs and Charts The following 3D graphs are available e 3D Surface Draws a surface in 3D space When you drop this control on the front panel LabVIEW wires it to a subVI that receives the data that represent the surface e 3D Parametric Draws a complex surface in 3D space When you drop this control on the front panel LabVIEW wires it to a subVI that receives the data that represent the surface e 3D Curve Draws a line in 3D space When you drop this control on the front panel LabVIEW wires it to a subVI that receives the data that represent the line Use the 3D graphs in conjunction with the 3D Graph VIs located on the Functions Graphics amp Sound 3D Graph Properties palette to plot c
300. ou click Placing a terminal or icon on top of a wire makes it appear as if a connection exists when it does not Use the Coloring tool and right click the block diagram workspace to add or change the color of the workspace Increase the space between crowded or tightly grouped objects by pressing the lt Ctrl gt key and use the Positioning tool to click the block diagram workspace While holding the key combination drag out a region the size you want to insert 5 22 ni com Chapter 5 Building the Block Diagram Macintosh Press the lt Option gt key Sun Press the lt Meta gt key Linux Press the lt Alt gt key A rectangle marked by a dashed border defines where space will be inserted Release the key combination to add the space Refer to the LabVIEW Development Guidelines manual for more information about designing the block diagram National Instruments Corporation 5 23 LabVIEW User Manual Running and Debugging VIs Torun a VI you must wire all the subVIs functions and structures with the data types the terminals expect Sometimes a VI produces data or runs ina way you do not expect You can use LabVIEW to configure how a VI runs and to identify problems with block diagram organization or with the data passing through the block diagram For more information Refer to the LabVIEW Help for more information about debugging VIs Running VIs Running a VI executes the operation for which you designed t
301. our data interactively so you can select when to log the data Logging your data automatically logs the data each time you run the VI Sy Note A waveform chart logs only one data point at a time with front panel datalogging If you wire an array to the chart indicator the datalog file contains a subset of the array the chart displays National Instruments Corporation 13 15 LabVIEW User Manual Chapter 13 File 1 0 Viewing the Logged Front Panel Data Interactively LabVIEW User Manual After you log data you can view it interactively by selecting Operate Data Logging Retrieve The data retrieval toolbar appears as shown in Figure 13 7 RJC H 0 0 6 22 00 5 26 55 PM 320 Figure 13 7 Data Retrieval Toolbar The highlighted number indicates the data record you are viewing The numbers in square brackets indicate the range of records you logged for the current VI You log a record each time you run the VI The date and time indicate when you logged the selected record View the next or previous record by clicking the increment or decrement arrows You also can use the up and down arrow keys on your keyboard In addition to the data retrieval toolbar the front panel appearance changes according to the record you select in the toolbar For example when you click the increment arrow and advance to another record the controls and indicator display the data for that particular record at the time you logged the data Click the OK butt
302. pause glyph or a solid glyph in black and white indicates a VI that is currently paused An exclamation point glyph indicates that the subVI is suspended A VI can be suspended and paused at the same time Determining the Current Instance of a SubVI When you pause a subVI the Call list pull down menu in the toolbar lists the chain of callers from the top level VI down to the subVI This is not the same list you see when you select Browse This VI s Callers which lists all calling VIs regardless of whether they are currently running Use the Call list menu to determine the current instance of the subVI if the block diagram contains more than one instance When you select a VI from the Call list menu its block diagram opens and LabVIEW highlights the current instance of the subVI Commenting Out Sections of Block Diagrams You can run a VI with a section of the block diagram disabled similar to commenting out a section of code in a text based programming language Disable a section of the block diagram to determine if the VI performs better without it Place the section you want to disable inside a Case structure and use a Boolean constant to run both cases Refer to the Case Structures section of Chapter 8 Loop and Case Structures for more information about using Case structures You also can create a copy of the VI and delete that section of the block diagram from the copy Discard the version of the VI you decide not to use Disab
303. plays are not as interactive as the built in LabVIEW controls but you can use them to visualize information in ways the built in controls currently cannot Use the Plot Waveform VI to create a plot with slightly different functionality than built in LabVIEW graphs Using the Polar Plot VI as a SubVI Use the Polar Plot VI to draw specific contiguous quadrants of a polar graph or the entire graph at once As with the built in LabVIEW graphs you can specify the color of the components include a grid and specify the range and format for the scales The Polar Plot VI provides a large amount of functionality in a single VI Consequently the VI includes complicated clusters for inputs You can use default values and custom controls to decrease the complexity of the VI Instead of creating your own cluster input on the block diagram copy a custom control from the Polar Plot Demo VI in the examples picture demos 11b and place it on your front panel Using the Waveform Plot VI as a SubVI Use the Plot Waveform VI which emulates the behavior of the built in waveform graph to draw waveforms in a variety of styles including points connected lines and bars As with the built in LabVIEW waveform graphs you can specify the color of the components include a grid and specify the range and format for the scales The Waveform Plot VI provides a large amount of functionality in a single VI Consequently the VI includes complicated clusters for i
304. ple Waveforms in a 2D Array of Numerics Refer to the examples general arrays 11b for more examples of arrays LabVIEW User Manual 9 10 ni com Chapter 9 Grouping Data Using Strings Arrays and Clusters Restrictions for Arrays You can create an array of almost any data type with the following exceptions e You cannot create an array of arrays However you can use a multidimensional array or use the Build Cluster Array function to create an array of clusters where each cluster contains one or more arrays e You cannot create an array of non XY graphs because a graph is an array data type and an array cannot contain another array However you can have an array of non XY graphs if the graph is in a cluster e You cannot create an array of charts Creating Array Controls Indicators and Constants Create an array control or indicator on the front panel by placing an array shell on the front panel as shown in Figure 9 7 and dragging a data object or element which can be a numeric Boolean string path refnum or cluster control or indicator into the array shell Figure 9 7 Array Shell The array shell automatically resizes to accommodate the new object whether a small Boolean control or a large 3D graph To display a particular element on the front panel either type the index number in the index display or use the arrows on the index display to navigate to that number To create an array constant on t
305. r example if the selector is an integer and you specify cases for 1 2 and 3 you must specify a default case to execute if the input value is 4 or any other valid integer value Case Selector Values and Data Types You can enter a single value or lists and ranges of values in the case selector label For lists use commas to separate values For numeric ranges specify a range as 10 20 meaning all numbers from 10 to 20 inclusively You also can use open ended ranges For example 100 represents all numbers less than or equal to 100 You also can combine lists and ranges forexample 5 6 7 10 12 13 14 When you enter values that contain overlapping ranges in the same case selector label the Case structure redisplays the label in a more compact form The previous example redisplays as 10 12 14 For string ranges a range of a c includes all of a and b but not c A range of a c c includes the ending value of c When you enter string and enumerated values in a case selector label the values display in quotation marks for example red green and blue However you do not need to type the quotation marks when you enter the values unless the string or enumerated value contains a comma or range symbol or In a string value use special backslash codes for non alphanumeric characters such as r for a carriage return n for a line feed and t for a tab Refer to the LabVIEW Help for a list of these
306. r instrument for more information about the configuration utilities The IMAQ session control is a unique identifier that represents the connection to the hardware 4 14 ni com Chapter 4 Building the Front Panel Waveform Control Use the waveform control located on the Controls I O or Controls Classic Controls I O palettes to manipulate individual data elements of a waveform Refer to the Waveform Data Type section of Chapter 11 Graphs and Charts for more information about the waveform data type References to Objects or Applications Use the reference number controls and indicators located on the Controls Refnum and Controls Classic Controls Refnum palettes to work with files directories devices and network connections Use the control refnum to pass front panel object information to subVIs Refer to the Controlling Front Panel Objects section of Chapter 16 Programmatically Controlling VIs for more information about control refnums A reference number or refnum is a unique identifier for an object such as a file device or network connection When you open a file device or network connection LabVIEW creates a refnum associated with that file device or network connection All operations you perform on open files devices or network connections use the refnums to identify each object Use a refnum control or indicator to pass a refnum into or out of a VI For example use arefnum control or indicator to modify the
307. rance and Help behavior 15 1 saving VIs for previous 7 11 controlling on Web 17 9 VI object controlling programmatically 16 1 manipulating settings 16 3 controlling when called as subVIs 7 3 VI Server 16 3 copying A 3 VI search path correcting 6 2 editing See the LabVIEW Help creating descriptions 14 2 VI Server 16 1 creating tip strips 14 2 Application object 16 3 debugging techniques 6 3 building applications 16 2 developing 7 1 Call By Reference Node 16 7 distributing 7 12 calling other instances of LabVIEW on documenting 14 1 Web 16 1 dragging and dropping See the LabVIEW calling VIs remotely 16 1 Help capabilities 16 1 error handling 6 8 controlling front panel objects 16 8 examples 1 3 Invoke Node 16 4 executable manipulating VI settings 16 3 debugging See the LabVIEW Help networking and 17 1 finding See the LabVIEW Help Property Node 16 3 hierarchy 7 9 remote applications 16 8 launching from command line See the LabVIEW Help National Instruments Corporation l 27 LabVIEW User Manual Index libraries 7 10 loading dynamically 16 7 localizing 7 12 locking See the LabVIEW Help marking as top level in libraries See the LabVIEW Help naming 7 11 opening in run mode See the LabVIEW Help polymorphic 5 13 porting 7 12 printing 14 5 publishing on Web 17 9 reference See the LabVIEW Help removing from libraries See the LabVIEW Help reverting to last saved version
308. ration Settings File Format 00 0 0 eee eee eeeeseeeeeseeeees 13 13 Logsing Front Panel Datare sser aeia ey secueevsce suey A AEA E 13 15 Automatic and Interactive Front Panel Datalogging eee eeeeeee 13 15 Viewing the Logged Front Panel Data Interactively 00 0 0 eeeeeeeeeeeees 13 16 Deleting a Record iniii pne lie Adie Gases 13 16 Clearing the Log File Binding eee eeeeeeeeeeeeeeeeeeeeseeeees 13 16 Changing the Log File Binding eee cece cere eeeeesetseeeseeseees 13 17 LabVIEW User Manual xii ni com Contents Retrieving Front Panel Data Programmatically 0 sees eeeeseeeeeeeeeees 13 17 Retrieving Front Panel Data Using a SubVI eee 13 17 Specifying Records ee seesessseesecsececesseceasesseecseneneevees 13 18 Retrieving Front Panel Data Using File I O Functions 00 0 13 18 Chapter 14 Documenting and Printing Vis Documenting VISis icc ace iti osita E basin wees N E E E dantens 14 1 Creating VI and Object Descriptions 0 cece cece eseeeeeseeeeeeseeneetseseenseesees 14 2 Setting up the VI Revision History 00 0 ccc eee eeeeseeseceecesesseeesesseesaeeseeeaeens 14 2 Revision NUmbersse ccsseciesssscevesvescsstasastesevtvesves sepyp a capedecviyeet 14 2 Printing DOcuMentatt OM sein aranse r Us eatasd ete teed oa Seca eee keene 14 3 Saving to HTML or RTF Files eee ec ceceseeeeeeeetseeeseeseeeneens 14 3 Selecting Graphic Formats for HTML Files 14 4 Naming Conventions for Graphi
309. re not identical Formula Nodes are useful for equations that have many variables or are otherwise complicated and for using existing text based code You can copy and paste the existing text based code into a Formula Node rather than recreating it graphically Formula Nodes use type checking to make sure that array indexes are numeric data and that operands to the bit operations are integer data Formula Nodes also check to make sure array indexes are in range For arrays an out of range value defaults to zero and an out of range assignment defaults to nop to indicate no operation occurs Formula Nodes also perform automatic type conversion Using the Formula Node LabVIEW User Manual The Formula Node located on the Functions Structures and Functions Mathematics Formula palettes is a resizable box similar to the For Loop While Loop Case structure and Sequence structure However instead of containing a subdiagram the Formula Node contains one or more C like statements delimited by semicolons as in the following example As with C add comments by enclosing them inside a slash asterisk pair comment 20 2 ni com Chapter 20 Formulas and Equations int32 i float64 num rry 100 for i 1 i lt 100 i num rry i rand tandom number generator Refer to the Equations VI in the examples general structs 11b for an example of using a Formula Node Variables in the Formula Node When
310. requirements e Youcan mark VIs ina library as top level so when you open the library LabVIEW automatically opens all the top level VIs in that library nye Note LabVIEW stores many of its built in VIs and examples in VI libraries to ensure consistent storage locations on all platforms LabVIEW User Manual If you use VI libraries consider dividing your application into multiple VI libraries Put the high level VIs in one VI library and set up other libraries to contain VIs separated by function Saving changes to a VI ina library takes longer than saving changes to an individual VI because the operating system must write the changes to a larger file Saving changes to a large library also can increase memory requirements and decrease performance Try to limit the size of each library to approximately 1 MB 7 10 ni com Chapter 7 Creating Vis and SubVIs Managing Vis in Libraries Use the VI Library Manager available by selecting Tools VI Library Manager to simplify copying renaming and deleting files within VI libraries You also can use this tool to create new VI libraries and directories and convert VI libraries to and from directories Creating new VI libraries and directories and converting VI libraries to and from directories is important if you need to manage your VIs with source code control tools Before you use the VI Library Manager close all VIs that might be affected to avoid performing a file operation on a VI
311. rerreresrerrsresrsese 6 2 Common Causes of Broken VIS esseeseeeseesesesresrsrrsreersrsrsresrerrsresresrsresreeese 6 3 Debugging Techniques prcna a n E ott basie eatin seared 6 3 Execution Highhshting 0 2 30 cat pict esi etal avs see eee a 6 4 Single Steppin 2i ccatneis ands wed l he eal 6 4 Probe TOM enrera a e e EA eae sees ben RE E E EiS 6 4 Breakpointssr heiit e E A E O A A e a 6 5 S spending EXSCUtlONs iev sireeni ccsest EEEE EE TEE EEE NEEE 6 5 Determining the Current Instance of a SubV1I s es 6 6 Commenting Out Sections of Block Diagrams eseeesserersersererserereereresreees 6 6 Disabling Debugging Tools eee eee cece cecceseeesecseesseeseeeeessecsaeeseceeesaeseaesseenseeaeenaes 6 6 Undetinedior Unexpected Datari ic EE EERE RORE EE E EEE 6 7 Unexpected and Default Data in Loops ssesseesssssrserssrersrrsrsresrrersrrsresrsrrsrseese 6 7 For LOOpsva ss dscseseegee thos ET AUR EA 6 7 Wihile oops ssiseeetsstads ennan hdd eee E a ee 6 8 Default Data in Arrays is oc sicss cecwsig cesses cechactesededevs cuicevsoeheviies REAREN 6 8 Preventing Undefined Data eee ceeeccesececeeeeeeeeseeseeesecseeeaeeneeeasensenaes 6 8 Error Checking and Error Handling 00 eee cece cecceseceeeeseceeeeseeseeesecseeeaeeaeeeseeeeeaes 6 8 Checking fotEmors s cs c e esveteisevide sed tseteh a a duckie weer even ets 6 9 LabVIEW User Manual viji ni com Contents Error Handli g aioi nescitis eros is EE EE EEE ENEA 6 9 Error Clus
312. right clicking the terminal or the border of the While Loop and selecting Stop If True shown at left You also can use the Operating tool to click the conditional terminal to change the condition When a conditional terminal is Stop If True the While Loop executes its subdiagram until the conditional terminal receives a TRUE value Because the VI checks the 8 2 ni com Chapter 8 Loop and Case Structures conditional terminal at the end of each iteration the While Loop always executes at least one time The VI is broken if you do not wire the conditional terminal You also can perform basic error handling using the conditional terminal of a While Loop When you wire an error cluster to the conditional terminal only the TRUE or FALSE value of the status parameter of the error cluster passes to the terminal Also the Stop If True and Continue If True shortcut menu items change to Stop If Error and Continue while Error Refer to the Error Checking and Error Handling section of Chapter 6 Running and Debugging VIs for more information about error clusters and error handling fil The iteration terminal an output terminal shown at left contains the number of completed iterations The iteration count always starts at zero During the first iteration the iteration terminal returns 0 Add shift registers to the While Loop to pass data from the current iteration to the next iteration Refer to the Shift Registers in Loops section of this chapt
313. roblems with the VI or the block diagram data flow National Instruments Corporation Wire the error in and error out parameters at the bottom of most built in VIs and functions These parameters detect errors encountered in each node on the block diagram and indicate if and where an error occurred You also can use these parameters in the VIs you build Refer to the Error Handling section of this chapter for more information about using these parameters Use execution highlighting to watch the data move through the block diagram Single step through the VI to view each action of the VI on the block diagram Use the Probe tool to check intermediate values as a VI runs Use breakpoints to pause execution so you can single step or insert probes Suspend the execution of a subVI to edit values of controls and indicators to control the number of times it runs or to go back to the beginning of the execution of the subVI Comment out a section of the block diagram to determine if the VI performs better without it 6 3 LabVIEW User Manual Chapter 6 Running and Debugging VIs Execution Highlighting View an animation of the execution of the block diagram by clicking the Highlight Execution button shown at left Execution highlighting shows the movement of data on the block diagram from one node to another using bubbles that move along the wires Use execution highlighting in conjunction with single stepping to see how da
314. rocess Control DataSocket protocol 17 3 online technical support E 1 opc DataSocket protocol 17 3 opening VIs in run mode See the LabVIEW Help LabVIEW User Manual Index operators See nodes options setting 3 6 See also the LabVIEW Help storing 3 6 order of cluster elements 9 14 modifying 9 14 See also the LabVIEW Help order of execution 5 20 controlling with Sequence structures 8 9 out of range numbers 4 14 overflow of numbers 6 7 overlaid plots 11 6 overlapping front panel objects 4 11 overriding default function key settings See the LabVIEW Help owned labels 4 16 editing See the LabVIEW Help P palettes 3 1 changing See the LabVIEW Help color picker 4 9 Controls 3 1 customizing 3 4 customizing 3 4 Functions 3 1 customizing 3 4 inserting objects See the LabVIEW Help navigating and searching 3 2 organizing 3 5 reference See the LabVIEW Help sharing See the LabVIEW Help Tools 3 2 updating See the LabVIEW Help views 3 5 panel order setting 4 4 parameter lists See connector panes LabVIEW User Manual 1 20 parameters data types table 5 2 password protection 7 12 patents iii paths adding directories to VI search path See the LabVIEW Help controls and indicators 4 10 data type table 5 3 using See the LabVIEW Help empty 4 11 file I O 13 6 invalid 4 11 options 3 6 remote front panels 17 13 universal constants 5 4 patterns terminal 7 6
315. rom the LabVIEW Help but you must install the PDFs to do so Refer to the LabVIEW Release Notes or LabVIEW Upgrade Notes for more information about installing PDF versions of the LabVIEW manuals Refer to the LabVIEW Documentation Resources section of Chapter 1 Introduction to LabVIEW for information about accessing the PDFs in the LabVIEW Bookshelf Organization of This Manual The LabVIEW User Manual includes two sections Part I LabVIEW Concepts describes programming concepts for building applications in LabVIEW The chapters in this section introduce you to the LabVIEW programming environment and help you plan your application National Instruments Corporation xvii LabVIEW User Manual About This Manual Conventions Part II Building and Editing VIs describes LabVIEW features VIs and functions you can use to make your applications operate in specific ways The chapters in this section describe the use of each LabVIEW feature and outline each class of VIs and functions gt GI bold italic monospace monospace bold monospace italic LabVIEW User Manual The following conventions appear in this manual The symbol leads you through nested menu items and dialog box options to a final action The sequence File Page Setup Options directs you to pull down the File menu select the Page Setup item and select Options from the last dialog box This icon denotes a tip which alerts you to advisory i
316. rom the shortcut menu You also can select Tools Advanced ActiveX Property Browser The ActiveX Property Browser is an easy way to set the properties of an ActiveX control interactively but you cannot use the browser to set properties programmatically and you can use the ActiveX Property Browser only with ActiveX objects in a container The ActiveX Property Browser is not available in Run mode 18 4 ni com Chapter 18 ActiveX ActiveX Property Pages Many ActiveX objects include property pages which organize the properties associated with the object on separate tabs To access ActiveX property pages right click the object or document in the container on the front panel and select the name of the object from the shortcut menu Like the ActiveX Property Browser ActiveX property pages are an easy way to set the properties of an ActiveX control interactively but you cannot use them to set properties programmatically and you can use property pages only with ActiveX objects in a container Also property pages are not available for all ActiveX objects Property Nodes Use the Property Node to set ActiveX properties programmatically For example if you use an ActiveX control to warn a user when a temperature exceeds a limit use the Property Node to set the Value property of the object to specify the limit The following example changes the Value property of the CWButton ActiveX object which is part of the Component Works Control Libr
317. ronment 3 4 DAQ Channel Viewer 1 4 Channel Wizard 1 4 Configuration Utility 1 4 passing channel names 4 14 Solution Wizard 1 4 VIs and functions 7 3 data acquisition See DAQ data bubbles displaying during execution highlighting See the LabVIEW Help data dependency 5 20 artificial 5 20 controlling with Sequence structures 8 9 flow through parameters 13 12 missing 5 21 race conditions 10 4 data flow observing 6 4 data types Case structures 8 7 control and indicator table 5 2 converting from XML 9 7 converting to XML 9 6 HiQ table 20 6 MATLAB table 20 6 printing 14 3 waveform 11 16 dataflow programming model 5 20 managing memory 5 21 datalog file I O 13 4 creating files 13 10 datalogging 13 15 automatic 13 15 LabVIEW User Manual Index changing log file binding 13 17 clearing log file binding 13 16 deleting records 13 16 interactive 13 15 retrieving data programmatically 13 17 DataSocket 17 2 block diagram 17 6 controlling front panel objects See the LabVIEW Help formats for data 17 4 front panel 17 5 protocols 17 3 URLs 17 3 variant data 17 7 date format options 3 6 DDE 17 15 deallocating memory See the LabVIEW Help debugging broken VIs 6 2 default data 6 8 disabling debugging tools 6 6 executable VIs See the LabVIEW Help hidden wires 5 22 HiQ and MATLAB scripts 20 6 loops 6 7 options 3 6 structures See the LabVIEW Help techniques 6 3 Brea
318. rray Functions Most of the array functions accept n dimensional arrays of any type However the wiring diagrams in the function descriptions show numeric arrays as the default data type Polymorphism for String Functions String Length To Upper Case To Lower Case Reverse String and Rotate String accept strings clusters and arrays of strings and arrays of clusters To Upper Case and To Lower Case also accept numbers clusters of numbers and arrays of numbers interpreting them as ASCII codes for characters Width and precision inputs must be scalar Polymorphism for String Conversion Functions The Path To String and String To Path functions are polymorphic That is they work on scalar values arrays of scalars clusters of scalars arrays of clusters of scalars and so on The output has the same composition as the input but with the new type Polymorphism for Additional String to Number Functions To Decimal To Hex To Octal To Engineering To Fractional and To Exponential accept clusters and arrays of numbers and produce clusters and arrays of strings From Decimal From Hex From Octal and From Exponential Fract Sci accept clusters and arrays of strings and produce clusters and arrays of numbers Width and precision inputs must be scalar National Instruments Corporation B 5 LabVIEW User Manual Appendix B Polymorphic Functions Polymorphism for Cluster Functions The Bundle and Unbundle functions do not sho
319. rrently Available on Target What to Install LabVIEW application VIs with HiQ script node LabVIEW any version installed no HiQ installed Licensed copy of HiQ that is available with LabVIEW Executable No LabVIEW and no HiQ installed HiQ Reader enables others to view HiQ Professional Notebooks and run scripts You can distribute the HiQ Reader free from the LabVIEW Full or Professional Development System CD Refer to the National Instruments Web site at ni com to download the HiQ Reader National Instruments Corporation 20 7 LabVIEW User Manual Organization of LabVIEW This appendix describes the structure of the LabVIEW file system and the suggested locations for saving files Organization of the LabVIEW Directory Structure This section describes the structure of the LabVIEW file system for Windows Macintosh and UNIX LabVIEW installs driver software for GPIB DAQ VISA IVI Motion Control and IMAQ hardware depending on platform availability Refer to Chapter 3 Installing and Configuring Your Measurement Hardware of the LabVIEW Measurements Manual for information about configuring your hardware As described in the LabVIEW Release Notes that come with the software your LabVIEW directory contains the following groupings after you complete the installation Libraries National Instruments Corporation user 1ib Contains controls and VIs you create LabVIEW display
320. rror to the next node without executing The next node does the same thing and so on At the end of the execution flow LabVIEW reports the error Error Clusters The error clusters located on the Controls Array amp Cluster palette include the following components of information e status is a Boolean value that reports TRUE if an error occurred Most VIs functions and structures that accept Boolean data also recognize this parameter For example you can wire an error cluster to the Boolean inputs of the Stop Quit LabVIEW or Select functions If an error occurs the error cluster passes a TRUE value to the function e code is a signed 32 bit integer that identifies the error numerically A non zero error code coupled with a status of FALSE signals a warning rather than a fatal error e source is a string that identifies where the error occurred Using While Loops for Error Handling You can wire an error cluster to the conditional terminal of a While Loop to stop the iteration of the While Loop When you wire the error cluster to the conditional terminal only the TRUE or FALSE value of the status parameter of the error cluster is passed to the terminal When an error occurs the While Loop stops When an error cluster is wired to the conditional terminal the shortcut menu items Stop if True and Continue if True change to Stop on Error and Continue while Error Using Case Structures for Error Handling When you wire an error
321. rties and Methods You can get or set properties of a VI perform methods on a VI or both In Figure 16 3 LabVIEW reinitializes the front panel objects of a VI to their default values using the Invoke Node The front panel opens and displays the default values using the Property Node Before you can access properties and methods of a VI you must create a refnum to that VI with the Open VI Reference function Use the Invoke Node to invoke a method on a VI National Instruments Corporation 16 5 LabVIEW User Manual Chapter 16 Programmatically Controlling Vis Close LY Object Reference E 328 eror out san Feinitialize All To Default 4 Figure 16 3 Using VI Class Property and Invoke Nodes After you wire Open VI Reference to the Invoke Node you can access all the VI Class methods The Property Node operates similarly to the Invoke Node After you wire a VI refnum to the Property Node you can access all the VI Class properties Manipulating Application and VI Class Properties and Methods In some VIs you must access both Application and VI Class properties or methods You must open and close the Application and VI Class refnums separately as shown in Figure 16 4 Figure 16 4 shows how to determine the VIs in memory on a local computer and to display the path to each of the VIs on the front panel To find all the VIs in memory you must access an Application Class property To determ
322. ry pull down menu The Allow Debugging contains a checkmark by default Each error has a numeric code and a corresponding error message Use the LabVIEW error handling VIs functions and parameters to manage errors For example if LabVIEW encounters an error you can display the error 6 8 ni com Chapter 6 Running and Debugging Vis message in a dialog box Use error handling in conjunction with the debugging tools to find and manage errors National Instruments strongly recommends error handling Checking for Errors No matter how confident you are in the VI you create you cannot predict every problem a user can encounter Without a mechanism to check for errors you know only that the VI does not work properly Error checking tells you why and where errors occur When you perform any kind of input and output I O consider the possibility that errors might occur Almost all I O functions return error information Include error checking in VIs especially for I O operations file serial instrumentation data acquisition and communication and provide a mechanism to handle errors appropriately Checking for errors in VIs can help you identify the following problems e You initialized communications incorrectly or wrote improper data to an external device e An external device lost power is broken or is working improperly e You upgraded the operating system software which changed the path to a file or the functionality of a
323. s cccescesecesceeeneceseceeeeceaeeeseeenees 18 1 ActiveX VIs Functions Controls and Indicators 0 cccccccccsssecceeesseeeeeees 18 2 LabVIEW as an ActiveX Cheit ecasmia tenangno a a a 18 3 Accessing an ActiveX Enabled Application sseesseseseeesseesssrerrsrsrrsrsresresesee 18 3 Inserting an ActiveX Object on the Front Panel s ssssssesesssssessssssisesesssereese 18 4 Settings Active X Propert eSegre neo is EEE E ERE barets 18 4 ActiveX Property BrOWSer sssessseeesesseeessesrsesrerrsrestererensesrrsresesee 18 4 ACUVEX Property PaSes s sc J c cissel ocd HovevedatinssuatieHesesstiessdssus souseran 18 5 Property Node Siiran e aean ea S see Sauhists EEES 18 5 LabVIEW as an ActiveX Seryet ororen ORE REE REE 18 6 Support for Custom ActiveX Automation Interfaces 0 0 cece ce eeeeeeeeees 18 6 Using Constants to Set Parameters in ActiveX VIS ccceceessesssseseeesseeseseeseeseeeeees 18 6 Chapter 19 Calling Code from Text Based Programming Languages Call Library Function Nodes c4iscecuck idence datauiae Llane halves 19 1 Code Tnterface Nodier ii nare aE EEA EAREN RETO EE E 19 1 Chapter 20 Formulas and Equations Methods for Using Equations in LabVIEW essessesssseessesesressesrsresrssesresreresreresresersrseses 20 1 Formula NOdGS is eeir a esac NE EE REE RE E E REEE RE a Sent 20 2 Using the Formula Nodecsss rmi eeeeseeseceseeseeesecsecnseeseeeaeseeseseeseseaeeatens 20 2 Variables in the Formula N
324. s directory structure of LabVIEW Macintosh A 2 organization A 1 disabling debugging tools 6 6 sections of a block diagram debugging VIs 6 6 disk space checking See the LabVIEW Help options 3 6 disk streaming 13 7 displaying auto constant labels See the LabVIEW Help chain of callers 6 6 errors 6 2 front panels remotely 17 10 hidden front panel objects See the LabVIEW Help optional elements in front panel objects 4 2 terminals 5 2 tip strips See the LabVIEW Help warnings 6 2 National Instruments Corporation l 9 Index distributing objects on the front panel See the LabVIEW Help VIs 7 12 DLLs building 7 12 distributing VIs 7 12 calling from LabVIEW 19 1 Do Loops See While Loops documentation conventions used in this manual xviii directory structure A 2 guide 1 1 introduction to this manual xvii online library E 1 organization of this manual xvii PDF library 1 1 using this manual xvii using with other resources 1 1 documenting VIs 14 1 creating object and VI descriptions 14 2 creating tip strips 14 2 help files 14 4 linking to help files you create See the LabVIEW Help printing 14 3 programmatically 14 3 revision history 14 2 dots coercion 5 12 dragging and dropping See the LabVIEW Help drawing See also graphics smooth updates See the LabVIEW Help drivers instrument E 1 LabVIEW See the LabVIEW Help drop through clicking S
325. s 3 5 clients 18 3 constants for setting parameters 18 6 containers 18 2 controls 18 2 custom interfaces 18 6 events 18 1 for running script nodes 20 2 functions 18 2 indicators 18 2 inserting objects on front panel 18 4 invoking methods See the LabVIEW Help networking and 17 1 objects 18 1 properties 18 1 Property Browser 18 4 Property Node 18 5 property pages 18 5 remote front panels 17 13 selecting custom interfaces 18 3 servers 18 6 setting parameters using constants 18 6 setting properties 18 4 setting properties programmatically 18 5 VI Server 16 1 viewing properties 18 4 VIs 18 2 National Instruments Corporation adding controls to libraries 3 4 directories to VI search path See the LabVIEW Help graphic to VI icon See the LabVIEW Help terminals to functions 5 9 VIs to libraries 3 4 add on toolsets 1 1 in palettes 3 6 advanced functions 5 9 aligning objects See the LabVIEW Help Alliance Program E 1 animated front panel images 17 10 annotations 4 16 editing See the LabVIEW Help anti aliased line plots 11 2 Apple events 17 15 Application Builder See stand alone applications application control functions 5 9 application font 4 17 application notes 1 3 Application object manipulating settings 16 3 VI Server 16 3 applications building stand alone 7 12 distributing VIs 7 12 building VI Server 16 2 arithmetic See equations arrays 9 8 auto
326. s 8 2 While Loops 8 3 patterns 7 6 removing from functions 5 9 selector 8 7 sequence local 8 9 wiring 5 10 text dragging and dropping See the LabVIEW Help entry boxes 4 10 finding See the LabVIEW Help formatting 4 17 ring controls 4 13 text files creating 13 8 file I O 13 2 writing numeric data to 9 5 thermometers See also numerics slide controls and indicators 4 8 threads running multiple See the LabVIEW Help time format options 3 6 LabVIEW User Manual Index time functions 5 8 timing controlling 8 6 tip strips control captions See the LabVIEW Help creating 14 2 displaying over terminals See the LabVIEW Help displaying See the LabVIEW Help toolbar 3 4 tools palette 3 2 selecting manually See the LabVIEW Help toolsets 1 1 in palettes 3 6 tracking development See documenting VIs training customer E 1 Transmission Control Protocol 17 14 transmission lines 12 4 transparent labels See the LabVIEW Help objects See the LabVIEW Help trees variant data 5 17 troubleshooting resources E 1 troubleshooting See debugging tunnels 8 1 input and output 8 8 tutorial 1 1 type completion 4 12 listboxes 4 12 ring controls 4 13 type controls enumerated 4 13 advanced 4 13 type definitions 4 1 LabVIEW User Manual 1 26 U UDP 17 14 undefined data 6 7 arrays 6 8 checking for 6 7 For Loops 6 7 Inf infinity 6 7 NaN not a number 6 7 preventing 6 8 Wh
327. s See the LabVIEW Help running 6 1 saving 7 10 sharing 7 12 strictly typed refnums 16 7 unlocking See the LabVIEW Help upgrading 7 11 VISA passing resource names 4 14 VXI configuring 1 3 VIs 1 3 W warnings button 6 2 displaying 6 2 displaying by default See the LabVIEW Help waveform charts 11 10 controls and indicators data type table 5 3 LabVIEW User Manual 1 28 data type 11 16 functions 5 8 graphs 11 7 data types 11 8 graphics 12 3 waveforms reading from files 13 11 writing to files 13 10 weakly typed control references 16 9 Web calling other instances of LabVIEW 16 1 controlling VIs 17 10 creating HTML documents 17 9 publishing VIs 17 9 technical support E 1 viewing front panels 17 10 Web Publishing Tool 17 9 Web Server 17 9 clients for remote front panels LabVIEW 17 12 multiple 17 11 Web browser 17 12 controlling VIs 17 10 enabling 17 9 licenses for serving remote front panels 17 11 options 17 9 viewing front panels 17 10 Web support from National Instruments E 1 While Loops 8 2 auto indexing 8 5 conditional terminals 8 2 controlling timing 8 6 default data 6 8 error handling 6 10 infinite 8 3 iteration terminals 8 3 remote front panels 17 13 shift registers 8 5 using See the LabVIEW Help ni com window size defining See the LabVIEW Help window titles in Functions palette See the LabVIEW Help wires 2 4 broken 5 12 moving
328. s controls on the Controls User Controls palette and VIs on the Functions User Libraries palette This directory does not change if you upgrade or remove LabVIEW vi 1ib Contains libraries of built in VIs including GPIB analysis and DAQ VIs LabVIEW displays these VIs in related groups on the Functions palette Do not save files into vi 1ib because LabVIEW overwrites these files when you upgrade instr 1ib Contains instrument drivers used to control PXI VXI GPIB serial and computer based instruments When you install National Instruments instrument drivers place them in this directory and LabVIEW adds them to the Instrument I O Instrument Drivers palette A 1 LabVIEW User Manual Appendix A Organization of LabVIEW Structure and Support Learning and Instructi Documentation Miscellaneous File Macintosh menus Contains files LabVIEW uses to configure the structure of the Controls and Functions palettes resource Contains additional support files for the Lab VIEW application Do not save files into this directory because LabVIEW overwrites these files when you upgrade project Contains files that become items on the LabVIEW Tools menu templates Contains templates for common VIs www Location of HTML files you can access through the Web Server on activity Contains VIs you use to complete the activities in the LabVIEW Tutorial The activity solution directory contains the completed VIs for e
329. s lines shapes and pixmaps Pixmaps of unflattened data are 2D arrays of color where each value corresponds to a color The first row of the Picture Functions palette contains VIs you use to draw points and lines A point is a cluster of two 16 bit signed integers that represent the x and y coordinates of a pixel When you draw the picture remembers the position of the graphics pen For most of the Picture Functions VIs you must specify absolute coordinates that is relative to the origin 0 0 With Draw Line VI and Move Pen VI you can specify either absolute or relative coordinates Relative coordinates are relative to the current location of the pen You can use the Move Pen VI to change the location of the pen without drawing Only the Draw Point VI Move Pen VI Draw Line VI and Draw Multiple Lines VI change the location of the pen The second row of the Picture Functions palette contains VIs you use to draw a filled shape Each of these VIs draws a shape in a rectangular area of a picture You specify a rectangle as a cluster of four values that represent the left top right and bottom pixels With the Draw Arc VI the rectangle describes the size of an oval Additional parameters specify the portion of the oval the arc you want to draw The third row of the Picture Functions palette contains VIs you use to draw text in a picture The Get Text Rect VI does not draw any text Instead you use it to calculate the size of a boun
330. s located on the Functions File I O palette to perform the following tasks e Open and close files e Read from and write to files e Create directories and files you specify in the path control e Retrieve directory information e Write strings numbers arrays and clusters to files The File I O palette also includes VIs that perform common file I O tasks Refer to Chapter 13 File I O for more information about using the File I O VIs and functions Waveform Functions LabVIEW User Manual Use the Waveform functions located on the Functions Waveform palette to perform the following tasks e Build waveforms that include the waveform values channel information and timing information e Extract individual data elements from a waveform e Edit individual data elements of a waveform 5 8 ni com Chapter 5 Building the Block Diagram Refer to Part II DAQ Basics of the LabVIEW Measurements Manual for more information about creating and using waveforms in VIs Application Control Functions Use the Application Control functions located on the Functions Application Control palette to programmatically control VIs and LabVIEW applications on your local computer or across a network Refer to Chapter 16 Programmatically Controlling VIs for more information about using the Application Control functions Advanced Functions Use the Advanced functions located on the Functions Advanced palette to call code from librari
331. s provide a platform independent format for information and data Some of the more common applications of strings include the following e Creating simple text messages e Passing numeric data as character strings to instruments and then converting the strings to numerics Storing numeric data to disk To store numerics in an ASCII file you must first convert numerics to strings before writing the numerics to a disk file Instructing or prompting the user with dialog boxes On the front panel strings appear as tables text entry boxes and labels Edit and manipulate strings with the String functions on the block diagram You format strings for use in other applications such as word processing applications and spreadsheets or for use within other VIs and functions National Instruments Corporation 9 1 LabVIEW User Manual Chapter 9 Grouping Data Using Strings Arrays and Clusters Strings on the Front Panel Use the string control and indicator located on the Controls String amp Path palette to simulate text entry boxes and labels Refer to the String Controls and Indicators section of Chapter 4 Building the Front Panel for more information about string controls and indicators String Display Types Right click a string control or indicator on the front panel to select from the display types shown in Table 9 1 The table also shows an example message in each display type Table 9 1 String Display Types
332. se tools from the Tools menu e Windows Measurement amp Automation Explorer helps you configure National Instruments hardware and software National Instruments Corporation 1 3 LabVIEW User Manual Chapter 1 Introduction to LabVIEW e Macintosh The NI DAQ Configuration Utility helps you configure National Instruments DAQ hardware e Macintosh The DAQ Channel Wizard helps you define what type of device is connected to the DAQ hardware channels After you define a channel the DAQ Channel Wizard remembers the settings e Windows and Macintosh The DAQ Channel Viewer lists the configured DAQ channels e Windows and Macintosh The DAQ Solution Wizard helps you find solutions for common DAQ applications You can choose from example VIs or create custom VIs LabVIEW User Manual 1 4 ni com Introduction to Virtual Instruments LabVIEW programs are called virtual instruments or VIs because their appearance and operation imitate physical instruments such as oscilloscopes and multimeters Every VI uses functions that manipulate input from the user interface or other sources and display that information or move it to other files or other computers A VI contains the following three components e Front panel Serves as the user interface e Block diagram Contains the graphical source code that defines the functionality of the VI Icon and connector pane Identifies the VI so that you can use the VI in another VI
333. ser Manual Chapter 5 Building the Block Diagram Using Wires to Link Block Diagram Objects LabVIEW User Manual You transfer data among block diagram objects through wires Each wire has a single data source but you can wire it to many VIs and functions that read the data Wires are different colors styles and thicknesses depending on their data types A broken wire appears as a dashed black line Refer to the LabVIEW Quick Reference Card for more information about wire data types Wire stubs are the truncated wires that appear next to unwired terminals when you move the Wiring tool over a VI or function node They indicate the data type of each terminal A tip strip also appears listing the name of the terminal After you wire a terminal the wire stub for that terminal does not appear when you move the Wiring tool over its node A wire segment is a single horizontal or vertical piece of wire A bend in a wire is where two segments join The point at which three or four wire segments join is a junction A wire branch contains all the wire segments from junction to junction terminal to junction or terminal to terminal if there are no junctions in between Figure 5 1 shows a wire segment bend and junction 1 Segment 2 Bend 3 Junction Figure 5 1 Wire Segment Bend and Junction You can wire terminals vertically or horizontally depending on the direction in which you first move the Wiring tool The wire conn
334. ss into the display as new columns on the graph or chart If you want rows to appear as rows on the display wire a 2D array data type to the graph or chart right click the graph or chart and select Transpose Array from the shortcut menu The array indexes correspond to the lower left vertex of the block of color The block of color has a unit area which is the area between the two points as defined by the array indexes The intensity graph or chart can display up National Instruments Corporation 11 11 LabVIEW User Manual Chapter 11 Graphs and Charts Color Mapping LabVIEW User Manual to 256 discrete colors To display large quantities of data on an intensity chart make sure enough memory is available After you plot a block of data on an intensity chart the origin of the Cartesian plane shifts to the right of the last data block When the chart processes new data the new data appear to the right of the old data When a chart display is full the oldest data scroll off the left side of the chart This behavior is similar to the behavior of strip charts Refer to the Chart Update Modes section of this chapter for more information about these charts Refer to the examples general graphs intgraph 11b for examples of the intensity chart and graph You can set the color mapping interactively for intensity graphs and charts the same way you define the colors for a color ramp numeric control Refer to the Color Ramps section of Chapt
335. string indicator Tabbed text Use tabbed text as in a spreadsheet to publish data in arrays LabVIEW interprets tabbed text as an array of data wav data Use wav data to publish a sound to a VI or function Variant data Use variant data to subscribe to data from another application such as a ComponentWorks control 17 4 ni com Chapter 17 Networking in LabVIEW Using DataSocket on the Front Panel Use front panel DataSocket connections to publish or subscribe to live data in a front panel object When you share the data of a front panel object with other users you publish data When users retrieve the published data and view it on their front panel users subscribe to the data DataSocket connections differ from Web Server and ActiveX connections because you can use DataSocket connections directly from the front panel without any block diagram programming Each front panel control or indicator can publish or subscribe to data through its own DataSocket connection Front panel DataSocket connections publish only the data not a graphic of the front panel control so the VIs that subscribe through a DataSocket connection can perform their own operations on the data You can set the value of a front panel control directly on the front panel and then publish the data or you can build a block diagram wire the output of a VI or function to an indicator and publish the data from that indicator Typical scenarios for using DataSock
336. sult in errors because word processing applications format text with different fonts colors styles and sizes that the spreadsheet file VIs cannot process If you want to write numbers and text to a spreadsheet or word processing application use the String functions located on the Functions String palette and the Array functions located on the Functions Array palette to format the data and to combine the strings Then write the data to a file Refer to Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about using these functions to format and combine data Formatting and Writing Data to Files LabVIEW User Manual Use the Format Into File function to format string numeric path and Boolean data as text and to write the formatted text to a file Often you can use this function instead of separately formatting the string with the Format Into String function and writing the resulting string with the Write Characters To File VI or Write File function You can append or overwrite existing data in a file with the Format Into File function Use the Seek function to set a file mark in a refnum After the Format into File function writes the resulting string the file mark is set to the end of the text 13 8 ni com Chapter 13 File 1 0 Refer to the Formatting Strings section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about formatting strings Scanning Data from Fi
337. t Although the positions of block diagram elements do not determine execution order avoid wiring from right to left to keep the block diagram organized and easy to understand Only wires and structures determine execution order Avoid creating a block diagram that occupies more than one or two screens If a block diagram becomes large and complex it can be difficult to understand or debug Decide if you can reuse some components of the block diagram in other VIs or if a section of the block diagram fits together as a logical component If so divide the block diagram into subVIs that perform specific tasks Using subVIs helps you manage changes and debug the block diagrams quickly Refer to the SubVIs section of Chapter 7 Creating VIs and SubVIs for more information about subVIs Use the error handling VIs functions and parameters to manage errors on the block diagram Refer to the Error Checking and Error Handling section of Chapter 6 Running and Debugging VIs for more information about handling errors Improve the appearance of the block diagram by wiring efficiently Poor wire organization might not produce errors but it can make the block diagram difficult to read or debug or make the VI appear to do things it does not do Avoid wiring under a structure border or between overlapped objects because LabVIEW might hide some segments of the resulting wire Avoid placing objects on top of wires Wires connect only those objects y
338. t click to display a temporary version of the Tools palette at the location of the cursor LabVIEW User Manual If automatic tool selection is enabled and you move the cursor over objects on the front panel or block diagram LabVIEW automatically selects the corresponding tool from the Tools palette Toggle automatic tool selection 3 2 ni com Chapter 3 LabVIEW Environment by clicking the Automatic Tool Selection button in the Tools palette or by pressing the lt Shift Tab gt keys Menus and the Toolbar Use the menu and toolbar items to operate and modify front panel and block diagram objects Use the toolbar buttons to run VIs Menus The menus at the top of a VI window contain items common to other applications such as Open Save Copy and Paste and other items specific to LabVIEW Some menu items also list shortcut key combinations Macintosh The menus appear at the top of the screen ay Note Some menu items are unavailable while a VI is in run mode Shortcut Menus The most often used menu is the object shortcut menu All LabVIEW objects and empty space on the front panel and block diagram have associated shortcut menus Use the shortcut menu items to change the look or behavior of front panel and block diagram objects To access the shortcut menu right click the object front panel or block diagram Macintosh Press the lt Command gt key and click the object front panel or block diagram Shortcut Men
339. t is otherwise complicated Expression Nodes use the value you pass to the input terminal as the value of the variable The output terminal returns the value of the calculation For example consider this simple equation xxXx 33x x 4 5 The block diagram in the following figure uses Numeric functions to represent this equation Use an Expression Node as shown in the following figure to create a much simpler block diagram result cont P x x 33 x 5 i ca Polymorphism in Expression Nodes LabVIEW User Manual The input terminal of an Expression Node is the same data type as the control or constant you wire to it The output terminal is the same data type as the input terminal The data type of the input can be any non complex scalar number array of non complex scalar numbers or cluster of non complex scalar numbers With arrays and clusters the expression node applies the equation to each element of an input array or cluster 20 4 ni com Chapter 20 Formulas and Equations Using HiQ with LabVIEW HiQ is a high performance interactive problem solving environment where you can analyze visualize and document real world science and engineering problems HiQ uses a virtual notebook interface and a programming language called HiQ Script The notebook has pages sections and tabs where you can place and arrange objects such as text numerics and graphs Use the VIs located on the Functions
340. t numbers from one data type to another Boolean Functions Use the Boolean functions located on the Functions Boolean palette to perform logical operations on single Boolean values or arrays of Boolean values such as the following tasks e Change a TRUE value to a FALSE value and vice versa e Determine which Boolean value to return if you receive two or more Boolean values e Convert a Boolean value to a number either 1 or 0 e Perform compound arithmetic on two or more Boolean values LabVIEW User Manual 5 6 ni com String Functions Array Functions Cluster Functions Chapter 5 Building the Block Diagram Use the String functions located on the Functions String palette to perform the following tasks e Concatenate two or more strings e Extract a subset of strings from a string e Search for and replace characters or subsets of strings in a string e Convert data into strings e Formata string for use in a word processing or spreadsheet application Refer to the Strings section of Chapter 9 Grouping Data Using Strings Arrays and Clusters for more information about using the String functions Use the Array functions located on the Functions Array palette to create and manipulate arrays such as the following tasks e Extract individual data elements from an array e Add individual data elements to an array e Split arrays Refer to the Arrays section of Chapter 9 Grouping Data Using Strings
341. t panel Consider the following issues when you build polymorphic VIs National Instruments Corporation All VIs you include in the polymorphic VI must have the same connector pane pattern because the connector pane of the polymorphic VI matches the connector pane of the VIs you use to create the polymorphic VI The inputs and outputs on the connector pane of each instance of the VI must correspond to the inputs and outputs on the connector pane of the polymorphic VI The VIs you use to build polymorphic VIs do not have to consist of the same subVIs and functions Each of the front panels of the VIs do not have to have the same number of objects However each front panel must have at least the same number of controls and indicators that make up the connector pane of the polymorphic VI You can create an icon for a polymorphic VI You cannot use polymorphic VIs in other polymorphic VIs 5 15 LabVIEW User Manual Chapter 5 Building the Block Diagram When you create complete documentation for a VI that includes a polymorphic subVI the polymorphic VI and the VIs it invokes appear in the List of SubVIs Polymorphic Functions Functions are polymorphic to varying degrees none some or all of their inputs can be polymorphic Some function inputs accept numerics or Boolean values Some accept numerics or strings Some accept not only scalar numerics but also arrays of numerics clusters of numerics arrays of clusters of num
342. t shows one item of data such as a pulse or wave scrolling partway across the chart from left to the right A sweep display is similar to an EKG display A sweep works similarly to a scope except it shows the old data on the right and the new data on the left separated by a vertical line Overlaid Versus Stacked Plots You can display multiple plots on a chart by using a single vertical scale called overlaid plots or by using multiple vertical scales called stacked plots Figure 11 2 shows examples of overlaid plots and stacked plots 11 6 ni com Chapter 11 Graphs and Charts Figure 11 2 Charts with Overlaid and Stacked Plots Refer to the Charts VI in the examples general graphs charts 11b for examples of different kinds of charts and the data types they accept Waveform and XY Graphs Waveform graphs display evenly sampled measurements XY graphs display any set of points evenly sampled or not Figure 11 3 shows examples of a waveform graph and an XY graph 0 6 0 4 0 2 La ca ae el ay a I a O 5 1015 20 25 30 35 40 45 50 Figure 11 3 Waveform and XY Graphs The waveform graph plots only single valued functions as in y f x with points evenly distributed along the x axis such as acquired time varying waveforms The XY graph is a general purpose Cartesian graphing object that plots multivalued functions such as circular shapes or waveforms with National I
343. t structure can handle multiple filter events only if the data the events return are identical If you try to group two events that do not return identical data such as Key Down and Mouse Down the VI is broken Event Example The following example shows an Event structure configured with the Menu Selection User event This event captures menu selections made using the user defined menu named sample rtm ItemTag returns which menu item was selected and MenuRef returns the refnum to the menu bar Refer to the examples general uievents 11b for more examples of using events ZH 0 Menu Selection User v Ea nye Note If you configure the Event structure to handle menu events and have the Get Menu Selection function configured for the same menu item the Event structure takes precedence and LabVIEW ignores the Get Menu Selection function In any given VI you should use either the Event structure or the Get Menu Selection function LabVIEW User Manual 8 14 ni com Grouping Data Using Strings Arrays and Clusters Strings Use strings arrays and clusters to group data Strings group sequences of ASCII characters Arrays group data elements of the same type Clusters group data elements of mixed types For more information Refer to the LabVIEW Help for more information about grouping data using strings arrays and clusters A string is a sequence of displayable or non displayable ASCII characters String
344. t subVIs Select Help Find Examples for examples of block diagrams and subVIs Designing Projects with Multiple Developers If multiple developers work on the same project define programming responsibilities interfaces and coding standards up front to ensure the development process and the application work well Keep master copies of the project VIs on a single computer and institute a source code control policy Consider using the LabVIEW Professional Development System which includes source code control tools that simplify file sharing The tools also include a utility to compare VIs and view the changes that were made between versions of VIs Refer to the Source Code Control section of Chapter 2 Incorporating Quality into the Development Process in the LabVIEW Development Guidelines manual for more information about using source code control Using Built In Vis and Functions LabVIEW includes VIs and functions to help you build specific applications such as data acquisition VIs and functions VIs that access other VIs and VIs that communicate with other applications You can use these VIs as subVIs in your application to reduce development time Refer to the SubVIs section of this chapter for more information about subVIs Building Instrument Control and Data Acquisition Vis and Functions LabVIEW User Manual You can use the built in VIs and functions to control external instruments such as oscilloscopes and to acquire da
345. t the count implicitly with auto indexing Refer to the Auto Indexing to Set the For Loop Count section of this chapter for more information about setting the count implicitly The iteration terminal an output terminal shown at left contains the number of completed iterations The iteration count always starts at zero During the first iteration the iteration terminal returns 0 Both the count and iteration terminals are signed long integers If you wire a floating point number to the count terminal LabVIEW rounds it and coerces it to within range If you wire 0 or a negative number to the count terminal the loop does not execute Add shift registers to the For Loop to pass data from the current iteration to the next iteration Refer to the Shift Registers in Loops section of this chapter for more information about adding shift registers to a loop Similar to a Do Loop or a Repeat Until Loop in text based programming languages a While Loop shown at left executes a subdiagram until a condition is met The While Loop executes the subdiagram until the conditional terminal an input terminal receives a specific Boolean value The default behavior and appearance of the conditional terminal is Continue If True shown at left When a conditional terminal is Continue If True the While Loop executes its subdiagram until the conditional terminal receives a FALSE value You can change the behavior and appearance of the conditional terminal by
346. ta such as readings from a thermocouple Use the Instrument I O VIs and functions located on the Functions Instrument I O palette to control external instruments To control instruments in LabVIEW you must have the correct hardware installed powered on and operating on your computer The VIs and functions you 7 2 ni com Chapter 7 Creating Vis and SubVIs use to control instruments depend on the instrumentation communication protocols your hardware supports Refer to the LabVIEW Measurements Manual for more information about building VIs to control instruments Use the Data Acquisition VIs and functions located on the Functions Data Acquisition palette to acquire data from DAQ devices To use these VIs you must have the NI DAQ driver software and DAQ hardware installed Refer to the LabVIEW Measurements Manual for more information about installing the NI DAQ driver software and DAQ hardware and building VIs to acquire data After you acquire data you can use the built in Analyze Report Generation and Mathematics VIs and functions to analyze generate reports and perform mathematical operations on that data Refer to the Analysis Concepts manual for more information about analysis and mathematical concepts in LabVIEW Building Vis That Access Other Vis Use the Application Control VIs and functions located on the Functions Application Control palette to control how VIs behave when called as subVIs or run by the user You can use
347. ta move from node to node through a VI 3 Note Execution highlighting greatly reduces the speed at which the VI runs Single Stepping p Probe Tool e LabVIEW User Manual If the error out cluster reports an error the error value appears next to error out with a red border If no error occurs OK appears next to error out with a green border Refer to the Error Clusters section of this chapter for more information about error clusters Single step through a VI to view each action of the VI on the block diagram as the VI runs The single stepping buttons shown at left affect execution only in a VI or subVI in single step mode Enter single step mode by clicking the Step Over or Step Into button on the block diagram toolbar Move the cursor over the Step Over Step Into or Step Out button to view a tip strip that describes the next step if you click that button You can single step through subVIs or run them normally If you single step through a VI with execution highlighting on an execution glyph shown at left appears on the icons of the subVIs that are currently running Use the Probe tool shown at left to check intermediate values on a wire as a VI runs Use the Probe tool if you have a complicated block diagram with a series of operations any one of which might return incorrect data Use the Probe tool with execution highlighting single stepping and breakpoints to determine if and where data are incorrect If data ar
348. ter and Notify Events There are two types of events notify and filter Notify events tell LabVIEW that a user action has already occurred such as when a user changes the value of a control For example you can write a VI that notifies the Event structure on the block diagram when the user clicks a button on the front panel Because the value changes when the user clicks the button the Event structure is notified The Event structure can handle multiple notify events at one time If you configure a single case to handle multiple notify events only the data that is common to all handled event types is available National Instruments Corporation 8 13 LabVIEW User Manual Chapter 8 Loop and Case Structures Filter events allow control over how the user interface behaves With filter events you can validate or change the event data before the user interface can process it or you can discard the event data entirely preventing the change from affecting the VI For example you can configure a Menu Selection event that does not allow the user to interactively close the front panel of the VI You also can configure a Key Down event to modify all characters typed into a string control so they are uppercase or you can modify the event to filter unwanted characters The existence of terminals on the right side of the Event structure such as the Discard terminal identify a filter event nye Note Unlike notify events a single case in the Even
349. ters inre aoaiina iaaa aa aaaeei epinis 6 10 Using While Loops for Error Handling eseeeeeeeeeeseeseeereerreesrsesree 6 10 Using Case Structures for Error Handling sseeeeeeeseeereeeereereeeeee 6 10 Chapter 7 Creating Vis and SubVls Planning and Designing Your Project 0 ec eeseescesceeeecenceseneceeeesaeceeeeeeesaeeeseeeneeeeaes 7 1 Designing Projects with Multiple Developers eee ec eeeeeeseeeeeeeeneenees 7 2 Using Built In VIs and Functions 20 0 eee eceeeeseeesceeeseceseceeeeseeseesaeeaeceseeaeeeseaeseeeeaees 7 2 Building Instrument Control and Data Acquisition VIs and Functions 7 2 Building VIs That Access Other VIS ceeeeeseeseeseessceseeseeesesseeeseseeeeseenees 7 3 Building VIs That Communicate with Other Applications 7 3 SUB VIS serere ea A A E EAR E A ET E A a hantemnleds 7 4 Watching for Common Operations 0 0 0 0 eee cece eeeeeeseceeeeseceseeseeseeeaseseeaeenes 7 4 Setting up the Connector Panesco eaii 7 6 Setting Required Recommended and Optional Inputs And QUEPUS seecss septs eases svocseepboees E Ea AEE ted 7 7 Creating an Con 5 s ce0 teivntss a a E ann nes wa ea ees 7 8 Creating SubVIs from Sections Of a VI ieee eseeeseeseeeecesecneetsesseseseesees 7 8 Designing Sub Vs raa a deeds Need Beacon eee tae 7 8 Viewing the Hierarchy of VIS 20 0 eee cece eeeeeseceeeeseesseesecseeeseeeseeseeneesaeenaes 7 9 Saving Vis Te a Rees ash reeks R E A Mes dale Oh le RHIAN 7 10 Advantages of Saving V
350. tform right click Macintosh Press lt Command gt click to perform the same action as a right click National Instruments Corporation xix LabVIEW User Manual Part I LabVIEW Concepts This part describes programming concepts for building applications in LabVIEW The chapters in this section introduce you to the LabVIEW programming environment and help you plan your application Part I LabVIEW Concepts contains the following chapters National Instruments Corporation Chapter 1 Introduction to LabVIEW describes LabVIEW its extensive documentation and tools to help you design and build VIs Chapter 2 Introduction to Virtual Instruments describes the components of virtual instruments or VIs Chapter 3 LabVIEW Environment describes the LabVIEW palettes tools and menus you use to build the front panels and block diagrams of VIs This chapter also describes how to customize the LabVIEW palettes and set several work environment options Chapter 4 Building the Front Panel describes how to build the front panel of a VI Chapter 5 Building the Block Diagram describes how to build the block diagram of a VI Chapter 6 Running and Debugging VIs describes how to configure how a VI runs and to identify problems with block diagram organization or with the data passing through the block diagram Chapter 7 Creating VIs and SubVIs describes how to create your own VIs and subVIs distribute VIs and build stand
351. th values such as Not a Path Not a Refnum and Default Directory The universal file constants are located on the Functions File I O File Constants palette User Defined Constants The Functions palette includes constants organized by type such as Boolean numeric ring enumerated type color box listbox string array cluster and path constants Create a user defined constant by right clicking an input terminal of a VI or function and selecting Create Constant from the shortcut menu You cannot change the value of user defined constants when the VI is running 5 4 ni com Chapter 5 Building the Block Diagram You also can create a constant by dragging a front panel control to the block diagram LabVIEW creates a constant that contains the value of the front panel control at the time you dragged it to the block diagram The front panel control remains on the front panel Changing the value of the control does not affect the constant value and vice versa Use the Operating or Labeling tool to click the constant and edit its value If automatic tool selection is enabled double click the constant to switch to the Labeling tool and edit the value Block Diagram Nodes Nodes are objects on the block diagram that have inputs and or outputs and perform operations when a VI runs They are analogous to statements operators functions and subroutines in text based programming languages LabVIEW includes the following types of nodes
352. that represent the X and Y coordinates as shown in Figure 9 4 index 0 1 2 3 4 5 6 X coord 0 4 2 2 3 3 3 2 24 18 19 Y coord 0 2 0 5 13 23 26 1 9 1 2 Figure 9 4 Graph in an Array of Points National Instruments Corporation 9 9 LabVIEW User Manual Chapter 9 Grouping Data Using Strings Arrays and Clusters The previous examples use 1D arrays A 2D array stores elements in a grid It requires a column index and a row index to locate an element both of which are zero based Figure 9 5 shows an 6 column by 4 row 2D array which contains 6 x 4 24 elements Column Index 0 1 2 3 4 5 Row Index ano Figure 9 5 6 Column by 4 Row 2D Array For example a chessboard has eight columns and eight rows for a total of 64 positions Each position can be empty or have one chess piece You can represent a chessboard as a 2D array of strings Each string is the name of the piece that occupies the corresponding location on the board or an empty string if the location is empty You can generalize the 1D array examples in Figures 9 3 and 9 4 to two dimensions by adding a row to the array Figure 9 6 shows a collection of waveforms represented as a 2D array of numerics The row index selects the waveform and the column index selects the point on the waveform Figure 9 6 Multi
353. that you pass to the picture indicator for display You can connect the pictures you create with the Picture Functions VIs only to a picture indicator or to the picture input of a Picture Functions VI LabVIEW draws the picture when it updates the picture indicator on an open front panel Each Picture Functions VI concatenates its drawing instruction to the previous drawing instruction s of the picture input and output If the picture input is unwired the picture output returns a blank rectangular drawing area The following block diagram uses the Draw Rect VI to draw two overlapping rectangles right iF e color blue Luszi colorfbive Cus black in BAW7 T sen The black in B W Boolean control indicates whether the rectangle is black or white if you display it on a monochrome monitor If you create a set of VIs that use the picture indicator and you want the VIs to run on all monitors you must use the black in B W control 12 2 ni com Chapter 12 Graphics and Sound VIs Picture Plots Vis Use the Picture Plot VIs located on the Functions Graphics amp Sound Picture Plots palette to create common types of graphs using the picture indicator These graphs include a polar plot a waveform graph display a Smith plot and a graph scale The Picture Plot VIs use low level drawing functions to create a graphical display of your data and customize the drawing code to add functionality These graphical dis
354. the data so that when you save the data to a file you easily can identify the value s name s and type of the data from the tags that describe the data For example if you convert an array of temperature values to XML and save that data to a text file you 9 6 ni com Chapter 9 Grouping Data Using Strings Arrays and Clusters easily can identify the temperature values by locating the lt Value gt tag that identifies each temperature Use the Flatten to XML function located on the Functions Advanced Data Manipulation palette to convert a LabVIEW data type to XML format The following example generates 100 simulated temperatures plots the array of temperatures to a chart converts the array of numbers to the XML format and writes the XML data to the temperatures xml file 4C measurements temperatures xml Use the Unflatten from XML function located on the Functions Advanced Data Manipulation palette to convert a data type in the XML format into LabVIEW data The following example reads the 100 temperatures in the temperatures xml file and plots the array of temperatures to a chart LC measurements temperatures xml Read Characters From File vi hart of Temperatures iy Note Although you can flatten LabVIEW Variant data to XML attempting to unflatten variant data from XML results in an empty LabVIEW variant LabVIEW XML Schema LabVIEW converts data to an established XML schem
355. the user 1ib directory by default because all files and directories in user 1ib automatically appear in the palettes National Instruments Corporation 3 5 LabVIEW User Manual Chapter 3 LabVIEW Environment Representing Toolsets in the Palettes Toolsets you install in vi 1ib addons automatically appear on the top level of the Controls and Functions palettes after you restart LabVIEW If you have toolsets installed elsewhere you can move the toolsets to the addons directory for easier access Caution Do not save your own VIs and controls in the vi 1ib directory because LabVIEW overwrites these files when you upgrade Save your VIs and controls in the user lib directory to add them to the Controls and Functions palettes Setting Work Environment Options LabVIEW User Manual Select Tools Options to customize LabVIEW Use the Options dialog box to set options for paths performance and disk issues front panels block diagrams undo debugging tools colors fonts printing the History window time and date formats and other LabVIEW features Use the top pull down menu in the Options dialog box to select among the different categories of options How LabVIEW Stores Options You do not have to edit options manually or know their exact format because the Options dialog box does it for you LabVIEW stores options differently on each platform Windows LabVIEW stores options in a labview ini file in the LabVIEW directory The
356. ting objects See the LabVIEW Help designing 5 22 finding terminals See the LabVIEW Help fonts 4 17 functions 5 6 inserting objects See the LabVIEW Help labels 4 16 creating See the LabVIEW Help editing See the LabVIEW Help resizing See the LabVIEW Help nodes 5 5 objects 5 1 options 3 6 password protecting 7 12 planning 7 1 printing 14 5 removing objects See the LabVIEW Help reordering objects See the LabVIEW Help replacing objects See the LabVIEW Help spacing objects evenly See the LabVIEW Help ni com structures 8 1 using See the LabVIEW Help terminals 5 1 adding to functions 5 9 control and indicator table 5 2 displaying 5 2 front panel objects and 5 1 removing from functions 5 9 variant data 5 16 VI Server 16 1 wiring automatically 5 11 wiring manually 5 10 5 12 BMP files 12 6 Boolean controls and indicators 4 10 comparing values C 1 data type table 5 2 using See the LabVIEW Help Boolean functions 5 6 polymorphism B 4 Breakpoint tool debugging VIs 6 5 highlighting breakpoints See the LabVIEW Help broken VIs common causes 6 3 correcting 6 2 displaying errors 6 2 broken wires 5 12 buffered data local variables 10 5 buffers variant data 5 17 building block diagram 5 1 front panel 4 1 instrument driver applications See the LabVIEW Help measurement and automation systems E 1 polymorphic VIs 5 14 National Instruments Corporation l 3 Ind
357. tion of this chapter for more information about communications protocols LabVIEW supports Windows Refer to Chapter 18 ActiveX for more information about using ActiveX technology with LabVIEW as an ActiveX server or client Using DataSocket Technology LabVIEW User Manual Use National Instruments DataSocket technology to share live data with other VIs and other applications such as National Instruments ComponentWorks on the Web or on your local computer DataSocket pulls together established communication protocols for measurement and automation in much the same way a Web browser pulls together different Internet technologies DataSocket technology provides access to several input and output mechanisms from the front panel through the DataSocket Connection dialog box Right click a front panel object and select Data Operations DataSocket Connection from the shortcut menu to display the DataSocket Connection dialog box You publish write or subscribe to read data by specifying a URL in much the same way you specify URLs in a Web browser 17 2 ni com Specifying a URL Chapter 17 Networking in LabVIEW For example if you want to share the data in a thermometer indicator on the front panel with other computers on the Web publish the thermometer data by specifying a URL in the DataSocket Connection dialog box Users on other computers subscribe to the data by placing a thermometer on their front panel and selecting the
358. tor The cluster contains the name of the control or indicator as a string the data type as an array of 16 bit integers and the data as flattened strings as shown in Figure 5 4 5 16 ni com Chapter 5 Building the Block Diagram name I Thermometer type desc flat data loll Figure 5 4 Cluster of Flattened Numeric Data However using flattened data has limitations because LabVIEW cannot coerce flattened data Also attempting to unflatten a flattened integer as an extended precision floating point number fails Use the variant data type to work with data independently of data type instead of flattening the data Refer to the Flattened Data section of the LabVIEW Data Storage Application Note for more information about flattening and unflattening data You can add attributes to further identify the variant data For example an attribute to the variant data type can identify from which data acquisition device channel the data came Variant data also are useful when you write to or read from memory in LabVIEW and perform operations that involve stacks last in first out queues first in first out smart buffers or trees These kinds of operations treat data independently of the data types Numeric Units and Strict Type Checking You can associate physical units of measure such as meters or kilometers second with any numeric control that has floating point representation Units for a control appear in a s
359. ts only the data that is common to all handled event types is available a The Event Selector label at the top of the Event structure shown at left displays which case is currently selected including the events handled for that case 3 Note Like a Case structure the Event structure supports tunnels However by default you do not have to wire the Event structure output tunnels for every case All unwired tunnels use the default value for the tunnel data type Right click a tunnel and deselect Use Default If Unwired from the shortcut menu to revert to the default Case structure behavior where tunnels must be wired in all cases Events are grouped into classes such as Application VI and Control The event data always includes a reference to the object that triggered the event If a single case is handling multiple events for controls of different VI Server classes the event source control reference is the common parent class of all classes For example if you configure a single case in the Event structure to handle events for a digital numeric control and a color ramp control the type of the event source control reference is Numeric because the digital numeric and color ramp controls are in the Numeric class Configuring Events Right click the Event structure border and select Edit Events Handled by This Case from the shortcut menu to display the Edit Events dialog box Use this dialog box to edit single or multiple cases Fil
360. tte 8 Scale legend 11 Label 3 Grid mark 6 Cursor mover 9 X scale Figure 11 1 Graph Elements You add most of the items listed in the legend above by right clicking the graph selecting Visible Items from the shortcut menu and selecting the appropriate element Graph Cursors Cursors on graphs allow you to read the exact value of a point on a plot The cursor value displays in the cursor legend Add a cursor to a graph by right clicking the graph selecting Visible Items Cursor Legend from the shortcut menu and clicking anywhere in a cursor legend row to activate a cursor Use the Positioning tool to expand the cursor legend to add multiple cursors You can place cursors and a cursor display on all graphs and you can label the cursor on the plot You can set a cursor to lock onto a plot and you can move multiple cursors at the same time A graph can have any number of cursors LabVIEW User Manual 11 4 ni com Chapter 11 Graphs and Charts Refer to the Zoom Graph VI in the examples general graphs zoom 11b for an example of reading cursor values and programmatically zooming in and out of a graph using the cursors Scale Options Graphs can automatically adjust their horizontal and vertical scales to reflect the data you wire to them This behavior is called autoscaling Turn autoscaling on or off by right clicking the graph and selecting X Scale Autoscale X or Y Scale Autoscale Y from the shortcut menu By default autosc
361. tting ActiveX Properties section in this chapter for more information about setting ActiveX properties Use the Invoke Node to invoke the methods associated with the object For example you can display a Web page on the front panel by using an ActiveX container to access the Microsoft Web Browser object selecting the Navigate class of methods selecting the URL method and specifying the URL If you use the ActiveX container you do not have to have to wire the automation refnum control on the block diagram to the Automation Open function or close the reference to the object using the Automation Close function You can wire directly to the Invoke Node or Property Node because the ActiveX container embeds the calling application in Lab VIEW However if the ActiveX container includes properties or methods that return other automation refnum references you must close those other refnum controls Setting ActiveX Properties LabVIEW User Manual After you call or insert an ActiveX object or document you can set the properties associated with that object or document using the ActiveX Property Browser property pages and the Property Node ActiveX Property Browser Use the ActiveX Property Browser to view and set all the properties associated with an ActiveX object or document in an ActiveX container To access the ActiveX Property Browser right click the object or document in the container on the front panel and select Property Browser f
362. u aE EE EENE EAE E E EE a 8 6 Case Selector Values and Data Types sseeseseessseseersrrersrrsrrsrerrsrsee 8 7 Input and Output Tunnels 0 eee cee eeceeeceeceseseeeeaeeseeeaeeeeees 8 8 Using Case Structures for Error Handling 8 8 SEQUENCE Structures aaneren visustedsenvee arnss orae KEE NEE aS 8 8 Avoiding Overusing Sequence Structures seeseeseeereeeereerereerree 8 10 Event Driven Programming sssini iiiki eiciia iae iena ANEK aE eiai aaRS 8 11 What Are Events oissi sccssedsssccssscasesceseatescacaeeschesesbthssaub cous Ean AED eaa a VEs EE NT 8 11 Using Events in LabVIEW ipiis ci aiies asea aE EEE EEEE 8 12 Vent StruCtures iaeano iies er k Ee a EE a a EE aa 8 12 Configuring Event iosart a eaei eni o K asia e Ea 8 13 Filter and Notify Events sissioni sinisisi 8 13 Event Example sinirin ae E A EE EA AEA ETA 8 14 Chapter 9 Grouping Data Using Strings Arrays and Clusters SNAS ra E E a a O TE ES 9 1 Strings on theFront Panehscsoecieese e n eae as 9 2 Strine Display Ty pes er nonan a ki nea 9 2 ADIOS E N E E EOE E E 9 2 Programmatically Editing Strings e sesseeesseeeeeeeresrereerssrsresrsrerresesresrsresresest 9 3 Formatting Stinsen e E E et ew aes 9 4 Format SpecifierS ienn eee ee 9 4 Nu tmierics and SINE Seriene e e AA ERE EE EEE E E 9 5 Converting Data Types to XML woo eeceseeseeeecseeeseeseeeaeeseeesesseesseesees 9 5 Using XML Based Data Types eee eeeeceeseeseeeeseeeseeeeeeeeeseeeeees 9 6 LabVIEW XML
363. uilding Stand Alone Applications and Shared Libraries Select Tools Build Application or Shared Library DLL to use the Application Builder to create stand alone applications and installers or shared libraries DLLs for VIs Use shared libraries if you want to call the VIs in the shared library using text based programming languages Shared libraries are useful when you want to share the functionality of the VIs you build with text based programming language developers B Note The LabVIEW Professional Development System includes the Application Builder If you use the LabVIEW Base Package or Full Development System you can purchase the Application Builder separately LabVIEW User Manual 7 12 ni com Chapter 7 Creating Vis and SubVIs Use the tabs in the Build Application or Shared Library DLL dialog box to configure various settings for the application or shared library you want to build After you define these settings save them in a script so you can easily rebuild the application if necessary Users can run your application or use the shared library but they cannot edit or view the block diagrams Refer to the LabVIEW Application Builder Release Notes for more information about installing the Application Builder National Instruments Corporation 7 13 LabVIEW User Manual Part Il Building and Editing VIs This part describes LabVIEW features VIs and functions you can use to make your applications operate in spec
364. urves and surfaces A curve contains individual points on the graph each point having an x y and z coordinate The VI then connects these points with a line A curve is ideal for visualizing the path of a moving object such as the flight path of an airplane The 3D graphs use ActiveX technology and VIs that handle 3D representation You can set properties for the VIs located on the Functions Graphics amp Sound 3D Graph Properties palette to change behavior at run time including setting basic axes grid and projection properties A surface plot uses x y and z data to plot points on the graph The surface plot then connects these points forming a three dimensional surface view of the data For example you could use a surface plot for terrain mapping When you select a 3D graph LabVIEW places an ActiveX Container on the front panel that contains a 3D graph control LabVIEW also places a reference to the 3D graph control on the block diagram LabVIEW wires this reference to one of the three 3D Graph VIs Waveform Data Type LabVIEW User Manual The waveform data type is a cluster of elements that carries the data start time and At of a waveform You can create waveforms using the Build Waveform function located on the Functions Waveform palette Many of the VIs and functions you use to acquire or analyze waveforms accept and return the waveform data type by default When you wire a waveform data type to a waveform graph or
365. us in Run Mode When a VI is running or is in run mode all front panel objects have an abridged set of shortcut menu items Use the abridged shortcut menu items to cut copy or paste the contents of the object to set the object to its default value or to read the description of the object Some of the more complex controls have additional options For example the array shortcut menu includes items to copy a range of values or go to the last element of the array National Instruments Corporation 3 3 LabVIEW User Manual Chapter 3 LabVIEW Environment Toolbar Use the toolbar buttons to run and edit a VI When you run a VI buttons appear on the toolbar that you can use to debug the VI Customizing Your Work Environment You can change the way the Controls and Functions palettes appear and you can use the Options dialog box to set other work environment options Customizing the Controls and Functions Palettes LabVIEW User Manual You can customize the Controls and Functions palettes in the following ways e Add VIs and controls to the palettes e Set up different views for different users hiding some VIs and functions to make LabVIEW easier to use for one user while providing the full palettes for another user e Rearrange the built in palettes to make the VIs and functions you use frequently more accessible e Convert a set of ActiveX controls into custom controls and add them to the palettes e Add toolsets t
366. vide up to date contact information support phone numbers e mail addresses and current events If you have searched the technical support resources on our Web site and still cannot find the answers you need contact your local office or National Instruments corporate Phone numbers for our worldwide offices are listed at the front of this manual LabVIEW User Manual E 2 ni com Glossary Prefix Meaning Value m milli 10 3 k kilo 103 M mega 106 Numbers Symbols A Delta difference Ax denotes the value by which x changes from one index to the next T Pi oo Infinity 1D One dimensional 2D Two dimensional A A absolute coordinates absolute path AC active window application software National Instruments Corporation G 1 Amperes Picture coordinates relative to the origin 0 0 of the picture indicator File or directory path that describes the location relative to the top level of the file system Alternating current Window that is currently set to accept user input usually the frontmost window The titlebar of an active window is highlighted Make a window active by clicking it or by selecting it from the Windows menu Application created using the LabVIEW Development System and executed in the LabVIEW Run Time System environment LabVIEW User Manual Glossary array artificial data dependency ASCII auto indexing autoscaling block diagra
367. w the data type for their individual input or output terminals until you wire objects to these terminals When you wire them these terminals look similar to the data types of the corresponding front panel control or indicator terminals Polymorphism for Comparison Functions LabVIEW User Manual The functions Equal Not Equal and Select take inputs of any type as long as the inputs are the same type The functions Greater or Equal Less or Equal Less Greater Max amp Min and In Range take inputs of any type except complex path or refnum as long as the inputs are the same type You can compare numbers strings Booleans arrays of strings clusters of numbers clusters of strings and so on However you cannot compare a number to a string or a string to a Boolean and so on The functions that compare values to zero accept numeric scalars clusters and arrays of numbers These functions output Boolean values in the same data structure as the input The Not A Number Path Refnum function accepts the same input types as functions that compare values to zero This function also accepts paths and refnums Not A Number Path Refnum outputs Boolean values in the same data structure as the input The functions Decimal Digit Hex Digit Octal Digit Printable and White Space accept a scalar string or number input clusters of strings or non complex numbers arrays of strings or non complex numbers and so on The output co
368. with the Array to Spreadsheet String function and specify a format and a delimiter Use the String functions located on the Functions String palette to perform the following tasks e Concatenate two or more strings e Extract a subset of strings from a string e Convert data into strings e Formata string for use in a word processing or spreadsheet application Use the File I O VIs and functions located on the Functions File I O palette to save strings to text and spreadsheet files Format Specifiers In many cases you must enter one or more format specifiers in the format string parameter of a String function to format a string A format specifier code that indicates how to convert data to or from a string LabVIEW uses conversion codes to determine the textual format of the parameter For example a format specifier of x converts a hex integer to or from a string The Format Into String and Scan From String functions can use multiple format specifiers in the format string parameter one for each input or output to the expandable function The Array To Spreadsheet String and Spreadsheet String To Array functions use only one format specifier in the format string parameter because these functions have only one input to convert LabVIEW treats any extra specifiers you insert into these functions as literal strings with no special meaning 9 4 ni com Chapter 9 Grouping Data Using Strings Arrays and Clusters Numerics and Strin
369. y iteration of the loop Therefore auto indexed output arrays are always equal in size to the number of iterations Right click the tunnel at the loop border and select Enable Indexing or Disable Indexing from the shortcut menu to enable or disable auto indexing Auto indexing for While Loops is disabled by default The loop indexes scalar elements from 1D arrays 1D arrays from 2D arrays and so on The opposite occurs at output tunnels Scalar elements accumulate sequentially into 1D arrays 1D arrays accumulate into 2D arrays and so on Auto Indexing to Set the For Loop Count If you enable auto indexing on an array wired to a For Loop input terminal LabVIEW sets the count terminal to the array size so you do not need to wire the count terminal Because you can use For Loops to process arrays an element at a time LabVIEW enables auto indexing by default for every array you wire to a For Loop Disable auto indexing if you do not need to process arrays an element at a time If you enable auto indexing for more than one tunnel or if you wire the count terminal the count becomes the smaller of the choices For example if two auto indexed arrays enter the loop with 10 and 20 elements respectively and you wire a value of 15 to the count terminal the loop executes 10 times and the loop indexes only the first 10 elements of the second array If you plot data from two sources on one graph and you want to plot the first 100 elements wire 1
370. you can read the original blocks of data back as a record without having to read all records that precede it in the file Random access is fast and easy with datalog files because all you need to access the record is the record number LabVIEW sequentially assigns the record number to each record when it creates the datalog file You can access datalog files from the front panel and from the block diagram Refer to the Logging Front Panel Data section of this chapter for more information about accessing datalog files from the front panel LabVIEW writes a record to a datalog file each time the associated VI runs You cannot overwrite a record after LabVIEW writes it to a datalog file When you read a datalog file you can read one or more records at a time Refer to the examples file datalog 11b for examples of reading and writing datalog files 13 4 ni com Chapter 13 File 1 0 Using High Level File 1 0 Vis Use the high level File I O VIs located on the top row of the Functions File I O palette to perform common I O operations such as writing to or reading from the following types of data e Characters to or from text files e Lines from text files e 1Dor 2D arrays of single precision numerics to or from spreadsheet text files e 1Dor2D arrays of single precision numerics or signed 16 bit integers to or from binary files You can save time and programming effort by using the high level VIs to write to and read from files T
371. you work with variables remember the following points National Instruments Corporation There is no limit to the number of variables or equations in a Formula Node No two inputs and no two outputs can have the same name but an output can have the same name as an input Declare an input variable by right clicking the Formula Node border and selecting Add Input from the shortcut menu You cannot declare input variables inside the Formula Node Declare an output variable by right clicking the Formula Node border and selecting Add Output from the shortcut menu The output variable name must match either an input variable name or the name of a variable you declare inside the Formula Node You can change whether a variable is an input or an output by right clicking it and selecting Change to Input or Change to Output from the shortcut menu You can declare and use a variable inside the Formula Node without relating it to an input or output wire You must wire all input terminals Variables can be floating point numeric scalars whose precision depends on the configuration of your computer You also can use integers and arrays of numerics for variables Variables cannot have units 20 3 LabVIEW User Manual Chapter 20 Formulas and Equations Expression Nodes Use Expression Nodes to calculate expressions or equations that contain a single variable Expression Nodes are useful when an equation has only one variable bu

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