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SCXI-1540 User Manual

1. ZONAS 1ojelioso t it c a S PN 19 ueg ssedmoq 4 XJ e qeueA a a uone npouie ien AS AS OONAS pue 0x3 K 10101080 ay M oxa UON YMS 1 f fT L sng Jexejdniniw i a 5 EN 8 un 8 t 1exejdninig HOW e Boreuy 1 gt ule duy T SHON Y ssedmo7 VU ejgeueA ua a Mon t er indu Figure 4 3 SCXI 1540 Block Diagram SCXI 1540 User Manual 4 5 National Instruments Corporation Chapter 4 Theory of Operation The LVDT returns a signal whose phase and amplitude is related to the position of the movable core The return signal connects across the CH and CH terminals on the front signal connector In normal operation this signal passes through the input selection switch to the differential amplifier where the common mode signal on the input wires is rejected The signal then passes to a variable gain stage that is set to a gain that best covers the expected signal r
2. sse 1 5 Installing SCXI Using NI DAQmx in Software 1 5 Manually Adding Modules in NI DAQmx 1 5 Installing SCXI Using Traditional NI DAQ Legacy in Software 1 5 Manually Adding Modules in Traditional NI DAQ Legacy 1 5 Verifying and Self Testing the Installation 1 5 Troubleshooting the Self Test Verification essere 1 6 Troubleshooting in NI DAQmx 1 6 Troubleshooting in Traditional NI DAQ Legacy 1 7 Chapter 2 Connecting Signals Connecting to LVDTs 2 1 Synchronizing Channels teinte le tete iecit tds 2 3 Connecting to ResolVers eee tette tee t ger pete Reg eee 2 4 Pin erp EE PE ER e ER ES 2 5 Rear Signal Connectors uinea ee e e Ee e 2 7 Chapter 3 Configuring and Testing Common Software Configurable Settings eee 3 1 Gain Input Range daa tte ite ott epe de 3 1 Excitation Eevel nene onem eoe 3 2 Excitation Frequency tette re Re e e Pe Pa eus 3 2 Excitation Source eet tt ditta e HS e e ci Eia 3 2 Wire Mode cr UR pa eret e er 3 2 External Synchronization sistini ii raira emere 3 3 National Instruments Corporation SCXI 1540 User Manual Contents Configurable Settings in MAX sse eene enne 3 3 NEDAQmX iuc the ei p adn npe dette 3 3 Creating an LVDT RVDT Global Channel or Task in N
3. seen 5 24 Using Software for Multiplexed Scanning esee 5 24 LabVIEW and the SCXI Channel String 5 24 LabVIEW the Virtual Channel String sss 5 26 Performing a Multiplexed Scan essere 5 26 C and Low Level DAQ Functions 5 277 Traditional NI DAQ Legacy CVI Examples eee 5 28 Traditional NI DAQ Legacy Measurement Studio Examples 5 28 Calibration trt p duh I ee t had E 5 28 Calibration Procedures 2 rp ei eee eia 5 28 Calibration Using LabVIEW or a C Based 5 29 Appendix A Specifications Appendix B Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later Appendix C Removing the SCXI 1540 Appendix D Common Questions National Instruments Corporation vii SCXI 1540 User Manual Contents Glossary Index Figures Figure 2 1 4 Wire Connection to or see 2 1 Figure 2 2 5 Wire Connection to an 2 2 Figure 2 3 Multiple Channel Synchronization eee 2 3 Figure 2 4 Resolver Connection 2 4 Figure4 1 Cut Away View of an LVDT sese ene 4 1 Figure 4 2 LVDT Core Locations with Resulting Induced Voltage and Phase 4 3 Figure 4 3 SCXI 1540 Block Diagram eese 4 5 Figure 5
4. eee 5 4 Configuring Channel Properties sese 5 5 Acquiring Analyzing and Presenting see 5 7 Completing the Application sese 5 7 Developing an Application Using LabVIEW 5 7 Using a DAQmx Channel Property Node in LabVIEW 5 9 Specifying Channel Strings in NI DAQmx eee 5 10 Text Based e etre eren eres 5 11 Programmable NI DAQmx Properties 5 14 Developing Your Application in Traditional NI DAQ 5 14 Traditional NI DAQ Legacy in LabVIEW 5 14 Typical Program eee mette tmr stent 5 16 SCXI 1540 User Manual vi ni com Contents Configure the SCXI 1540 Settings Using Traditional NI DAQ Legacy In LabVIEW AAR ETTE RE eie b e E 5 17 Configure Start Acquisition and Take Readings Using Traditional NI DAQ Legacy in LabVIEW 5 19 Analyze and Display Using Traditional NI DAQ Legacy in LabVIEW 5 19 Traditional NI DAQ Legacy in Text Based ADES 5 19 Configuring System Settings Using Traditional NI DAQ Legacy C API 5 20 Configure Module Settings Using Traditional NI DAQ Legacy C API 5 22 Perform Acquisition Using Traditional NI DAQ Legacy C API 5 23 Perform Scaling Analysis and Display eee 5 23 Other Application Documentation and Material
5. You should select the frequency closest to that specified by the sensor manufacturer The sensitivity of the sensor can vary considerably from the specified value if another excitation frequency is used Select internal or external based on the source of the excitation External is required for the slave channel when using a resolver Refer to Chapter 5 Using the SCXI 1540 for information about programming a resolver 3 Note The SCXI 1540 is not intended for use with external excitation sources that are not supplied directly by the SCXI 1540 Wire Mode SCXI 1540 User Manual Select 4 wire for 4 wire connections and 5 wire for 5 wire connections Refer to the Connecting to LVDTs and RVDTs section of Chapter 2 Connecting Signals for the advantages and disadvantages of each connection method 3 2 ni com Chapter 3 Configuring and Testing External Synchronization Channels that are to be synchronized to the frequency and level of another channel must have external synchronization enabled You must also make wire connection between the SYNC terminal of the slaved channel and the EX terminal of the master channel Refer to Figure 2 3 Multiple Channel Synchronization Configurable Settings in MAX iyi Note If you are not using an NI ADE using an NI ADE prior to version 7 0 or are using an unlicensed copy of an NI ADE additional dialog boxes from the NI License Manager appear allowing you to create a task or global channe
6. Configure Module Settings Using Traditional NI DAQ Legacy C API After configuring the hardware for acquisition you must load the various channel attributes such as filter gain and excitation appropriate for your application explicitly using the NI DAQ function calls shown in Table 5 5 For more information regarding each setting refer to the Traditional NI DAQ Legacy C Function Reference Help installed by default in Start Programs National Instruments NI DAQ Table 5 5 NI DAQ Functions Used to Configure SCXI 1540 Channel Significant Possible Setting NI DAQ Function to Use Parameters Parameters Values Connection SCXI Configure Connection 116 0 Four wire Type connectionType connection Five wire connection 2 Disable external synchronization 3 Enable external synchronization Excitation SCXI Set Excitation 16 0 voltage Voltage excitationType specified in units of type of excitation V cms 19560 1 0 3 0 32 excitationValue new value for the specified excitation parameter Excitation SCXI_Set_Excitation 16 1 AC frequency Voltage excitationType specified in units of type of excitation Hz 985 2500 3300 5000 32 10000 excitationValue new value for the specified excitation parameter SCXI 1540 User Manual 5 22 ni com Chapter 5 Using the SCXI 1540 Perform Acquisition Using Traditional NI DAQ Legacy C API There are several NI DAQ functions you can
7. specifier is optional and causes the gains on the module and E Series DAQ device to be automatically set to fit the input limits parameter When this specifier is omitted the default gain on the E Series DAQ device usually the lowest gain is used but the SCXI 1540 gain is adjusted to fit the input limits The last parameter channels is the list of channels that are scanned for module z It can have several formats e scy mdz n where n is a single input channel e scy mdz n1 n2 where n1 and n2 represent a sequential list of input channels inclusive scy mdz nl n2 n3 n4 nl n5 n2 where n1 n2 and n5 represent single channels not necessarily sequential and n3 and represent the endpoints of a sequential list of channels inclusive In this case channels n4 and n2 have explicitly been repeated in the channel list Note Repeating channels or having channels out of sequence in a scan list is not supported on all SCXI modules Please refer to the manual of each module for information on this feature National Instruments Corporation 5 25 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 LabVIEW and the Virtual Channel String For LabVIEW and Visual Basic 6 the channel string can also contain virtual channels For the SCXI 1540 these virtual channels are analog input channels you create that have custom names that perform all error correction and scaling without addi
8. Secondary Primary Secondary A x E Output Signal Figure 4 1 Cut Away View of an LVDT The primary winding located at center is excited with a sine wave voltage The resulting magnetic field is coupled through the movable core into the secondary windings located on either side of the primary With the core at center both secondaries have the same induced voltage With the series connection and polarity shown the resulting output signal is zero If the core moves to the left the left secondary is more strongly coupled to the primary than the right secondary resulting in a stronger induced voltage in the left secondary and an output signal that is in phase with the primary National Instruments Corporation 4 1 SCXI 1540 User Manual Chapter 4 Theory of Operation excitation voltage The more the core moves off center the stronger the imbalance and the greater the output signal Moving the core to the left of center results in the same behavior but with the output signal out of phase with the excitation signal Figure 4 2 shows these core locations and the resulting induced voltage and phase SCXI 1540 User Manual 4 2 ni com Chapter 4 Theory of Operation Secondary Primary Secondary Y FN x t n pee Output Signal Secondary P
9. measuring absolute angular displacement whose measurement range is typically between 30 and x70 of rotation seconds samples per second used to express the rate at which a E M Series DAQ device samples an analog signal one or more analog samples taken at the same time or nearly the same time Typically the number of input samples in a scan is equal to the number of channels in the input group For example one scan acquires one new sample from every analog input channel in the group SCXI 1540 User Manual Glossary scan rate SCANCLK SCXI SCXIbus sensitivity SERDATOUT signal conditioning SYNC system noise T Traditional NI DAQ Legacy UL SCXI 1540 User Manual the number of scans a system takes during a given time period usually expressed in scans per second For example a scan rate of 10 Hz means sampling each channel 10 times per second scan clock signal used to increment to the next channel after each E M Series DAQ device analog to digital conversion Signal Conditioning eXtensions for Instrumentation the National Instruments product line for conditioning low level signals within an external chassis near sensors so only high level signals are sent to E M Series DAQ devices in the noisy PC environment located in the rear of an SCXI chassis the SCXIbus is the backplane that connects modules in the same chassis to each other for an LVDT or RVDT the ratio of output voltage change to inp
10. sss 6 Vims Measurement Category I Channel to channel 6 Vims Measurement Category I UN Caution Do not use for measurements within Measurement Categories II or IV Environmental Operating 0 to 50 C Storage temperature 20 to 70 C Humudity 2 edi 10 to 90 RH noncondensing National Instruments Corporation A 5 SCXI 1540 User Manual Appendix A Specifications Maximum altitude esses 2 000 m Pollution Degree indoor use only esses 2 Safety This product is designed to meet the requirements of the following standards of safety for electrical equipment for measurement control and laboratory use e TEC 61010 1 EN 61010 1 e UL 61010 1 61010 1 iyi Note For UL and other safety certifications refer to the product label or visit ni com certification search by model number or product line and click the appropriate link in the Certification column Electromagnetic Compatibility This product is designed to meet the requirements of the following standards of EMC for electrical equipment for measurement control and laboratory use e EN 61326 EMC requirements Minimum Immunity e EN 55011 Emissions Group 1 Class C Tick ICES and FCC Part 15 Emissions Class 3 Note For EMC compliance operate this device with shielded cables CE
11. Compliance This product meets the essential requirements of applicable European Directives as amended for CE marking as follows e 73 23 EEC Low Voltage Directive safety e 89 336 EEC Electromagnetic Compatibility Directive EMC iyi Note Refer to the Declaration of Conformity DoC for this product for any additional regulatory compliance information To obtain the DoC for this product visit ni com certification search by model number or product line and click the appropriate link in the Certification column SCXI 1540 User Manual A 6 ni com Appendix A Specifications Waste Electrical and Electronic Equipment WEEE 9 EU Customers At the end of their life cycle all products must be sent to WEEE recycling center For more information about WEEE recycling centers and National Instruments WEEE initiatives visit ni com environment weee htm National Instruments Corporation A 7 SCXI 1540 User Manual Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later 3 Note This appendix is not applicable if you use the virtual channels to configure and measure the SCXI channels Virtual channels are configured using MAX If you use virtual channels you address the SCXI channels by specifying the channel name s in the channel string input When using LabVIEW and Visual Basic 6 the SCXI channel string determines which SCXI channels are scanned and the scanning sequence The SCXI channel string allows
12. EIE RR Re excitation setting in volts rms x sensor sensitivity For example if you are working with an LVDT with a manufacturer specified sensitivity of 1 2 mV V mil or equivalently 0 0012 V V mil and the excitation level of the corresponding SCXI 1540 channel is 3 Vms the conversion formula is 1540 data in volts rms 3 V ms X 0 0012 volts per volt per mil x 1000 mils per inch _ SCXI 1540 data in volts rms i 3 6 volts per inch SCXI 1540 data in volts rms x 0 278 inch per volt Converting Resolver Data to Angular Position Converting resolver data to angular position is accomplished by simply passing the data from the two channels to a four quadrant arctangent function such as the LabVIEW function Inverse Tangent 2 Input This function is on the Trigonometric subpalette To access this function select Function Numeric Trigonometric 4 8 ni com Chapter 4 Theory of Operation Theory of Parallel Mode Operation Parallel mode is ideal for high speed acquisitions In parallel mode the eight conditioned analog output signals at the rear signal connector of the SCXI 1540 shown in Figure 4 3 are connected directly to the eight analog input channels on the E M Series DAQ device When the SCXI 1540 operates in parallel mode the E M Series DAQ device performs multiplexed scans of the SCXI 1540 parallel outputs The SCXI 1540 module does not multiplex the channels Traditional NI DAQ Legacy
13. 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 information 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 owne
14. User Manual LabVIEW is a graphical programming environment for test and measurement application development with built in easy to use tools for data acquisition analysis and display Traditional NI DAQ Legacy provides several standard data acquisition subVIs as well as subVIs specifically for use with the SCXI 1540 For applications using Traditional NI DAQ Legacy in LabVIEW there are two typical methods of addressing SCXI 1540 channels virtual channels specifically LVDT RVDT virtual channels and SCXI channel 5 14 ni com Chapter 5 Using the SCXI 1540 strings Depending on the needs of your application you choose one of these channel addressing methods to use in your LabVIEW application The LVDT RVDT virtual channel provides scaling for LVDT RVDTS and allows you to select any name for the SCXI 1540 LVDT RVDT channel that you choose without additional code When you use virtual channels the maximum number of channels per E Series DAQ device is 512 in multichassis systems NI recommends using the LVDT RVDT virtual channel for ease of use Refer to Appendix B Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later for more information on how to create a LVDT RVDT virtual channel The SCXI channel string allows you to combine large numbers of channels into fewer scan list entries and to measure the signal voltage level directly for custom scaling in your application NI recommends using SCXI channel strings fo
15. call functions from the DAQ driver dynamically linked library dll The C and Low Level DAQ Functions section outlines the steps for programming with the low level DAQ function calls If you are using LabWindows CVI or Measurement Studio you also can write advanced applications using the same low level DAQ functions guidelines Configuring System Settings Using Traditional NI DAQ Legacy C SCXI 1540 User Manual Start the configuration of the acquisition by ensuring that the SCXI 1540 module and SCXI chassis are in their default states and that the driver software configuration matches the states the actual physical hardware configuration After setting the hardware and software to the defaults of the module s you can configure any module settings that vary from the default configuration settings You also should configure the acquisition parameters using the functions in Table 5 4 For additional information such as the function prototypes parameters and usage instructions for each function refer to the Traditional NI DAQ Legacy C Function Reference Help installed by default in Start Programs National Instruments NI DAQ 5 20 ni com Chapter 5 Using the SCXI 1540 Table 5 4 Configuration Functions Function Description SCXI Reset Resets the hardware such as the specified module to its default state You also can use SCXI Reset to reset the SCXI chassis Slot 0 scanning circuitry or reset the entire chassis
16. data acquisition application You can find the intermediate data acquisition Traditional NI DAQ Legacy functions in the function subpalettes Data Acquisition Analog Input NI recommends using the intermediate analog input functions for most SCXI 1540 applications For more information about using the intermediate data acquisition Traditional NI DAQ Legacy functions refer to the LabVIEW Measurements Manual You also can use the LabVIEW Help for more detailed information about the various inputs and outputs of these functions Analyze and Display Using Traditional NI DAQ Legacy in LabVIEW In LabVIEW you can easily analyze SCXI 1540 measurements with a variety of powerful analysis functions that you can find in the function subpalettes Analyze Waveform Conditioning and Analyze Signal Processing You can perform post acquisition processing such as waveform comparisons harmonic analysis and digital filtering For more information about these VIs refer to the LabVIEW Analysis Concepts manual You also can use the LabVIEW Help for more detailed information about how to use the analysis VIs In LabVIEW you also can easily display SCXI 1540 measurements with a variety of graphical waveform graphs numeric slides gauges and other indicators You can find useful graphical controls and indicators for user interaction with your application in the controls subpalettes For more information about these VIs refer to the LabVIEW User Manual
17. driver software can only control the SCXI 1540 module in multiplexed mode NI DAQmx can operate the SCXI 1540 in both multiplexed and parallel mode In parallel mode SCXI 1540 channels 0 through 7 conditioned outputs are passed directly to E M Series DAQ device channels 0 through 7 The E M Series DAQ device channels should be configured for differential input mode Parallel mode operation acquisition rates have limitations that are determined based on the E M Series DAQ device you are using The maximum sampling rate is determined by the maximum sample rate of the E M Series DAQ device The 333 kHz maximum SCXI multiplexing rate is not a limitation in parallel mode operation Therefore if the E M Series DAQ device can sample more quickly than 333 kHz the SCXI 1540 configured for parallel mode operation is not the limiting factor National Instruments Corporation 4 9 SCXI 1540 User Manual Using the SCXI 1540 This chapter makes suggestions for developing your application and provides basic information regarding calibration Developing Your Application in NI DAQmx Note If you are not using an ADE using an NI ADE prior to version 7 0 are using an unlicensed copy of an NI ADE additional dialog boxes from the NI License Manager appear allowing you to create a task or global channel in unlicensed mode These messages continue to appear until you install version 7 0 or later of an NI ADE This section describes how
18. electrical signals from sensors transducers and test probes or fixtures and processing the measurement data using a computer 2 collecting and measuring the same kinds of electrical signals with A D and or DIO boards plugged into a computer and possibly generating control signals with D A and or DIO boards in the same computer a data acquisition device Examples are DIO and E M Series MIO data acquisition devices direct current digital ground signal Deutsche Industrie Norme German Industrial Standard digital input output digital multimeter electrically erasable programmable read only memory ROM that can be erased with an electrical signal and reprogrammed Some SCXI modules contain an EEPROM to store measurement correction coefficients electromagnetic compliance G 2 ni com EMI EX EX gain gain accuracy gain error I O in input impedance LPF LVDT National Instruments Corporation G 3 Glossary electromagnetic interference a negative excitation output terminal a positive excitation output terminal the factor by which a signal is amplified sometimes expressed in decibels a measure of deviation of the gain of an amplifier from the ideal gain See gain accuracy hertz cycles per second of a periodic signal the unit of measure for frequency input output the transfer of data to from a computer system involving communications channels operator interface devices and or data ac
19. for External Synchronization a IGNEO o EX1 Figure 2 4 Resolver Connection SCXI 1540 User Manual 2 4 ni com Chapter 2 Connecting Signals Pin Assignment The pin assignment for the SCXI 1540 front signal connector is shown in Table 2 1 Notice that the positive input terminal for each channel is in Column C and the negative input terminal is in Column B The pins labeled RSVD and P1 P7 are reserved Do not make any connections to these pins UN Caution Do not make signal connections to pins in column A of Table 2 1 National Instruments Corporation 2 5 SCXI 1540 User Manual Chapter 2 Connecting Signals Table 2 1 Front Signal Pin Assignments Front Connector Diagram Pin Number Column A Column B Column C 32 RSVD CH0 CH0 Column 31 RSVD GND SYNCO A B C 30 RSVD EX 0 0 32 29 RSVD GND PO 31 28 RSVD CH1 CH 1 30 29 o o 21 RSVD GND SYNCI 28 26 RSVD EX1 EX14 27 o o 25 RSVD GND 26 24 RSVD CH2 CH24 25 23 RSVD GND SYNC2 24 23 o o 22 RSVD EX2 2 22 o 21 RSVD GND P2 21 o0 20 RSVD CH3 20 19 RSVD GND SYNC3 19 fe e cue 18 RSVD EX3 3 177 o o 17 RSVD GND P3 16 o o 16 RSVD CH4 Puppe ee se 15 RSVD
20. md3 0 7 b Select internal calibration as the calibration operation you are going to perform c Select the Default EEPROM load area as the area you want to update If you are using a C based ADE use the following procedure 1 Make sure the E M Series DAQ device or DMM you are using has a valid calibration and meets the accuracy specifications for your application 2 Use the NI DAQ function SCXI Calibrate a Enter E M Series DAQ device DAQ channel and module slot You need not enter a channel number since SCXI_Calibrate automatically calibrates all channels of the SCXI 1540 b Select internal calibration 0 as the operation you are going to perform c Select the load area 1 as the EEPROM area you want to update The SCXI 1540 takes a few seconds to perform the calibration After completion your module has new calibration constants stored for all channels gains and excitation settings National Instruments Corporation 5 29 SCXI 1540 User Manual Specifications This appendix lists the specifications for the SCXI 1540 modules These specifications are typical at 25 C unless otherwise noted General Specifications Table A 1 Input Range Gain and Required E M Series DAQ Device Input Limits E M Series DAQ Input Range Gain Setting Device Input Limits Vims VDC out V ms in V 6 0 0 8 5 0 5 5 0 9 5 0 5 0 1 0 5 0 4 5 1 1 5 0 4
21. scaling LVDT and RVDT data 4 8 steps 5 26 using software 5 24 SCXI 1540 D 3 NI DAQ software and MacOS D 3 functions used to configure SCXI 1540 table 5 27 version required D 1 P physical specifications A 5 pin assignments 2 5 front signal connector table 2 6 power requirements A 4 power up state of SCXI 1540 D 3 PXI SCXI combination chassis 1 4 ni com 0 questions and answers D 1 R random scanning 4 6 rear signal connector 2 7 removing the SCXI 1540 from Measurement amp Automation Explorer C 1 resolver connection figure 2 4 resolvers 4 1 converting resolver data to angular position 4 8 defined 4 4 signal connections 2 4 rotary variable differential transformers 4 1 defined 4 4 scaling data in multiplexed scanning 4 8 signal connections 4 wire figure 2 1 5 wire figure 2 2 S SCXI channel string See also multiplexed scanning defined 5 24 LabVIEW channel scanning 5 24 SCXI chassis connecting SCXI 1540 to DAQ device 1 4 SCXI 1540 accessories for connecting signals D 3 block diagram figure 4 5 cabling restrictions with plug in E M Series DAQ device D 3 calibration 5 28 common questions D 1 National Instruments Corporation F3 Index configuring with NI DAQ functions table 5 27 connectors rear signal connector 2 7 digital signals table D 2 LVDTs RVDTs and resolvers 4 1 MacOS D 3 multiplexed scanning D 3 steps 5 26 overvi
22. the SCXI 1540 This chapter introduces the SCXI 1540 module and explains how to install the software and hardware S Note Descriptions in this chapter explicitly refer to the first channel channel 0 but these descriptions also are applicable to the remaining seven channels This section provides an introduction to the SCXI 1540 module and to linear variable differential transformers LVDTs rotary variable differential transformers and resolvers The SCXI 1540 module is an eight channel module for interfacing with industry standard LVDTs RVDTs and resolvers It can accommodate 4 wire or 5 wire connection to an LVDT and can synchronize any number of channels to a common frequency You can set the excitation level at 1 Vims 0r3 Vins at a frequency of 2 5 3 3 5 or 10 KHz You can set the gain over the range 0 8 to 25 to handle a wide range of LVDT sensitivities Gain level frequency and wire mode are set on a per channel basis without the use of jumpers The SCXI 1540 is configured using Measurement amp Automation Explorer MAX or through function calls to NI DAQ What You Need to Get Started To set up and use the SCXI 1540 you need the following Q Hardware SCXI 1540 module of following terminal blocks e SCXI 1315 SCXI 1310 e TBX 96 SCXIchassis or PXI SCXI combination chassis National Instruments Corporation 1 1 SCXI 1540 User Manual Chapter 1 About the SC
23. the property add a control constant or indicator To add another property to the property node right click an existing property and left click Add Element To change the new property left click it and select the property you wish to define Note Refer to the LabVIEW Help for information about property nodes and specific NI DAQmx properties Text Based ADEs You can use text based ADEs such as LabWindows CVI Measurement Studio Visual Basic 6 and to create code for using the SCXI 1540 National Instruments Corporation 5 11 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 LabWindows CVI LabWindows CVI works with the DAQ Assistant in MAX to generate code for an LVDT RVDT task You can then use the appropriate function call to modify the task To create a configurable channel or task in LabWindows CVI complete the following steps 1 Launch LabWindows CVI 2 Open a new or existing project 3 From the menu bar select Tools Create Edit DAQmx Tasks 4 Choose Create New Task In MAX or Create New Task In Project to load the DAQ Assistant 5 The DAQ Assistant creates the code for the task based on the parameters you define in MAX and the device defaults To change a property of the channel programmatically use the DAQmxSetChanAttribute function 3 Note Refer to the NI LabWindows CVI Help for more information on creating NI DAQmx tasks in LabWindows CVI and NI DAQmx property information SCXI 1
24. use to take measurements Usually in SCXI the preference is to take multiple samples from multiple channels using the SCAN function SCAN Op performs a synchronous multiple channel scanned data acquisition operation SCAN Op does not return until Traditional NI DAQ Legacy acquires all the data or an acquisition error occurs For this reason it is sometimes useful to use SCAN Op in conjunction with the function Timeout Config which establishes a timeout limit synchronous functions to ensure that these functions eventually return control to your application After acquiring data using SCAN Op the resultant data is not organized by channel so you should demultiplex the data using SCAN Demux SCAN Demux rearranges or demultiplexes data acquired by a SCAN Op into row major order meaning each row of the array holding the data corresponds to a scanned channel for easier access by C applications BASIC applications need not call SCAN Demux to rearrange two dimensional arrays since these arrays are accessed in column major order For more information regarding each acquisition function refer to the Traditional NI DAQ Legacy Function Reference Help installed by default in Start Programs National Instruments NI DAQ Sy Note synchronize multiple channels you must make the connections shown in Figure 2 4 and configure the slaved channels as externally synchronized Do this through MAX or by using the NI DAQ function SCXI Configure Conn
25. 0 1 25 5 0 3 5 1 4 5 0 3 0 1 6 5 0 27 1 8 5 0 2 5 2 0 5 0 2 2 2 2 5 0 2 0 2 5 5 0 1 7 2 8 5 0 1 5 3 2 5 0 1 35 3 6 5 0 1 25 4 0 5 0 1 10 4 5 5 0 National Instruments Corporation A 1 SCXI 1540 User Manual Appendix A Specifications Table A 1 Input Range Gain and Required E M Series DAQ Device Input Limits Continued E M Series DAQ Input Range Gain Setting Device Input Limits Vims VDC out V ms in V 1 00 5 0 5 0 0 85 5 6 5 0 0 75 6 3 5 0 0 70 7 0 5 0 0 62 8 0 5 0 0 55 9 0 5 0 0 50 10 0 5 0 0 45 11 0 5 0 0 40 12 5 5 0 0 35 14 0 5 0 0 31 16 0 5 0 0 27 18 0 5 0 0 25 20 0 5 0 0 22 22 0 5 0 0 20 25 0 5 0 0 10 25 0 2 5 0 05 25 0 1 0 Input impedance sess 100 2 Frequency response 250 Hz LPF 4 pole Butterworth Input connections sees 4 or 5 wire Synchronization s s Internal or external 1 When using external synchronization the SCXI 1540 only supports input excitation sources that are supplied by the SCXI 1540 SCXI 1540 User Manual A 2 ni com Absolute Accuracy Appendix A Specifications Residual ripple and noise 0 196 peak of full scale Nonlinearity 0 1906 of full scale max 0 05 of full scale typ Output range iet ete 5 0 V Output offset drift eee 70 uV C
26. 1 Typical Program Flowchart for Channels 5 2 Figure 5 2 Typical Program Flowchart for Resolver Channels 5 3 Figure 5 3 LabVIEW Channel Property Node with AC Excitation at 1 Volt RMS and AC Excit Frequency at 2500 2 5 10 Figure 5 4 Typical SCXI 1540 Program Flow with Traditional 5 16 Figure 5 5 Using the AI Parameter VI to Set Up the 8 1 1540 5 18 Figure 1 SCXI 1540 Dimensions eene ene A 5 Figure C 1 Removing the 5 154 C 2 Tables Table 2 1 Front Signal Pin Assignments 2 6 Table 2 2 Rear Signal Pin Assignments essere 2 8 Table 5 1 NI DAQmx Properties esses eene ennemi 5 5 Table 5 2 Programming a Task in LabVIEW 5 8 Table 5 3 Settings for Configuring the SCXI 1540 Through the AI Parameter 5 17 Table 5 4 Configuration Functions 5 21 Table 5 5 NI DAQ Functions Used to Configure SCXI 1540 5 22 Table 5 6 NI DAQ Functions Used to Configure SCXI 1540 5 27 Table A 1 Input Range Gain and Required E M Series DAQ Device Input Tinits A 1 Table A 2 Absolute System Accuracy A 4 Table D 1 Digital Signals on SCXI 1540 sese D 2 SCXI 1540 User Manual viii ni com About
27. 2 front signal connector pin assignments figure 2 6 SCXI 1540 User Manual Index G gain setting 3 1 installation connecting to DAQ device for multiplexed scanning in PXI SCXI combination chassis 1 4 in SCXI chassis 1 4 into SCXI chassis 1 4 installing and configuring the SCXI 1540 1 1 L LabVIEW calibration procedure 5 29 changing configuration settings D 2 input limits D 2 SCXI channel string 5 24 synchronization D 4 virtual channel string 5 26 low level DAQ functions in multiplexed scanning 5 27 LVDTs linear variable differential transformers 4 1 core locations with resulting induced voltage and phase figure 4 3 cut away view figure 4 1 description 4 1 scaling data in multiplexed scanning 4 8 signal connections 4 wire figure 2 1 5 wire figure 2 2 use of 4 4 Measurement amp Automation Explorer removing the SCXI 1540 C 1 SCXI 1540 User Manual l 2 self test verification troubleshooting 1 6 virtual channels 5 24 multiple channel synchronization figure 2 3 multiplexed mode operation connecting to SCXI 1540 for DAQ device in PXI SCXI combination 1 4 in SCXI chassis 1 4 multiplexed scanning calculating maximum permitted scan rate D 3 channel scanning 5 24 LabVIEW SCXI channel string 5 24 virtual channel string 5 26 low level DAQ functions 5 27 performing scans C and low level DAQ functions 5 27 converting resolver data to angular position 4 8
28. 3 accuracy absolute A 3 table A 4 C C language and low level DAQ functions 5 27 calibration procedures 5 28 using LabVIEW or C based ADE 5 29 CE compliance A 6 channel scanning See multiplexed scanning channel synchronization 2 3 common questions D 1 configuration common questions D 1 excitation frequency 3 2 level 3 2 external synchronization 3 3 gain setting 3 1 troubleshooting self test verification 1 6 wire mode 3 2 connecting SCXI 1540 and resolvers 2 4 connecting SCXI 1540 to DAQ device See DAQ devices connectors front signal connector pin assignments table 2 6 rear signal connector overview 2 7 conventions used in the manual iv National Instruments Corporation l 1 D DAQ device cabling restrictions with plug in E M Series DAQ device D 3 low level DAQ functions and multiplexed scanning 5 27 required limits input range and gain table A 1 unavailable digital lines D 2 DAQ devices connecting to SCXI 1540 for multiplexed scanning in PXI SCXI combination chassis 1 4 in SCXI chassis 1 4 digital signals SCXI 1540 table D 2 unavailable with DAQ device connected table D 2 documentation conventions used in the manual iv E E Series DAQ device cabling restrictions D 3 electromagnetic compatibility A 6 environmental specifications A 5 excitation frequency setting 3 2 level setting 3 2 external synchronization setting 3 3 F frequency excitation 3
29. 3 kS s the sample rate of the E M Series DAQ device is the limiting factor on the maximum acquisition rate of the system in multiplexed mode operation National Instruments Corporation 4 7 SCXI 1540 User Manual Chapter 4 Theory of Operation scaled data in inches SCXI 1540 User Manual Scaling LVDT and RVDT Data Using the SCXI 1540 When using an LVDT or RVDT the fundamental measurement quantities of interest are usually linear or angular position or some quantity derived from a position measurement Converting the SCXI 1540 voltage output signals to these more fundamental quantities involves scaling The easiest way to obtain scaled data from the SCXI 1540 is to use a NI DAQmx task or a Traditional NI DAQ Legacy virtual channel When using a task or channel in your application the data is already scaled based on the information you entered when creating the task or channel Your application need not perform any additional scaling In other cases the analog input data read by your application has only been scaled to equal the rms voltage present at the analog input terminals of the SCXI 1540 This data is a signed quantity with the sign determined by the phase 0 or 180 even though the units are in volts rms If you choose to acquire the raw data in volts you must scale the data in your application using the following formula SCXI 1540 data in volts rms scaled data MEL ON EIER D MU TE DIE ECT
30. 540 User Manual Measurement Studio Visual Basic 6 NET and C When creating an LVDT RVDT task in Visual Basic 6 NET and C follow the general programming flow in Figure 5 1 You can then use the appropriate function calls to modify the task This example creates a new task and configures an NI DAQmx LVDT RVDT channel on the SCXI 1540 You can use the same functions for Visual Basic 6 and In this example an analog input channel object is used since reading the voltage from an LVDT is an analog input operation The following text is a function prototype example void AIChannelCollection CreateLVDTChanneli System String physicalChannelName System String nameToAssignChannel System Double minVal System Double maxVal AILVDTUnits lvdtUnits System Double sensitivity AISensitivityUnits sensitivityUnits AIExcitationSource voltExcitSource System Double voltExcitVal System Double voltExcitFreq AIACExcitWireMode acExcitWireMode 5 12 ni com Chapter 5 Using the SCXI 1540 To actually create and configure the channel you would enter something resembling the following example code Task myTask new NationalInstruments DAQmx Task myTaskName MyTask DAQmxCreateAIPosLVDTChan SC1Mod1 ai0 System String physicalChannelName lvdt0 System String nameToAssignChannel 0 001 System Double minVal 0 001 System Double maxVal AILVDTUnits Inches AIRVDTUnits lvdtUni
31. BILITY 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 Conventions 5 AN A N bold italic monospace monospace bold The following conventions are used in this manual Angle brackets that contain numbers separated by an ellipsis represent a range of values associated with a bit or signal name for example DIO lt 3 0 gt 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 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 When this symbol is marked on a product refer to the Read Me First Safety and Radio Frequency Interference document for information about precautions to take When symbol is marked on a product it denotes a warning advising you to take precautions to avoid electrical shock When symbol is marked on a product it denotes a component that may be hot Touching this component may result in bodily injury Bold text denotes items that you must select or click in the software such as menu items and dial
32. D A 27 28 31 32 SLOT 0 SEL 29 30 33 34 35 36 31 32 37 38 DIG GND 33 34 3220 35 36 AI HOLD COMP AI HOLD 41 42 43 44 SER CLK 37 38 45 46 39 40 47 48 49 50 M is 43 44 45 46 SYNC 47 48 49 50 SCXI 1540 User Manual 2 8 ni com Configuring and Testing This chapter describes the most frequently used software configurable settings for the SCXI 1540 Common Software Configurable Settings This section describes how to set the gain excitation level excitation frequency wire mode and external synchronization Refer to Chapter 4 Theory of Operation for a complete list of software configurable settings Gain Input Range Gain input range is a software configurable setting that allows you to choose the appropriate amplification to fully utilize the range of the E M Series DAQ device In most applications NI DAQ chooses and sets the gain for you as determined by the input range This feature is described in Chapter 4 Theory of Operation Otherwise you should first determine the full scale limits of the SCXI 1540 input signal using the following formula rms full scale range excitation level x sensor sensitivity x sensor full scale travel You then set the upper channel limit to this number and set the lower channel limit to the negative of this number For example if you are using an LVDT designed to measure 0 3 inches the manufacturer sp
33. GND SYNC4 14 14 RSVD 4 EX44 13 im wm ax 13 RSVD GND P4 11 o o o 12 RSVD CH5 CH 5 10 o o 11 RSVD GND SYNCS ce om 10 RSVD EX5 EX 54 8 o 9 RSVD GND P5 7 eleo o o 8 RSVD CH6 CH6 5o o o 7 RSVD GND SYNC6 4 o o 6 RSVD EX 6 EX 6 aie 28 5 RSVD GND P6 2 4 RSVD CH7 CH 74 1 3 RSVD GND SYNC7 2 RSVD EX7 EX7 1 RSVD GND P7 SCXI 1540 User Manual 2 6 ni com Chapter 2 Connecting Signals Rear Signal Connector The rear signal connector RSC is a 50 pin male ribbon cable connector used for analog signal connectivity and communication between the SCXI 1540 and the connected E M Series DAQ device The RSC is shown in Table 2 2 The RSC allows the E M Series DAQ device to access all eight differential analog output signals from the SCXI 1540 For 68 pin E M Series DAQ devices you must connect an adapter to the RSC The positive terminal of each analog output is named CH X and the negative terminal CH X Grounding signals AO GND and OUT REF provide reference signals needed in the various analog input referencing modes on the E M Series DAQ device In multiplexed mode the CH 0 signal pair is used for sending all eight channels of the SCXI 1540 and analog signals from other modules to the connected E M Series DAQ device If the module is directly connected to the E M Series DAQ device the other analog channels of the E M Series DAQ device are unavailable for g
34. HE 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 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 SUITA
35. I D AGQmX ioa pe IRR 3 4 Traditional NI DAQ Legacy essere nennen nnns 3 5 Configuring Module Property 3 5 Creating an LVDT RVDT Virtual Channel esses 3 6 Verifying the Signal cete cie tre t e e iHe nr e tp RE 3 7 Verifying the Signal in NI DAQmx Using a Task or Global Channel 3 7 Verifying the Signal in Traditional NI DAQ Legacy esse 3 8 Verifying the Signal Using Channel Strings s 3 8 Verifying the Signal Using LVDT RVDT Virtual Channel 3 9 Chapter 4 Theory of Operation LNVDTS RVDTS and Resolvers eerte daz eis eset Eee e pee ee Eve 4 SCXI 1540 Theory of Operation eee eeseeseeeseeseceseeeeesececeseeseeeseseeeesesseeeaeesees 4 4 Modes of ote od e eet di ders 4 6 Theory of Multiplexed Mode Operation sess 4 6 Scaling LVDT and Data Using the SCXI 1540 4 8 Converting Resolver Data to Angular Position 4 8 Theory of Parallel Mode Operation sse 4 0 Chapter 5 Using the SCXI 1540 Developing Your Application in NI DAQmx eene 5 1 Typical Program Flowchart 5 1 General Discussion of Typical Flowchart eeeeeeee 5 4 Creating a Task Using DAQ Assistant or Programmatically 5 4 Adjusting Timing and Triggering
36. I DAQmx properties Table 5 1 provides a list of some of the properties that configure the SCXI 1540 You can use this list to determine what kind of properties you need to set to configure the device for your application For a complete list of NI DAQmx properties refer to your ADE help file 3 Note Table 5 1 is not a complete list of NI DAQmx properties and does not include every property you may need to configure LVDTs RVDTs and resolvers It is a representative sample of important properties to configure LVDTs RVDTs and resolvers For a complete list of NI DAQmx properties and more information on NI DAQmx properties refer to your ADE help file Developing Your Application in Traditional NI DAQ Legacy Note If you are not using an NI ADE using an NI ADE prior to version 7 0 or using an unlicensed copy of an NI ADE additional dialog boxes from the NI License Manager appear allowing you to create a task or global channel in unlicensed mode These messages continue to appear until you install version 7 0 or later of an NI ADE This section describes how to configure and use Traditional NI DAQ Legacy to control the SCXI 1540 in LabVIEW LabWindows CVI Measurement Studio and other text based ADEs These NI ADEs provide greater flexibility and access to more settings than MAX but you can use ADEs in conjunction with MAX to quickly create a customized application Traditional NI DAQ Legacy in LabVIEW SCXI 1540
37. IN 25 52 Output P0 4 SERDATOUT 26 19 Input P0 1 DAQD A 27 17 Output P0 2 SLOTOSEL 29 49 Output AI HOLD COMP SCANCLK 36 46 Output AI HOLD EXT SROBE SERCLK 37 45 Output AI SAMP CLK SYNC 46 38 Output AI SAMP SCXI 1540 User Manual In LabVIEW can I use different input limits for the same SCXI 1540 channel if I repeat the channel in the SCXI channel string array No The SCXI 1540 cannot dynamically change the gain settings during scanning Therefore group channels with similar input ranges together in the channel string array Make sure that repeated channels in different indices of the channel string array have the same input limits in the corresponding input limits array In NI DAQmx can I use a VI to change my SCXI 1540 configuration settings Yes You can use the DAQmx Property Node to change all the SCXI 1540 configuration settings D 2 ni com Appendix D Common Questions Are there any cabling restrictions when using an SCXI 1540 module with a plug in E M Series DAQ device Refer to the SCXI Quick Start Guide to determine which module to use as the cabled module A cabled module is the module connected directly to the E M Series DAQ device This ensures that a timing signal from GPCTRO on the E M Series DAQ device is available for use by all simultaneous sampling SCXI modules in the chassis Can I use the SCXI 1540 with a version of NI DAQ that works under the Macintosh Operating System MacOS
38. National Instruments NI DAQ Traditional NI DAQ User Manual Start Programs National Instruments NI DAQ Traditional NI DAQ Function Reference Help e NILVDT RVDT application notes tutorials NI has additional material about LVDT RVDTs available at ni com support You can download NI documents from ni com manuals To download the latest version of NI DAQ click Download Software at ni com National Instruments Corporation 1 8 SCXI 1540 User Manual Chapter 1 About the SCXI 1540 Installing Application Software NI DAQ and the DAQ Device Refer to the DAQ Getting Started Guide packaged with the NI DAQ software to install your application software NI DAQ driver software and the E M Series DAQ device to which you will connect the SCXI 1540 NI DAQ 7 0 or later is required to configure and program the SCXI 1540 module If you do not have NI DAQ 7 0 or later you can either contact a NI sales representative to request it on a CD or download the latest NI DAQ version from ni com ER Note Refer to the Read Me First Radio Frequency Interference document before removing equipment covers or connecting or disconnecting any signal wires Installing the SCXI 1540 Module into the SCXI Chassis Refer to the SCXI Quick Start Guide to install your SCXI 1540 module Connecting the SCXI 1540 in an SCXI Chassis to an E M Series DAQ Device for Multiplexed Scanning Refer to the SCXI Quick Start Guide to install the cab
39. No Some SCXI modules permit random scanning Does the SCXI 1540 module permit random scanning Yes Random scanning is described in Chapter 2 Connecting Signals What is the power up state of the SCXI 1540 multiplexer analog bus switches and configuration settings The multiplexer analog bus switches and configuration settings are not in a known state immediately after power on All hardware settings are programmed automatically when beginning an acquisition in LabVIEW Which accessories can I use to connect signals to the front of the SCXI 1540 module Refer to Chapter 1 About the SCXI 1540 for more information How do I calculate the maximum permitted scan rate when using one or more SCXI 1540 modules in multiplexed mode For the SCXI 1540 and most other SCXI modules the maximum scan rate is limited to a 333 kS s number of scanned channels if the controlling E M Series DAQ device is not the limiting factor National Instruments Corporation D 3 SCXI 1540 User Manual Appendix D Common Questions SCXI 1540 User Manual How do I control the gain frequency excitation level wire mode and synchronization in LabVIEW You can create and save a DAQmx task in Max or programmatically in LabVIEW using DAQmx API VIs The gain of each SCXI 1540 channel is automatically set based on the channel limits used in setting up the task Frequency excitation level wire mode and synchronization mode are also properties of
40. SCXI SCXI 1540 User Manual January 2007 7 NATIONAL 3725818 01 ANiNsrRUMENTS 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 1800 300 800 Austria 43 662 457990 0 Belgium 32 0 2 757 0020 Brazil 55 11 3262 3599 Canada 800 433 3488 China 86 21 6555 7838 Czech Republic 420 224 235 774 Denmark 45 45 76 26 00 Finland 385 0 9 725 72511 France 33 0 1 48 14 24 24 Germany 49 89 7413130 India 91 80 41190000 Israel 972 3 6393737 Italy 39 02 413091 Japan 81 3 5472 2970 Korea 82 02 3451 3400 Lebanon 961 0 1 33 28 28 Malaysia 1800 887710 Mexico 01 800 010 0793 Netherlands 31 0 348 433 466 New Zealand 0800 553 322 Norway 47 0 66 90 76 60 Poland 48 22 3390150 Portugal 351 210 311 210 Russia 7 495 783 6851 Singapore 1800 226 5886 Slovenia 386 3 425 42 00 South Africa 27 0 11 805 8197 Spain 34 91 640 0085 Sweden 46 0 8 587 895 00 Switzerland 41 56 2005151 Taiwan 886 02 2377 2222 Thailand 662 278 6777 Turkey 90 212 279 3031 United Kingdom 44 0 1635 523545 For further support information refer to the Signal Conditioning Technical Support document To comment on National Instruments documentation refer to the National Instruments Web site at ni com info and enter the info code feedback 2000 2007 National Instruments Corporation All rights
41. SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 7 Change the property to read or write to either get the property or write a new value Right click the property go to Change To and select Write Read or Default Value 8 After you have added the property to the property node right click the terminal to change the attributes of the property add a control constant or indicator 5 gt DAQmx Channel 5 AL Excit val AL ACExcit Freg Figure 5 3 LabVIEW Channel Property Node with AC Excitation at 1 Volt RMS and AC Excit Frequency at 2500 Hz 9 To add another property to the property node right click an existing property and left click Add Element To change the new property left click it and select the property you wish to define Note Refer to the LabVIEW Help for information about property nodes and specific NI DAQmx properties Specifying Channel Strings in NI DAQmx SCXI 1540 User Manual Use the channel input of DAQmx Create Channel to specify the SCXI 1540 channels The input control constant has a pull down menu showing all available external channels The strings take one of the following forms e single device identifier channel number for example SC1Mod1 ch0 e multiple noncontinuous channels for example SC1Mod1 ch0 SC1Mod1 ch4 e multiple continuous channels for example SC1Mod1 ch0 4 channels 0 through 4 When you have a task containing SCXI 1540 channels
42. Scale Temperature Drift Exc Offset Freq of Full 100 Pt Gain Drift Offset Drift kHz Typical Max Scale Single Pt Avg 2 5 0 2 0 5 0 05 0 03 0 01 0 03 0 003 3 3 0 2 0 5 0 05 0 03 0 01 0 03 0 003 5 0 2 0 5 0 05 0 03 0 01 0 03 0 003 10 0 5 1 0 0 05 0 03 0 01 0 03 0 003 Absolute accuracy is voltage reading of reading full scale voltage x max offset system noise x full scale voltage To include the effects of temperature drift away from the temperature at which the module was calibrated add the term voltage reading x gain drift x AT full scale voltage x offset drift x AT where AT is temperature change Scan rate for 100 point averages is 200 scans per second Power Requirements deti etes 18 5 to 25 VDC 170 mA min Mucio Pb P ERR 18 5 to 25 VDC 170 mA min 4 75 to 5 25 VDC 50 mA min SCXI 1540 User Manual 4 ni com Appendix A Specifications Physical 3 0 cm 1 2 in o 1 bso 17 2 cm 6 8 in j coca X 18 8 cm 7 4 in Figure A 1 SCXI 1540 Dimensions Weight tetra 727 g 25 6 oz Maximum Working Voltage Maximum working voltage refers to the signal voltage plus the common mode voltage Channel to earth
43. The SCXI 1540 default conditions are e Gain set at 0 8 e 3 Vims excitation level e 10kHz excitation frequency e External synchronization off 4 wire mode SCXI Load Config Loads the SCXI chassis configuration information you established in MAX Sets the software states of the chassis and the modules present to their default states This function makes no changes to the hardware state of the SCXI chassis or modules It is possible to programmatically change the configuration you established in MAX using the SCXI Set Config function SCXI SCAN Setup Initializes multiplexing circuitry for a scanned data acquisition operation Initialization includes storing a table of the channel sequence and gain setting for each channel to be digitized MIO and AI devices only You cannot repeat channels or use nonsequential channels when using the SCXI SCAN Setup function SCXI MuxCtr Setup Programs the E Series DAQ device with the correct number of channels multiplexed per scan This number must match the total number of channels programmed in 5 SCAN Setup hy Note NI strongly recommends monitoring the built in error status of each NI DAQ function The NI DAQ C API provides the NIDAQErrorHandler function which ensures that a specified NI DAQ function executed properly and assists in handling error messages and reporting National Instruments Corporation 5 21 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540
44. XI 1540 of the following Series DAQ device SCXI 1600 module Computer if using an SCXI chassis Cabling cable adapter and sensors as required for your application C Software NI DAQ 7 0 or later of the following software packages LabVIEW Measurement Studio LabWindows CVI C Documentation A Read Me First Safety and Radio Frequency Interference DAQ Getting Started Guide SCXI Quick Start Guide SCXI 1540 User Manual Documentation for your hardware Documentation for your software National Instruments Documentation The SCXI 1540 User Manual is one piece of the documentation set for data acquisition DAQ systems You could have any of several types of manuals depending on the hardware and software in the system Use the manuals you have as follows e SCXI chassis or PXI SCXI combination chassis manual Read this manual for maintenance information on the chassis and for installation instructions The DAQ Getting Started Guide This document has information on installing NI DAQ and the E M Series DAQ device Install these before you install the SCXI module SCXI 1540 User Manual 1 2 ni com Chapter 1 About the SCXI 1540 e The SCXI Quick Start Guide This document contains a quick overview for setting up an SCXI chassis installing SCXI modules and terminal blocks and attaching sensors It also describes setting up the SCXI syste
45. You also can use the LabVIEW Help for more detailed information about how to use graphical controls and indicators in your application Traditional NI DAQ Legacy in Text Based ADEs NI text based ADEs such as LabWindows CVI Measurement Studio for Microsoft Visual Basic and Measurement Studio for Microsoft Visual C offer help in the development of test and measurement applications These ADEs provide easy data acquisition data analysis graphical display and data logging tools Refer to the ADE user manual for more information about how to use these features The high level data acquisition tools provided in LabWindows CVI and Measurement Studio allow you to easily use virtual channels configured in National Instruments Corporation 5 19 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 MAX providing easy configuration and programming of the data acquisition systems However some of the more advanced features of the SCXI 1540 are not accessible through this easy to use API For more advanced features or for more explicit control of the programmatic attributes use the low level DAQ functions provided in the Traditional NI DAQ Legacy C API Refer to the ADE user documentation for more information about how to use the high level data acquisition tools that are provided in your NI ADE For more advanced SCXI 1540 applications or if you are using an ADE other than an NI ADE you can use the Traditional NI DAQ Legacy C API to
46. ab Click the Test button to open the test panel Click the Start button if necessary After you have completed verifying the channels close the test panel window You have now verified the SCXI 1540 configuration and signal connection 3 7 SCXI 1540 User Manual Chapter 3 Configuring and Testing 5 Note For more information on how to further configure SCXI 1540 or how to use LabVIEW to configure the module and take measurements refer to Chapter 4 Theory of Operation Verifying the Signal in Traditional NI DAQ Legacy This section discusses how to verify the signal in Traditional NI DAQ Legacy using channel strings and virtual channels Verifying the Signal Using Channel Strings The format of the channel string is as follows obx scy mdz channel where obx is the onboard E Series DAQ device channel with x representing a particular channel where the multiplexed channels are sent This value is 0 for E Series DAQ device channel 0 in a single chassis system In a multichassis or remote chassis system the E Series DAQ device channel x corresponds to chassis number 1 where E Series DAQ device channel x is used for scanning the nth chassis in the system scy is the SCXI chassis ID where y is the number you chose when configuring the chassis mdz is the slot position where the module is located with z being the particular slot number The slots in a chassis are numbered from left to right star
47. aligned in the slot After checking the preceding items return to the Troubleshooting the Self Test Verification section and retest the SCXI chassis If these measures do not successfully configure the SCXI system contact NI Refer to the Signal Conditioning Technical Support document for contact information SCXI 1540 User Manual 1 8 ni com Connecting Signals This chapter describes how to interface the SCXI 1540 with an LVDT RVDT or resolver Connecting to LVDTs and RVDTs Figures 2 1 and 2 2 show the connections made to a 4 wire and 5 wire LVDT or RVDT using the SCXI 1540 with the SCXI 1315 terminal block Figure 2 1 also shows how you can connect a device with six wires using only four wires Red o CH E Blue o CH Brown Yellow Gian o SYNC Y TE o GND o EX o EX Figure 2 1 4 Wire Connection to an LVDT or RVDT National Instruments Corporation 2 1 SCXI 1540 User Manual Chapter 2 Connecting Signals 4 A o CH Brown Blue o CH Yellow Green N o SYNC Y e Black o GND o Figure 2 2 5 Wire Connection to an LVDT or RVDT In general the 5 wire connection is insensitive to phase shift in the transducer and wiring but subject to interference from common mode voltages in the cable such as AC hum picked up from power lines transformers and motors It is advisable therefore to use the 4 wir
48. and frequency through your application In National Instruments Corporation 3 3 SCXI 1540 User Manual Chapter 3 Configuring and Testing NI DAQmx you can choose 1 or 3 The default voltage excitation in NI DAQmx is 3 V You can also set the frequency between 2 5 and 10 KHz Refer to Appendix A Specifications for the valid frequencies Input signal range configure the input signal range using either NI DAQmx Task or NI DAQmx Global Channel When you set the minimum and maximum range of NI DAQmx Task or NI DAQmx Global Channel the driver selects the best gain for the measurement You also can set it through your application The default gain setting in NI DAQmx is 1 0 This setting corresponds to an input range of 5 V cs Wire mode you can set the wire mode to either 4 or 5 wire mode as needed by your application e Modes of operation configure as multiplexed or parallel mode when you configure the SCXI chassis Refer to the SCXI Quick Start Guide for more information about chassis installation parallel mode is only available for the SCXI 1540 when you use NI DAQmx yi Note Refer to Chapter 4 Theory of Operation for information on configuring the settings for your application using NI DAQmx SCXI 1540 User Manual Creating an LVDT RVDT Global Channel or Task in NI DAQmx To create anew NI DAQmx LVDT RVDT global task or channel complete the following steps 1 Double click Measurement amp Automa
49. ange for the particular LVDT in use The signal then passes to a block where it is multiplied by the excitation signal The output of the multiplier is the product of two sine waves at the same frequency Two signals result a DC signal proportional to input magnitude or equivalently LVDT core position and a double frequency signal The lowpass filter removes the double frequency signal Only the DC signal passes through which is the final output signal for the particular channel The analog multiplexer routes a particular channel output to either the SCXIbus connector or the rear signal connector The SCXI 1540 features random scanning meaning you can scan channels in any order The input selector switch allows calibration software to disconnect the differential amplifier from the front signal connector and reconnect it to the ground or excitation signal at either phase It is therefore possible to calibrate gain and offset of the module with the module deployed in a test setup You need not remove the field wiring Calibration constants are stored in an onboard EEPROM and automatically used in the driver when scaling the signal Modes of Operation SCXI 1540 User Manual The SCXI 1540 provides two modes of operation for passing the conditioned signals to the digitizing E M Series DAQ device multiplexed mode and parallel mode Theory of Multiplexed Mode Operation In multiplexed mode all input channels of an SCXI module are multiplex
50. applying a custom scale or adjusting measurements mathematically NI provides powerful analysis toolsets for each NI ADE to help you perform advanced analysis on the data without requiring you to have a programming background After you acquire the data and perform any required analysis it is useful to display the data in a graphical form or log it to a file NI ADEs provide easy to use tools for graphical display such as charts graphs slide controls and gauge indicators NI ADEs have tools that allow you to easily save the data to files such as spread sheets for easy viewing ASCII files for universality or binary files for smaller file sizes Completing the Application After you have completed the measurement analysis and presentation of the data it is important to stop and clear the task This releases any memory used by the task and frees up the DAQ hardware for use in another task 3 Note In LabVIEW tasks are automatically cleared when the program is stopped Developing an Application Using LabVIEW This section describes in more detail the steps shown in the typical program flowchart in Figure 5 1 such as how to create a task in LabVIEW and configure the channels of the SCXI 1540 If you need more information or for further instructions select Help VI Function amp How To Help from the LabVIEW menu bar Note Except where otherwise stated the VIs in Table 5 2 are located on the Functions All Functions NI Measureme
51. ble between the SCXI chassis and E Series DAQ device is properly connected Inspect the cable connectors for bent pins National Instruments Corporation 1 7 SCXI 1540 User Manual Chapter 1 About the SCXI 1540 Make sure you are using the correct NI cable assembly Test the E Series DAQ device to verify it is working properly Refer to the E Series DAQ device help file for more information If you get the message Failed to find followed by module codes and the message Instead found module with ID refer to the Traditional NI DAQ Legacy section of Chapter 3 Configuring and Testing and make sure the correct module is in the specified slot Delete the incorrect module as described in Appendix C Removing the SCXI 1540 and add the correct module as described in the Traditional NI DAQ Legacy section of Chapter 3 Configuring and Testing If you get the message Failed to find followed by a module code and the message Slot x is empty make sure the configured module is installed in the specified slot If not install the module by following the instructions in the SCXI Quick Start Guide If the module is installed in the correct slot power off the chassis remove the module as specified in Appendix C Removing the SCXI 1540 and verify that no connector pins are bent on the rear signal connector Reinstall the module as described in the SCXI Quick Start Guide ensuring the module is fully inserted and properly
52. detect the SCXI modules you must manually add each of the modules Refer to the SCXI Quick Start Guide to manually add modules iyi Note NI recommends auto detecting modules for the first time configuration of the chassis Verifying and Self Testing the Installation The verification procedure for the SCXI chassis is the same for both NI DAQmx and Traditional NI DAQ Legacy To test the successful installation for the SCXI chassis refer to the SCXI Quick Start Guide Verify that the chassis is powered on and correctly connected to an E M Series DAQ device National Instruments Corporation 1 5 SCXI 1540 User Manual Chapter 1 About the SCXI 1540 After verifying and self testing the installation the SCXI system should operate properly with your ADE software If the test did not complete successfully refer to Chapter 3 Configuring and Testing for troubleshooting steps Troubleshooting the Self Test Verification If the self test verification did not verify the chassis configuration complete the steps in this section to troubleshoot the SCXI configuration Troubleshooting in NI DAQmx e Ifyou get a Verify SCXI Chassis message box showing the SCXI chassis model number Chassis ID x and one or more messages stating Slot Number x Configuration has module SCXI XXXX or 1540 hardware in chassis is Empty take the following troubleshooting actions Make sure the SCXI chassis is powered on Make sure all SCXI modu
53. e Mode Properties Y Start Acquisition Take Measurements Continue Sampling No Scale Analyze and Display y Clear Acquisition Y Error Handling Figure 5 4 Typical SCXI 1540 Program Flow with Traditional NI DAQ Legacy 5 16 ni com Chapter 5 Using the SCXI 1540 Configure the SCXI 1540 Settings Using Traditional NI DAQ Legacy in LabVIEW To configure and control the SCXI 1540 from LabVIEW use the AI Parameter VI You can find AI Parameter VI in the function subpalette Data Acquisition Analog Input Advanced Analog Input A parameter changed by the AI Parameter VI takes effect in hardware when AI Start VI is called not when AI Parameter VI is called The AI parameter VI merely changes the configuration in the driver memory When called the AI Start VI reads the configuration settings in the driver memory and then sends the actual control information to the SCXI 1540 module A setting established through AI Parameter VI is only valid for the LabVIEW session and does not change the setting in MAX You can use the AI Parameter VI to configure the SCXI 1540 settings shown in Table 5 3 Table 5 3 Settings for Configuring the SCXI 1540 Through the AI Parameter Software Configurable Setting Allowable Settings Float In Boolean I lue I AI Parameter VI Float In Boolean In or Value In Parameter Name Data Type Values Excitation Le
54. e connection except in cases where a large phase shift in the return signal is suspected Causes for a large phase shift might be the use of an operating frequency other than that specified by the sensor manufacturer or a cable length greater than 100 m iyi Note The default configuration setting for the SCXI 1540 is 4 wire Refer to Chapter 5 Using the SCXI 1540 for more information about programming the SCXI 1540 in 5 wire mode SCXI 1540 User Manual 2 2 ni com Chapter 2 Connecting Signals Synchronizing Channels Figure 2 3 shows how to synchronize multiple SCXI 1540 channels to the same frequency You should do this for all channels that have wires sharing a single multi conductor cable Synchronization prevents beat frequencies from appearing in the data Beat frequencies are the result of channel oscillators running at slightly different frequencies and coupling into adjacent channels through cable crosstalk o 3 mee 2 Master Channel 6 diis Do not Configure o GND for External Synchronization o o EXO o CH1 3 mE Lo SYNCI Slave Channel Configure for o GND External Synchronization o o EX1 o CH2 sos fi SYNC2 Slave Channel Configure for o GND External Synchronization o EX2 o EX2 Figure 2 3 Multiple Channel Synchronization National Instruments Corporatio
55. e all that is needed to convert measured voltages to degrees is an arctangent function there are no scaling considerations SCXI 1540 Theory of Operation SCXI 1540 User Manual Figure 4 3 is a block diagram of the SCXI 1540 Each channel has an oscillator that generates a sine wave signal at a user selected frequency between 2 5 and 10 kHz The oscillator signal passes through an amplifier with a gain of 1 or 1 3 depending upon the configuration setting of 3 V or 1 Vins respectively If external synchronization is not enabled the excitation signal is routed to the output buffer and then to the front signal connector pins EX and EX The output buffers are power amplifiers with a very low output impedance used for differentially driving an LVDT EX is 180 out of phase with EX so that a balanced signal is available to the LVDT secondary If external synchronization is enabled the buffered output signal to EX and EX is obtained from the SYNC terminal on the front signal connector This terminal connects to the EX terminal of a different channel that serves as master Thus the frequency and phase of all slave channels are forced to be the same as the master The level settings pass from the master to the slaves Changing the level settings of the slave channels has no effect 4 4 ni com Theory of Operation Chapter 4 SCXlIbus Connector Rear Signal Connector
56. e for more detailed information on programming your SCXI modules for scanning in multiplexed mode LabVIEW and the SCXI Channel String For LabVIEW and Visual Basic 6 the channel string determines the sequence in which SCXI channels are scanned Refer to Appendix B Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later for more information about using SCXI channels strings in 5 24 ni com Chapter 5 Using the SCXI 1540 Traditional NI DAQ Legacy In LabVIEW an array of these channel strings configures multiple modules in the scan list When the application program runs the channel string is used for programming the channel information into the SCXI system The format of the channel string is as follows obx scy mdz channels where obx is the onboard E Series DAQ device channel with x representing a particular channel where the multiplexed channels are sent This value is 0 for DAQ channel 0 in a single chassis system In a multichassis or remote chassis system however the E Series DAQ device channel x corresponds to chassis number 1 where E Series DAQ device channel x is used for scanning the nth chassis in the system scy is the SCXI chassis ID where y is the number you chose when configuring your chassis mdz is the slot position where the module is located with z being the particular slot number The slots in a chassis are numbered from left to right starting with 1 iyi Note The obx
57. e you load the task the task uses the settings originally configured in the DAQ Assistant Adjusting Timing and Triggering There are several timing properties that you can configure through the DAQ Assistant or programmatically using function calls or property nodes If you create a task in the DAQ Assistant you can still modify the timing properties of the task programmatically in your application 5 4 ni com Chapter 5 Using the SCXI 1540 When programmatically adjusting timing settings you can set the task to acquire continuously acquire a buffer of samples or acquire one point at a time For continuous acquisition you must use a while loop around the acquisition components even if you configured the task for continuous acquisition using MAX or the DAQ Assistant For continuous and buffered acquisitions you can set the acquisition rate and the number of samples to read in the DAQ Assistant or programmatically in your application By default the clock settings are automatically set by an internal clock based on the requested sample rate You also can select advanced features such as clock settings that specify an external clock source internal routing of the clock source or select the active edge of the clock signal Configuring Channel Properties All ADEs used to configure the SCXI 1540 access an underlying set of NI DAQmx properties Table 5 1 shows some of these properties You can use Table 5 1 to determine what kind of prop
58. ecified sensitivity is 1 2 mV V mil and the excitation voltage is set at 3 Vms you obtain a full scale input voltage of 1 08 8 X 00 0012 per Vins per mil x 300 mil You then set the upper and lower channel input limits to 1 08 V and 1 08 V respectively A mil is equal to 0 001 in Refer to Chapter 5 Using the SCXI 1540 for more information about setting the gain programmatically National Instruments Corporation 3 1 SCXI 1540 User Manual Chapter 3 Configuring and Testing Excitation Level The formula for the gain setting is gain setting 5 V V full scale range The maximum output swing of the SCXI 1540 is 5 VDC therefore the gain calculation is 5 V divided by the full scale limit Gain in the case of the SCXI 1540 is defined as the module DC output voltage divided by the module AC input voltage where the input voltage is given in units of volts rms You should choose the setting that is closest to the calculated value but less than the calculated value so that the SCXI 1540 output does not attempt to go beyond 5 V at full scale You may set the excitation at 1 or 3 Vms The higher setting is recommended in all applications except where the driven AC impedance is less than 95 Q or where the sensor manufacturer recommends a lower excitation level When set for external excitation match this value to the level of the excitation source Excitation Frequency Excitation Source
59. ection You must not configure the channel that originates the synchronization signal from its EX pin for external synchronization since that channel serves as master and is not slaved to any other channel Perform Scaling Analysis and Display After acquiring raw voltage data from the acquisition functions most applications require adjustment by device calibration constants for accuracy scaling measured voltage analysis and graphical display The SCXI 1540 has stored software calibration constants loaded on the module EEPROM that are used to achieve the absolute accuracy specifications SCXI Scale scales an array of binary data acquired from an SCXI channel to voltage using the stored software calibration constants when it scales the data You must call SCAN Demux before SCXI Scale if you have multiple channels in the scan For more information regarding SCXI Scale refer to the Traditional NI DAQ Legacy Function Reference Help installed by default in Start Programs National Instruments NI DAQ NI ADEs provide many powerful analysis National Instruments Corporation 5 23 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 functions to perform digital filtering harmonic analysis averaging and complex mathematics on measurements After performing scaling and analysis on the acquired data you can display the measurements in several ways You can use any built in GUI tools in your ADE NI ADEs provide many graphical contr
60. ed into a single analog input channel of the E M Series DAQ device Multiplexed mode operation is ideal for high channel count systems Multiplexed mode is typically used for performing scanning operations with the SCXI 1540 The power of SCXI multiplexed mode scanning is its ability to route many input channels to a single channel of the E M Series DAQ device The multiplexing operation of the analog input signals is performed entirely by multiplexers in the SCXI modules not inside the E M Series DAQ device or SCXI chassis In multiplexed mode the SCXI 1540 scanned channels are kept by the NI DAQ driver in a scan list Immediately 4 6 ni com Chapter 4 Theory of Operation prior to a multiplexed scanning operation the SCXI chassis is programmed with a module scan list that controls which module sends its output to the SCXIbus during a scan through the cabled SCXI module The list can contain channels in any physical order and the multiplexer can sequence the channel selection from the scan list in any order The ordering of scanned channels need not be sequential Channels can occur multiple times in a single scan list The scan list can contain an arbitrary number of channels for each module entry in the scan list limited to a total of 512 channels per E M Series DAQ device This is referred to as flexible scanning random scanning Not all SCXI modules provide flexible scanning The module includes first in first out FIFO memory for
61. eneral purpose analog input because they are still connected to the amplifier outputs of the SCXI 1540 in multiplexed mode The communication signals between the E M Series DAQ device and the SCXI system are SER DAT IN SER DAT OUT DAQ D A SLOT 0 SEL SER CLK and AI HOLD COMPI HOLD The digital ground DIG GND on pins 24 and 33 provides a separate ground reference for the communication signals SER DAT IN SER DAT OUT DAQ D A SLOT 0 SEL and SER CLK are the communication lines for programming the SCXI 1540 The AI HOLD COMP AI HOLD and SYNC signals are the signals necessary for multiplexed mode scanning If Series DAQ device is connected to the SCXI 1540 these digital lines are unavailable for general purpose digital I O National Instruments Corporation 2 7 SCXI 1540 User Manual Chapter 2 Connecting Signals Table 2 2 Rear Signal Pin Assignments Rear Connector Diagram Signal Name Pin Number Pin Number Signal Name AIGND 1 2 AI GND 3 4 CH0 CH1 5 6 CH1 T2 CH2 7 8 CH2 3 4 CH3 9 10 CH3 5 6 CH4 11 12 CH4 718 10 CH5 13 14 CH5 ae CH6 15 16 CH6 13 14 15 16 CH7 17 18 CH7 17 18 OUT REF 19 20 19 20 21 22 23 24 23 24 DIG GND gt 26 SER DAT IN 25 26 SER DAT OUT 27 28 29 30 DAQ
62. erties you need to set to configure the module for your application For a complete list of NI DAQmx properties refer to your ADE help file 3 Note You cannot adjust some properties while a task is running For these properties you must stop the task make the adjustment and re start the application Table 5 1 assumes all properties are configured before the task is started Table 5 1 NI DAQmx Properties Property Short Name Description Analog Input General Properties AI Rng High Specifies the upper Advanced Range High limit of the input range on the digitizer device Analog Input General Properties AI Rng Low Specifies the lower Advanced Range Low limit of the input range on the digitizer device Analog Input General Properties ALExcit Val Specifies the amount Signal Conditioning Excitation of excitation in RMS Value volts Analog Input General Properties ALACExcit Freq Specifies the Signal Conditioning Excitation frequency of AC AC Excitation Frequency excitation National Instruments Corporation 5 5 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 Table 5 1 NI DAQmx Properties Continued Property Short Name Description Analog Input General Properties AI ACExcit SyncEnable Specifies whether to Signal Conditioning Excitation synchronize the AC AC Excitation Synchronization excitation source of the Enable channel to that of anothe
63. et the DAQmx Timing vi sample mode to Continuous Samples To do this right click the terminal of the DAQmx Timing vi labeled sample mode and click Create Constant Click the box that appears and select Continuous Samples Stop Measurement DAQmx Stop Task vi This VI is optional clearing the task automatically stops the task Clear Task DAOmx Clear Task vi Using a DAQmx Channel Property Node in LabVIEW You can use property nodes in LabVIEW to manually configure the channels To create a LabVIEW property node complete the following steps 1 Launch LabVIEW 2 Create the property node in a new VI or in an existing VI 3 Open the block diagram view 4 From the Functions toolbox select Functions NI Measurements DAQmx Data Acquisition and select DAQmx Channel Property Node 5 The ActiveChans property is displayed by default This allows you to specify exactly what channel s you want to configure If you want to configure several channels with different properties separate the lists of properties with another Active Channels box and assign the appropriate channel to each list of properties iyi Note If you do not use Active Channels the properties are set on all of the channels in the task 6 Right click ActiveChans and select Add Element Left click the new National Instruments Corporation ActiveChans box Navigate through the menus and select the property you wish to define 5 9
64. ew 1 1 power up state D 3 removing figure C 2 removing from SCXI chassis C 1 scaling LVDT and RVDT data 4 8 self test troubleshooting D 1 specifications A 1 theory of operation 4 4 using 2 1 virtual channel string 5 26 self test verification troubleshooting 1 6 D 1 signal connections front signal connector 2 5 pin assignments table 2 6 LVDTs and RVDTs 2 1 rear signal connector 2 5 resolvers 2 4 synchronizing channels 2 3 software using for multiplexed scanning 5 24 specifications absolute accuracy A 3 CE compliance A 6 electromagnetic compatibility A 6 environmental A 5 general specifications A 1 input range gain and required DAQ device limits table A 1 maximum working voltage A 5 physical A 5 SCXI 1540 User Manual Index power requirements 4 safety A 6 synchronization external 3 3 4 4 multiple channel synchronization 2 3 T theory of operation 4 4 troubleshooting self test verification 1 6 D 1 SCXI 1540 User Manual V verifying and self testing the configuration troubleshooting 1 6 virtual channel string 5 24 LabVIEW 5 26 voltage maximum working A 5 W wire mode setting 3 2 ni com
65. g system I have gone over the Verifying and Self Testing the Installation in Chapter 1 About the SCXI 1540 yet I still cannot correctly test and verify that my SCXI 1540 is working What should I do now Unfortunately there always exists the chance that one or more components in your system are not operating correctly You may have to call or e mail atechnical support representative The technical support representative will often suggest additional troubleshooting measures If requesting technical support by phone have your system nearby so you can try these measures immediately Can I use the unused analog input channels of the E M Series DAQ device if I am directly cabled to the SCXI 1540 No E M Series DAQ device channels 1 through 7 connect to the conditioned analog outputs of SCXI 1540 channels 1 through 7 National Instruments Corporation D 1 SCXI 1540 User Manual Appendix D Common Questions Which digital lines are unavailable on the E M Series DAQ device if I am cabled to an SCXI 1540 module Table D 1 shows the digital lines that are used by the SCXI 1540 for communication and scanning These lines are unavailable for general purpose digital I O if the SCXI 1540 is connected to the E M Series DAQ device Table D 1 Digital Signals on the SCXI 1540 Direction with respect to the E M DAQ SCXI 50 Pin 68 Pin Series DAQ Signal Name Signal Name Connector Connector device P0 0 SERDAT
66. hardware from the drop down menu c Which analog input mode will be used from the drop down menu SCXI 1540 User Manual 3 6 ni com 9 Chapter 3 Configuring and Testing d Whatis the Excitation Voltage s source and value from the drop down menu e Voltage in volts rms Click Finish Verifying the Signal This section describes how to take measurements using test panels in order to verify signal and configuring and installing a system in NI DAQmx and Traditional NI DAQ Legacy Verifying the Signal in NI DAQmx Using a Task or Global Channel You can verify the signals on the SCXI 1540 using NI DAQmx by completing the following steps National Instruments Corporation 1 Expand the list of tasks and virtual channels by clicking the next to Data Neighborhood Click the next to NI DAQmx Tasks to expand the list of tasks Click the task Add or remove channels if applicable in the Channel List Click the Add Channels button shown at left and select the type of channel you want to add a Inthe window that appears expand the list of channels by clicking the next to the module of interest b Selectthe channel s you want to verify You can select a block of channels by holding down the Shift key or multiple channels by holding down the lt Ctrl gt key Click OK Enter the appropriate information on the Settings tab Click the Device tab and enter the appropriate information on the Device t
67. ily sequential obx scy mdz n0 n3 where n0 and n3 represent an ascending sequential list of input channels inclusive scy mdz n0 n2 n3 n4 n1 n5 n2 where n0 n2 and n5 represent single channels not necessarily sequential and n3 and n4 represent the endpoints of an ascending sequential list of channels inclusive In this case channels n1 and n2 are explicitly repeated in the channel list ik Notes Using parenthesis surrounding multiple channels in a channel string is important for correct scanning operation of the SCXI channels In a single chassis system the obx specifier is optional and causes the gains on the module and E Series DAQ device to be automatically set to fit the input limits parameter When this specifier is omitted the default gain on the E Series DAQ device usually the lowest gain is used but the SCXI 1540 gain is adjusted to fit the input limits NI recommends using the obx specifier Repeating channels or having channels out of sequence in a scan list is not supported on all SCXI modules Refer to the manual of each module for information on this feature which is referred to as flexible scanning or random scanning For more information about using SCXI channel string refer to the LabVIEW Measurements Manual and SCXI 1540 shipping examples Special SCXI 1540 Channel Strings You can use the calibration ground channel string with the SCXI 1540 to acquire signals from alternat
68. ionalInstruments CVI 8 x Samples More examples are installed by default in C Program Files WNational Instruments NNI DAQNExamples Traditional NI DAQ Legacy Measurement Studio Examples Many example programs ship with NI DAQ For more example information on how to create tasks and channels refer to the example programs By default the example programs are installed in C Program FilesWNationalInstruments Measurement Studio 7 0 examples are installed by default in c Program Files National Instruments NNI DAQN Examples Calibration The SCXI 1540 is shipped with a calibration certificate and is calibrated at the factory to the specifications described in Appendix A Specifications Calibration constants are stored inside the calibration EEPROM and provide software correction values your application development software uses to correct your measurements for both offset and gain errors in the module You may want to periodically calibrate the module for offset and gain drift using the procedures described in the Calibration Procedures section Calibration Procedures You can calibrate the offset and gain on the SCXI 1540 using National Instruments software The SCXI 1540 provides input switching that automatically connects the input terminals to the excitation terminals when you perform a calibration There is generally no need to change the input wiring since this connection is made internally and the front panel input
69. ive locations rather than the signal inputs on the channels This section describes the use of these channels Calibration Ground Channel String The SCXI 1540 has a special calibration feature that enables LabVIEW to ground the module amplifier inputs so that you can read the amplifier offset For the other SCXI analog input modules you must physically wire the terminals to ground The measured amplifier offset is for the entire signal path including the SCXI module and the E Series DAQ device SCXI 1540 User Manual B 2 ni com Appendix B Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later To read the grounded amplifier on the SCXI 1540 use the standard SCXI string syntax in the channels array with calgndz substituted for the channel number where z is the appropriate SCXI channel needing grounding For example use the SCXI channel string sci md1 calgndO to read the grounded channel 0 signal of the module in slot 1 of SCXI chassis 1 The resulting measurement should be very close to 0 V The AI Start VI grounds the amplifier before starting the acquisition The AI Clear VI removes the grounds from the amplifier after the acquisition completes You can specify a range of channels also The string calgnd0 7 grounds the amplifier inputs for channels 0 through 7 and reads the offset for each amplifier Use the SCXI Calibrate VI available on the Functions Data Acquisition Calibration and Configuratio
70. l in unlicensed mode These messages continue to appear until you install version 7 0 or later of an NI ADE This section describes where you can access each software configurable setting for modification in MAX The location of the settings varies depending on the version of NI DAQ you use Refer to either the NI DAQmx section or the Traditional NI DAQ Legacy section You also can refer to DAQ Getting Started Guide and the SCXI Quick Start Guide for more information on installing and configuring the hardware You also can use the DAQ Assistant to graphically configure common measurement tasks channels or scales NI DAQmx In NI DAQmx you can configure software settings such as voltage excitation level and frequency gain input signal range wire mode and external synchronization in the following ways e Task or global channel in MAX e Functions in your application Note All software configurable settings are not configurable both ways This section only discusses settings in MAX Refer to Chapter 4 Theory of Operation for information on using functions in your application These sections describe settings that you can change in MAX and where they are located Voltage LVDT or RVDT are the NI DAQmx Task or NI DAQmx Global Channel types you can use with the SCXI 1540 e Voltage excitation level and frequency configure using either NI DAQmx Task or NI DAQmx Global Channel You also can set the voltage excitation level
71. le adapter and connect the SCXI modules to the E M Series DAQ device If you have already installed the appropriate software refer to Chapter 3 Configuring and Testing to configure the SCXI 1540 module s Connecting the SCXI 1540 in a PXI SCXI Combination Chassis to an E M Series DAQ Device for Multiplexed Scanning Refer to the SCXI Quick Start Guide to connect the SCXI modules to the E M Series DAQ device If you have already installed the appropriate software refer to Chapter 3 Configuring and Testing to configure the SCXI 1540 module s SCXI 1540 User Manual 1 4 ni com Chapter 1 About the SCXI 1540 Verifying the SCXI 1540 Installation in Software Refer to the SCXI Quick Start Guide for information on verifying the SCXI installation Installing SCXI Using NI DAQmx in Software Refer to the SCXI Quick Start Guide for information on installing modules using NI DAQmx in software Manually Adding Modules in NI DAQmx If you did not auto detect the SCXI modules you must manually add each of the modules Refer to the SCXI Quick Start Guide to manually add modules 3 Note NI recommends auto detecting modules for the first time configuration of the chassis Installing SCXI Using Traditional NI DAQ Legacy in Software Refer to the SCXI Quick Start Guide for information on installing modules using Traditional NI DAQ Legacy in software Manually Adding Modules in Traditional NI DAQ Legacy If you did not auto
72. les are properly installed in the chassis Refer to the SCXI Quick Start Guide for proper installation instructions Make sure the cable between the SCXI chassis and E M Series DAQ device is properly connected nspect the cable connectors for bent pins Make sure you are using the correct NI cable assembly Test the E M Series DAQ device to verify it is working properly Refer to the E M Series DAQ device help file for more information e Ifyou get a Verify SCXI Chassis message box showing the SCXI chassis model number Chassis ID x and the message Slot Number x Configuration has module SCXI XXXX or 1540 hardware in chassis is SCXI YYYY 1540 or Empty complete the following troubleshooting steps to correct the error 1 Expand the list of NI DAQmx devices by clicking the next to NI DAQmx Devices 2 Right click the SCXI chassis and click Properties to load the chassis configurator 3 Under the Modules tab ensure that the cabled module is listed in the correct slot SCXI 1540 User Manual 1 6 ni com Chapter 1 About the SCXI 1540 4 Ifthe cabled module is not listed in the correct slot complete the following troubleshooting steps If the cabled module is not listed in the correct slot and the slot is empty click the drop down listbox next to the correct slot and select the cabled module Configure the cabled module following the steps listed in the SCXI Quick Start Guide Click OK b Ifanother
73. lly Master Channel Sine Stator Create Voltage Channel 1 Set the Following Properties e Set Excitation Source Internal e Set External Sychronization False e Set Excitation Level 1 or 3 Vrms e Set Wire Mode 4 Wire e Set Excitation Frequency Slave Channel Cosine Stator Start Measurement y Set the Following Properties e Set Excitation Source External e Set External Sychronization True e Set Wire Mode 4 Wire e Set Excitation Level Same as Master Channel Read Measurement No Hardware Timing Triggering Adjust Timing Settings Analyze Data Graphical Display Tools No Stop Measurement Clear Task angle arctan Display Data Continue Sampling Master chanel Slave Channel Yes Figure 5 2 Typical Program Flowchart for Resolver Channels National Instruments Corporation 5 3 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 5 Note Refer to Chapter 2 Connecting Signals Figure 2 4 for physical connections General Discussion of Typical Flowchart SCXI 1540 User Manual The following sections briefly discuss some considerations for a few of the steps in Figure 5 1 These sections are meant to give an overview of some of the options and features available when programming with NI DAQmx Creating a Task Using DAQ Assis
74. m in MAX e The SCXI hardware user manuals Read these manuals next for detailed information about signal connections and module configuration They also explain in greater detail how the module works and contain application hints e Accessory installation guides or manuals Read the terminal block and cable assembly installation guides They explain how to physically connect the relevant pieces of the system Consult these guides when you are making the connections e The E M Series DAQ device documentation This documentation has detailed information about the E M Series DAQ device that plugs into or is connected to the computer Use this documentation for hardware installation and configuration instructions specification information about the E M Series DAQ device and application hints e Software documentation You may have both application software and NI DAQ software documentation National Instruments NI application software includes LabVIEW LabWindows CVI and Measurement Studio After you set up the hardware system use either your application software documentation or the NI DAQ documentation to help you write your application If you have a large complex system it is worthwhile to look through the software documentation before you configure the hardware e One or more of the following help files for software information Start Programs National Instruments NI DAQ NI DAQmx Help Start Programs
75. max Input gain Refer to Table A 1 Input gain 2 Gain dift ua e 300 ppm C max Input damage level power on 32 V mms Excitation Frequency ace eet 2 5 kHz 10 3 3 kHz 10 5 0 kHz 10 10 0 kHz 10 Level Low 1 Vims 5596 High setting 3 Vms 596 Minimum load impedance 32 Q for 1 Vms setting 95 Q for 3 Vms setting Absolute accuracy includes the cumulative error of both excitation and input gain after the application of software correction coefficients The software correction coefficients reside in the onboard EEPROM and are applied automatically to acquired data when using NI DAQmx tasks or Traditional NI DAQ Legacy virtual channels This is the error before correction in software Input gain error excitation level error and output offset error are accounted for in the software correction coefficients stored in the onboard EEPROM These constants are applied automatically when using NI DAQmx tasks or Traditional DAQ Legacy virtual channels The specifications in the Absolute Accuracy section indicate overall accuracy of the SCXI 1540 including the application of the software correction coefficients National Instruments Corporation A 3 SCXI 1540 User Manual Appendix A Specifications Table A 2 Absolute System Accuracy System Noise of Reading Max Peak of Full
76. module appears where the cabled module should be click the drop down listbox next to the correct slot and select the cabled module A message box appears asking you to confirm the module replacement Click OK Configure the cabled module following the steps listed in the SCXI Quick Start Guide Click OK e Ensure that you have the highest priority SCXI module cabled to the E M Series DAQ device Refer to the SCXI Quick Start Guide to find out which SCXI module in the chassis should be cabled to the E M Series DAQ device e After checking the preceding items return to the Troubleshooting the Self Test Verification section and retest the SCXI chassis If these measures do not successfully configure the SCXI system contact NI Refer to the Signal Conditioning Technical Support Information document for contact information Troubleshooting in Traditional NI DAQ Legacy e Ifyou get the message Unable to test chassis at this time you have not designated at least one module as connected to a E Series DAQ device Refer to the Traditional NI DAQ Legacy section of Chapter 3 Configuring and Testing and change the configuration of the cabled module in the system from Connected to None to Connected to Device x e Ifyou get the message Failed to find followed by the module codes and the message Unable to communicate with chassis take the following troubleshooting actions Make sure the SCXI chassis is powered on Make sure the ca
77. n 2 3 SCXI 1540 User Manual Chapter 2 Connecting Signals B Note To synchronize multiple channels you must make the connections shown in Figure 2 3 and configure the slaved channels as externally synchronized Refer to Chapter 5 Using the SCXI 1540 for details about programming the SCXI 1540 for external synchronization You must not configure the channel that originates the synchronization signal from its EX pin channel 0 in the example of Figure 2 3 for external synchronization since that channel serves as master and is not slaved to any other channel Connecting to Resolvers Figure 2 4 shows the connections made between a resolver and the SCXI 1540 using the SCXI 1315 terminal block A single resolver requires the use of two channels You must synchronize both channels using a wire connecting the EX on the master channel to the SYNC on the slave channel Configure the slave channel for external synchronization as described in the Synchronizing Channels section You can also synchronize more than two channels used for resolvers or combinations of resolvers LVDTs and RVDTs by the previously described method Refer to Chapter 5 Using the SCXI 1540 Figure 5 2 for steps involved in programming resolvers o 3 o CHO cosine o SYNCO Slave Channel TAY C stator Configure for o GND External Synchronization o o EX0 1 o CH1 Master Channel o SYNC1 Do not Configure o GND
78. n palette to automatically perform a self calibration and modify the scaling constants on the module to adjust for any amplifier offset Refer to the Calibration Using LabVIEW or a C Based ADE section of Chapter 5 Using the SCXI 1540 for more information about how to use SCXI Calibrate VI with the SCXI 1540 National Instruments Corporation B 3 SCXI 1540 User Manual Removing the SCXI 1540 This appendix explains how to remove the SCXI 1540 from MAX and an SCXI chassis or PXI SCXI combination chassis Removing the SCXI 1540 from MAX To remove a module from MAX complete the following steps after launching MAX 1 Expand Devices and Interfaces 2 Click the next to NI DAQmx and or Traditional NI DAQ Devices to expand the list of installed chassis 3 Click the next to the appropriate chassis to expand the list of installed modules 4 Right click the module or chassis you want to delete and click Delete A confirmation window opens Click Yes to continue deleting the module or chassis or No to cancel this action hy Note Deleting the SCXI chassis deletes all modules in the chassis All configuration information for these modules is also lost The SCXI chassis and or SCXI module s should now be removed from the list of installed devices in MAX Removing the SCXI 1540 from a Chassis Consult the documentation for the chassis and accessories for additional instructions and precautions To remove the SCXI 1540 m
79. n to be a straight line on a plot of measured output voltage to measured input voltage with the ends of the line connecting the extremes of the plot at the full scale limits nonreferenced single ended mode all measurements are made with respect to common NRSE measurement system reference but the voltage at this reference can vary with respect to the measurement system ground the output of a system with a zero volt input G 4 ni com ppm PXI 0 quadrature encoder R resolver rms RSC RSVD RVDT S s scan National Instruments Corporation G 5 Glossary parts per million PCI eXtensions for Instrumentation an open specification that builds on the CompactPCI specification by adding instrumentation specific features A device that converts linear or rotary movement into electrical pulses on two channels The pulse stream of one channel either leads or lags the pulse stream of the other channel depending on the direction of movement A transformer based sensor for measuring absolute angular displacement over 360 Measurement is continuous for any number of revolutions The simultaneous conditioning of a sine and a cosine signal is required root mean square the square root of the average value of the square of the instantaneous signal amplitude a measure of signal amplitude rear signal connector reserved bit pin or signal rotary variable differential transformer a transformer based sensor for
80. nput signal range wire mode and external synchronization in the following ways Module property pages in MAX e Virtual channels properties in MAX e Functions in your ADE 3 Note All software configurable settings are not configurable in all three ways This section only discusses settings in MAX Refer to Chapter 4 Theory of Operation for information on using functions in your application Most of these settings are available in module properties and or using LVDT RVDT virtual channels Wire mode you can set the wire mode to either 4 or 5 wire mode as needed by your application yl Note Refer to Chapter 4 Theory of Operation for information on configuring the settings for your application using Traditional NI DAQ Legacy Configuring Module Property Pages 1 Right click the SCXI 1540 module you want to configure and select Properties Click General 2 Ifthe module you are configuring is connected to an E Series DAQ device select that device by using Connected to If you want this E Series DAQ device to control the chassis confirm there is a check in the This device will control the chassis checkbox If the module you National Instruments Corporation 3 5 SCXI 1540 User Manual Chapter 3 Configuring and Testing are configuring is not connected to an E Series DAQ device select None 3 Click the Channel tab Select the appropriate gain excitation voltage sensor wire mode excitation frequency and whethe
81. nts DA Qmx Data Acquisition subpalette and accompanying subpalettes in LabVIEW National Instruments Corporation 5 7 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 Table 5 2 Programming a Task in LabVIEW Flowchart Step VI or Program Step Create Task in DAQ Assistant Create a Task Programmatically optional Create aDAQmx Task Name Control located on the Controls All Controls I O DAQmx Name Controls subpalette right click it and select New Task DAQ Assistant DAQmx Create Task vi located on the Functions All Functions NI Measurements DA Qmx Data Acquisition DA Qmx Advanced Task Options subpalette This VI is optional if you created and configured your task using the DAQ Assistant However if you use it in LabVIEW any changes you make to the task will not be saved to atask in MAX Create LVDT or RVDT Channels DAQmx Create Virtual Channel vi AI Voltage by default to change click AI Voltage and select Analog Input Position LVDT or Analog Input Position RVDT This VI is optional if you created and configured your task and channels using the DAQ Assistant Any channels created with this VI are not saved in the DAQ Assistant They are only available for the present session of the task in LabVIEW Adjust Timing Settings optional DAQmx Timing vi Sample Clock by default This VI is optional if you created and configured your task using the DAQ Assistant Any timing
82. odule from a chassis complete the following steps while referring to Figure C 1 iyi Note Figure C 1 shows an SCXI chassis but the same steps are applicable to a PXI SCXI combination chassis National Instruments Corporation C 1 SCXI 1540 User Manual Appendix C Removing the SCXI 1540 1 Power off the chassis Do not remove the SCXI 1540 module from a chassis that is powered on 2 Ifthe SCXI 1540 15 the module cabled to the E M Series DAQ device disconnect the cable 3 Remove any terminal block that connects to the SCXI 1540 4 Rotate the thumbscrews that secure the SCXI 1540 to the chassis counterclockwise until they are loose but do not completely remove the thumbscrews Remove the SCXI 1540 by pulling steadily on both thumbscrews until the module slides completely out 1 Cable 4 LVDT Sensor 6 SCXI Chassis Power Switch 2 SCXI Module Thumbscrews 5 Terminal Block 7 SCXI Chassis 3 SOXI 1540 Figure C 1 Removing the SCXI 1540 SCXI 1540 User Manual C 2 ni com Common Questions This appendix lists common questions related to the use of the SCXI 1540 Which version of NI DAQ works with the SCXI 1540 and how do I get the most current version of NI DAQ You must have NI DAQ 7 0 or later NI recommends using the latest version of NI DAQmx Visit ni com and follow the link Drivers and Updates Current Software Versions Multifunction DAQ to find the latest version of NI DAQ for your operatin
83. og box options Bold text also denotes parameter names Italic text denotes variables emphasis a cross reference or an introduction to akey concept Italic text 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 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 Contents Chapter 1 About the SCXI 1540 What You Need to Get Started 1 1 National Instruments Documentation eese ener rennen 1 2 Installing Application Software NI DAQ and DAQ 1 4 Installing the SCXI 1540 Module into the SCXI 15 1 4 Connecting the SCXI 1540 in an SCXI Chassis to an E M Series DAQ Device for Multiplexed Scanning eene 1 4 Connecting the SCXI 1540 in a PXI SCXI Combination Chassis to E M Series DAQ Device for Multiplexed Scanning 1 4 Verifying the SCXI 1540 Installation in Software
84. ols and indicators such as charts graphs gauges slides and plots that you can use to display the data There is also a built in function found in nidagex h called NIDAQPlotWaveform that you can use to generate a simple plot of the data Other Application Documentation and Material This section provides information about multiplexed scanning and the Traditional NI DAQ Legacy examples for Measurement Studio and LabWindows CVI Refer to the ADE manual and the DAQ analog input examples that come with your application software for more detailed information on programming the SCXI modules for scanning in multiplexed mode Using Software for Multiplexed Scanning SCXI 1540 User Manual Performing scanning operations in software depends on the ADE you are using While using LabVIEW or Visual Basic 6 all scanning operations are prepared in software by using an SCXI channel string as the input to the channel parameter in the analog input VI or function These ADEs also support virtual channels using Data Neighborhood DAQ Channel Wizard in MAX In LabWindows CVI C or C development environments you need to make several NI DAQ function calls to set up each module involved in the scan the chassis and the E Series DAQ device controlling the scan A discussion describing how to implement multiplexed scanning in the different ADEs follows Refer to the ADE manual and the DAQ analog input examples that come with your application softwar
85. quisition and control interfaces inch or inches the measured resistance and capacitance between the input terminals of a circuit lowpass filter linear variable differential transformer a transformer based sensor for measuring linear displacement SCXI 1540 User Manual Glossary m mil MIO multiplexed mode N NI DAQ NI DAQmx noise nonlinearity NRSE 0 offset error SCXI 1540 User Manual meters a unit of measure equal to 0 001 inch multifunction I O an SCXI operating mode in which analog input channels are multiplexed into one module output so that your cabled E M Series DAQ device has access to the module s multiplexed output as well as the outputs of all other multiplexed modules in the chassis that are coupled to the SCXIbus National Instruments driver software for DAQ hardware The latest NI DAQ driver with new VIs functions and development tools for controlling measurement devices an undesirable electrical signal noise comes from external sources such as AC power lines motors generators transformers fluorescent lights soldering irons CRT displays computers electrical storms welders radio transmitters and internal sources such as semiconductors resistors and capacitors corrupts signals you are trying to measure for an amplifier a measure of the maximum output deviation from an ideal linear response in units of percent relative to full scale The ideal linear response is take
86. r channel Analog Input General Properties AI ACExcit WireMode Specifies the number Signal Conditioning Excitation of leads on the LVDT AC Excitation Wire Mode or RVDT Analog Input General Properties AI Gain Specifies a gain factor Advanced Gain and Offset Gain to apply to the signal Value conditioning portion of the channel Analog Input General Properties AI AutoZeroMode Specifies when to Advanced High Accuracy Settings measure ground Auto Zero Mode NI DAQmx then subtracts the voltage either on every sample or only once depending on the setting Analog Input Measurement Type AI MeasType Indicates the read only measurement to take with the analog input channel 5 Note This is not complete list of NI DAQmx properties and does not include every property you may need to configure your application It is a representative sample of important properties to configure for LVDT RVDT measurements For a complete list of NI DAQmx properties and more information about NI DAQmx properties refer to your ADE help file SCXI 1540 User Manual 5 6 ni com Chapter 5 Using the SCXI 1540 Acquiring Analyzing and Presenting After configuring the task and channels you can start the acquisition read measurements analyze the data returned and display it according to the needs of your application Typical methods of analysis include digital filtering averaging data performing harmonic analysis
87. r more advanced applications In LabVIEW an array of these channel strings configures multiple modules for scanning When using SCXI channel strings you can scan up to 3 072 channels in a multichassis system using a single E Series DAQ device Refer to Appendix B Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later for more information about using SCXI channel strings 3 Note You cannot mix virtual channels with the SCXI channel strings within the same channel string array To use virtual channels enter the name of a virtual channel into the analog input channel string If using multiple virtual channels enter them in a different index in the channel string array or separate them using a comma Since you can randomly scan analog input virtual channels you can enter the virtual channels you want to scan in any order or repeatedly in a channel string array National Instruments Corporation 5 15 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 SCXI 1540 User Manual Typical Program Flow After you have determined how you want to address the channels and whether you want to configure the SCXI 1540 in MAX or LabVIEW you can design your application using a typical program flow such as the one shown in Figure 5 4 Use Virtual Channel or SCXI Channel String Virtual Channel SCXI Channel String Configure y Acquisition Settings Create Virtual Channel in MAX Configur
88. r or not you want to use external synchronization for each channel If you want to configure all the channels at the same time select the Channel drop down menu scroll to the bottom and select Channels Refer to the Common Software Configurable Settings section for a detailed description of each setting Click Apply 4 Click Accessory Select the accessory you connected to the module When configuration is complete click OK The Traditional NI DAQ Legacy chassis and SCXI 1540 should now be configured properly If you need to change the module configuration right click the module and repeat steps 1 through 4 Test the system following the steps in the Troubleshooting the Self Test Verification section of Chapter 1 About the SCXI 1540 Creating an LVDT RVDT Virtual Channel To create an LVDT RVDT virtual channel complete the following steps Right click Data Neighborhood and select Create New Select Traditional NI DAQ Virtual Channel and click Finish Select Analog Input from the drop down menu and click Next Enter the Channel Name and Channel Description and click Next Select LVDT RVDT from the drop down menu and click Next Enter the following information Quod sm cU a Physical unit b Sensitivities unit from the drop down menu c Sensitivity d Measurement range min and max 7 Click Next Enter the following information a What DAQ hardware will be used from the drop down menu b What channel on your DAQ
89. r s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire flood 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 mechanical 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 Trademarks National Instruments NI ni com and LabVIEW are trademarks of National Instruments Corporation Refer to the Terms of Use section on ni com 1egal for more information about National Instruments trademarks Other product and company names mentioned herein are trademarks or trade names of their respective companies Patents For patents covering National Instruments products refer to the appropriate location Help Patents in your software the patents txt file on your CD or ni com patents 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 T
90. reserved Important Information Warranty The SCXI 1540 is warranted against defects in materials and workmanship for a period of one year from the date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace equipment that proves to be defective during the warranty period This warranty includes parts and labor 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
91. rimary Secondary SUEDE Cum 22 Ee Output Signal Secondary Primary Secondary Output Signal E OUT Core at Center Core Left of Center Core Right of Center National Instruments Corporation Figure 4 2 LVDT Core Locations with Resulting Induced Voltage and Phase 4 3 SCXI 1540 User Manual Chapter 4 Theory of Operation LVDTs are frequently used in applications where ruggedness operation over large temperature ranges insensitivity to contamination or long life are important considerations They are extremely reliable in harsh conditions An RVDT is simply the rotational version of an LVDT The angular measurement range of typical RVDTs is between x30 and 70 Resolvers are similar to RVDTs but employ secondaries at right angles that produce two simultaneous signal voltages proportional to the sine and cosine of the shaft angle Thus resolvers can measure over 360 of rotation and do not need to pass through 0 before making absolute position measurements as is required by quadrature encoders Like LVDTs and RVDTs resolvers are advantageous in hostile operating environments Resolvers are often easier to use than RVDTs You can originate the 0 position arbitrarily in software without the need to physically rotate the sensor into position Sinc
92. settings modified with this VI are not saved in the DAQ Assistant They are only available for the present session of the task in LabVIEW Configure Channels optional DAQmx Channel Property Node refer to the Using a DAQmx Channel Property Node in LabVIEW section for more information This step is optional if you created and fully configured the channels using the DAQ Assistant Any channel modifications made with a channel property node are not saved in the task in the DAQ Assistant They are only available for the present session of the task in LabVIEW Start Measurement DAQmx Start Task vi Read Measurement Analyze Data DAQmx Read vi Some examples of data analysis include filtering scaling harmonic analysis or level checking Some data analysis tools are located on the Functions Signal Analysis subpalette and on the Functions All Functions Analyze subpalette SCXI 1540 User Manual 5 8 ni com Chapter 5 Using the SCXI 1540 Table 5 2 Programming a Task in LabVIEW Continued Flowchart Step VI or Program Step Display Data You can use graphical tools such as charts gauges and graphs to display your data Some display tools are located on the Controls Controls Numeric Numeric Indicators subpalette and Controls Controls Graph subpalette Continue Sampling For continuous sampling use a While Loop If you are using hardware timing you also need to s
93. signal terminals are disconnected The excitation terminals remain connected to the front panel This causes no problems during calibration provided there is no wiring error that might short circuit the excitation signal Caution Ensure the calibration on the DAQ device or DMM you are using is current and traceable If you modify the gain and offset software correction values using an uncalibrated device your calibration is not valid or your calibration is not traceable SCXI 1540 User Manual 5 28 ni com Chapter 5 Using the SCXI 1540 Calibration Using LabVIEW or a C Based ADE You can use the LabVIEW SCXI Calibrate VI or the NI DAQ function SCXI Calibrate to calibrate your SCXI 1540 These functions calibrate all channels for all gains and excitation levels when called If you are using external synchronization National Instruments recommends that you perform a calibration with the synchronization wiring and synchronization configuration settings in place Excitation levels and frequencies are affected slightly by synchronization which in turn slightly effects the calibration If you are using LabVIEW use the following procedure 1 Make sure the E M Series DAQ device or DMM you are using has a valid calibration 2 Use the LabVIEW function SCXI Calibrate VI to calibrate your module a Enter the E M Series DAQ device and the SCXI channel string for all eight channels For example your channel string might be scl
94. storing the channel scan list defined in your application code NI DAQ drivers load the FIFO based on the channel assignments you make in your application You need not explicitly program the module FIFO as this is done automatically for you by the NI DAQ driver When you configure a module for multiplexed mode operation the routing of multiplexed signals to the E M Series DAQ device depends on which module in the SCXI system is cabled to the E M Series DAQ device There are several possible scenarios for routing signals from the multiplexed modules to the E M Series DAQ device If the scanned SCXI 1540 module is not directly cabled to the E M Series DAQ device the module sends its signals through the SCXIbus to the cabled module The cabled module whose routing is controlled by the SCXI chassis routes the SCXIbus signals to the E M Series DAQ device through the CH 0 pin on its rear signal connector If the E M Series DAQ device scans the cabled module the module routes its input signals through the CH 0 pin on its rear signal connector to the E M Series DAQ device CH 0 Multiplexed mode scanning acquisition rates have limitations that are determined based on the hardware in the system and the mode of operation The maximum multiplexing rate of SCXI is 333 KHz If the E M Series DAQ device can sample more quickly than 333 kHz then the maximum multiplexing rate of SCXTis the limiting factor If the E M Series DAQ device cannot sample at 33
95. tant or Programmatically When creating an application you must first decide whether to create the appropriate task using the DAQ Assistant or programmatically in the ADE Developing your application using DAQ Assistant gives you the ability to configure most settings such as measurement type selection of channels excitation voltage signal input limits task timing and task triggering You can access the DAQ Assistant through MAX or your NI ADE Choosing to use the DAQ Assistant can simplify the development of your application NI recommends creating tasks using the DAQ Assistant for ease of use when using a sensor that requires complex scaling or when many properties differ between channels in the same task If you are using an ADE other than an NI ADE or if you want to explicitly create and configure a task for a certain type of acquisition you can programmatically create the task from your ADE using functions or VIs If you create a task using the DAQ Assistant you can still further configure the individual properties of the task programmatically with functions or property nodes in your ADE NI recommends creating a task programmatically if you need explicit control of programmatically adjustable properties of the DAQ system Programmatically adjusting properties for a task created in the DAQ Assistant overrides the original or default settings only for that session The changes are not saved to the task configuration The next tim
96. the task that you can set or edit using DAQmx Property Nodes How do I control the gain frequency excitation level wire mode and synchronization in C based application environments You must use the NI DAQ functions listed in Table 5 5 NI DAQ Functions Used to Configure SCXI 1540 D 4 ni com Glossary Symbol Prefix Value p pico 10772 n nano 1079 u micro 10 6 m milli 10 3 k kilo 103 Numbers Symbols percent per E degrees Q ohms 5 V signal 5 VDC source signal A A amperes absolute accuracy the maximum difference between the measured value from a data acquisition device and the true voltage applied to the input typically specified as voltage AC alternating current ADE application development environment such as LabVIEW LabWindows CVI Visual Basic 6 C and C AI HOLD COMP scan clock signal used to increment to the next channel after each AI HOLD E M Series DAQ device analog to digital conversion National Instruments Corporation G 1 SCXI 1540 User Manual Glossary C C CE CH x crosstalk DAQ DAQ device DC DIGGND DIN DIO DMM E EEPROM EMC SCXI 1540 User Manual Celsius European emissions control standard negative input terminal for channel x positive input terminal for channel x an unwanted signal on one channel due to an input signal on a different channel data acquisition 1 collecting and measuring
97. ting with 1 channel is the channel that is sampled from module z Use the format obx scy mdz n to verify the signal where n is a single input channel Complete the following steps to use channel strings in verifying the signal 1 o SCXI 1540 User Manual Expand the list of tasks and virtual channels by clicking the next to Devices and Interfaces Click the next to Traditional NI DAQ Devices to expand the device list Right click the appropriate E Series DAQ device Click Test Panels Enter the channel string Enter the input limits 3 8 ni com Chapter 3 Configuring and Testing 7 Select the Data Mode 8 Select the Y Scale Mode Refer to the LabVIEW Measurements Manual for more information and for proper formatting of channel strings for different uses Verifying the Signal Using LVDT RVDT Virtual Channel If you have already created a virtual channel complete the following steps to verify the signal 1 Right click the virtual channel you want to verify and select Test 2 In Channel Names select the channel you want to verify 3 When you have completed verifying the channel click Close National Instruments Corporation 3 9 SCXI 1540 User Manual Theory of Operation This chapter discusses LVDT RVDT resolver concepts and the SCXI 1540 LVDTs RVDTs and Resolvers An LVDT is a device for measuring linear position Figure 4 1 shows a cut away view of an LVDT
98. tion on the desktop 2 Right click Data Neighborhood and select Create New 3 Select NI DAQmx Task NI DAQmx Global Channel and click Next Select Analog Input Select Position Select LVDT or RVDT If you are creating a task you can select a range of channels by holding down the Shift key while selecting the channels You can select multiple individual channels by holding down the Ctrl key while selecting channels If you are creating a channel you can only select one channel Click Next p gu Ut od 8 Name the task or channel and click Finish 3 4 ni com Chapter 3 Configuring and Testing 9 Inthe Channel List box select the channel s you want to configure You can select a range of channels by holding down the Shift key while selecting the channels You can select multiple individual channels by holding down the Ctrl key while selecting channels 10 Enter the specific values for your application in the Settings tab Context help information for each setting is provided on the right side of the screen 11 Click the Device tab and select the autozero mode and whether or not you want synchronization enabled 12 If you are creating a task and want to set timing or triggering controls enter the values in the Task Timing and Task Triggering tabs Traditional NI DAQ Legacy In Traditional NI DAQ Legacy you can configure software settings such as voltage excitation level and frequency gain i
99. tional code Virtual channels are particularly useful when sensors requiring different scaling factors are used on the same SCXI 1540 channel Using virtual channels you can use sensors needing special scaling in a generic analog input application without performing hard coded scaling If you change the scaling or want to connect a different sensor to your SCXI 1540 no changes are needed in the application All that is required is creating a different virtual channel and using its name in the channel string 3 Note You cannot mix virtual channels with the SCXI channel strings shown in the previous section To create a virtual channel for the SCXI 1540 insert a new analog input channel in the Data Neighborhood path in MAX name it and then follow the software prompts to create virtual position channels voltage channels or customized analog input channels For more information on virtual channels consult the MAX online help file To use virtual channels enter the name of a virtual channel into the analog input channel string If using multiple virtual channels separate them using a comma or enter them in a different index in the channel string array AII scaling is done automatically by the application 3 Note Since you can randomly scan virtual analog input channels you can enter virtual channels in any order or repeatedly in the channel string Performing a Multiplexed Scan SCXI 1540 User Manual To perform a multiplexed scan in
100. to configure and use NI DAQmx to control the SCXI 1540 in LabVIEW LabWindows CVI and Measurement Studio These ADEs provide greater flexibility and access to more settings than MAX but you can use ADEs in conjunction with MAX to quickly create a customized application Typical Program Flowchart Figure 5 1 shows a typical program LVDT RVDT flowchart for creating a task to configure channels take a measurement analyze the data present the data stop the measurement and clear the task Figure 5 2 shows a similar flowchart for a resolver National Instruments Corporation 5 1 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 Yes Create Task Using No DAQ Assistant Y y Create a Task Programmatically Create LVDT or RVDT Channel Hardware Timing Triggering Create Task in DAQ Assistant or MAX Create Another Channel Further Configure Channels Yes Adjust Timing Settings y Configure Channels Analyze Data ra Process No Data Yes y Start Measurement Display Data Graphical Read Measurement Display Tools A Yes Continue Sampling Stop Measurement Y Clear Task Figure 5 1 Typical Program Flowchart for LVDT or RVDT Channels SCXI 1540 User Manual 5 2 ni com Chapter 5 Using the SCXI 1540 Create a Task Programmatica
101. ts 1 0 System Double AISensitivityUnits MVolts Volt 0 001inch AISensitivityUnits sensitivityUnits AIExcitationSourceInternal AIExcitationSource voltExcitSource 1 0 System Double voltExcitUnit 2500 System Double voltExcitFreq ATACExcitWireMode 4Wire AIACExcitWireMode acExcitWireMode setting attributes after the channel is created AIChannel myChannel myTask AIChannels LVDT0 myChannel AutoZeroMode ATAutoZeroMode Once You can change any of the properties at a later time For example to change the excitation value of myChannel enter the following lines AIChannel myChannel myTask AIChannels LVDT 0 myChannel Excitationvalue 3 0 Modify the example code above or the code from one of the shipping examples as needed to suit your application Refer to the Other Application Documentation and Material section for the location of program examples Notes You can create and configure LVDT RVDT task MAX and load it into your application with the function call NationalInstruments DAQmx DaqSystem Local LoadTask Refer to the NI Measurement Studio Help for more information on creating NI DAQmx tasks in LabWindows CVI and NI DAQmx property information National Instruments Corporation 5 13 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 Programmable NI DAQmx Properties All of the different ADEs that configure the SCXI 1540 access underlying set of N
102. uency SCXI Set Excitation Excitation Level SCXI Set Excitation Wire Mode 4 Wire or 5 Wire SCXI Configure Connection Enable External Synchronization SCXI Configure Connection 2 Specify the module scan list the start channel of each module and the number of channels to scan on each module with the function SCXI SCAN Setup This function accepts an array of start channels and an array of the number of channels to scan in each module Therefore it is not possible to repeat channels or use nonsequential channels using this function 3 Use SCXI_MuxCtr_Setup to program the E Series DAQ device with the correct number of channels multiplexed per scan This number must match the total number of channels programmed in step 2 You are now ready to acquire the channel data with the E Series DAQ device If you are using a multifunction E Series DAQ device you can use SCAN Op to perform the scanning operation After scanning convert the binary data to voltage data using 5 Scale Refer to the Traditional NI DAQ Legacy User Manual for additional information on scanning with E Series DAQ devices National Instruments Corporation 5 27 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 Traditional NI DAQ Legacy CVI Examples Many example programs ship with NI DAQ For more example information on how to create tasks and channels refer to the example programs By default the example programs are installed in v Program Files Nat
103. ut position change for a primary excitation level of one volt rms serial data output signal the manipulation of signals to prepare them for digitizing synchronization pulse for scanning a measure of the amount of noise seen by an analog circuit or an ADC when the analog inputs are grounded An upgrade to the earlier version of NI DAQ Traditional NI DAQ Legacy has the same VIs and functions and works the same way as NI DAQ 6 9 x You can use both Traditional NI DAQ Legacy and NI DAQmx on the same computer which is not possible with NI DAQ 6 9 x Underwriters Laboratory G 6 ni com VDC VI virtual channels V rms W working voltage Glossary volts volts direct current virtual instrument 1 a combination of hardware and or software elements typically used with a PC that has the functionality of a classic stand alone instrument 2 a LabVIEW software module VI which consists of a front panel user interface and a block diagram program channel names that can be defined outside the application and used without having to perform scaling operations volts root mean square the highest voltage with respect to ground that should be applied to an input terminal during normal use normally well under the breakdown voltage for safety margin Includes both the signal and common mode voltages National Instruments Corporation G 7 SCXI 1540 User Manual Index A accessories for connecting signals D
104. vel SCXI AC Voltage Excitation Float In dbl 1 0 3 0 Excitation SCXI AC Frequency Excitation Float In dbl 2500 3300 5000 10000 Frequency Connection Type SCXI Connection Type Value In 4 Wire LVDT 5 Wire LVDT Synchronization SCXI Synchronization Type Value In Internal Synchronization Type External Synchronization National Instruments Corporation 5 17 SCXI 1540 User Manual Chapter 5 Using the SCXI 1540 An example of using the AI Parameter VI to control an SCXI 1540 is shown in Figure 5 5 input limits no change Allowable rms voltage values Allowable excitation frequency values 1 0 3 0 2500 0 3300 0 5000 0 10000 0 DBE SCXI AC Voltage Excitation SEXI AC Frequency Excitation Allowable connection types Allowable connection types 4 Wire LVDT 5 Wire LVDT Internal Synchronization External Synchronization 4 Wire LVDT ntemal Synchronization v SEXI Connection Type CX Synchronization Type Figure 5 5 Using the Al Parameter VI to Set Up the SCXI 1540 SCXI 1540 User Manual 5 18 ni com Chapter 5 Using the SCXI 1540 Configure Start Acquisition and Take Readings Using Traditional NI DAQ Legacy in LabVIEW After you have configured the SCXI 1540 settings for your application you can use the intermediate analog input functions AI Config VI AI Start VI AI Read VI and AI Clear VI to create your
105. you can set the properties of the channels programmatically using the DAQmx Channel Property Node 5 10 ni com Chapter 5 Using the SCXI 1540 Follow the general programming flowchart or open an example to build a basic LVDT RVDT virtual channel You can use property nodes in LabVIEW to control configure and customize the NI DAQmx task and SCXI 1540 To create a LabVIEW property node complete the following steps 1 Launch LabVIEW 2 Create the property node in a new Virtual Instrument VI or in an existing VI Open the block diagram view From the Functions tool bar select NI Measurements DAQmx Data Acquisition and select the type of property node you wish to configure Left click inside the property box and select ActiveChans This allows you to specify what channel s you want to configure If you want to configure several channels with different properties separate the lists of properties with another ActiveChans box and assign the appropriate channel to each list of properties Right click ActiveChans and select Add Element Left click the new ActiveChans box Navigate through the menus and select the property you wish to define You must change the property to read or write to either get the property or write a new value Right click the property go to Change To and select Write Read or Default Value After you have added the property to the property node right click the terminal to change the attributes of
106. you to take measurements from several channels on one module with only one channel string entry An array of these channel string entries configures multiple modules for scanning When the application program runs the channel string is used for programming the channel information into the SCXI system The format of the channel string is as follows obx scy mdz channels where obx is the onboard E Series DAQ device channel with x representing a particular channel where the multiplexed channels are sent This value is 0 for E Series DAQ device channel 0 in a single chassis system In a multichassis or remote chassis system the E Series DAQ device channel x corresponds to chassis number n 1 where E Series DAQ device channel xis used for scanning the nth chassis in the system scy is the SCXI chassis ID where yis the number you chose when configuring the chassis mdz is the slot position where the module is located with z being the particular slot number The slots in a chassis are numbered from left to right starting with 1 National Instruments Corporation B 1 SCXI 1540 User Manual Appendix B Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later channels is the list of channels that are scanned for module z It can have several formats scy mdz nx where nxis a single input channel scy mdz n0 2 n0 n2 individual input channel that are not necessar
107. your application complete the following steps 1 Open an analog input example in your ADE 2 Enter the appropriate SCXI channel string or virtual channel string into the channels parameter 3 Either enter the input limits for signals connected to your module to adjust the gain settings in your system or use the default gain settings from the configuration utility and then run the application When using virtual channels the default input limits configured in the virtual channel configurator are used 5 26 ni com Chapter 5 Using the SCXI 1540 You have completed a multiplexed scan using your SCXI 1540 This is not a comprehensive discussion of SCXI scanning using LabVIEW and Visual Basic but this should give you enough information to help you get started with the examples shipped with these software packages C and Low Level DAQ Functions When using a C based environment you need to take several steps to configure the SCXI 1540 for multiplexed scanning The following procedure outlines the steps for programming with the low level NI DAQ function calls 1 Prepare your SCXI 1540 settings either by loading the original SCXI configuration settings using 5 Load Config or by specifying all configuration settings using the NI DAQ function calls in Table 5 6 Table 5 6 NI DAQ Functions Used to Configure SCXI 1540 Channel Setting NI DAQ Function to Use Gain SCXI Set Gain Excitation Freq

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