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NI-DNET Programmer Reference Manual

1. Attribute ID NC_ATTR_KEEP_EXPL_MSG Hex Encoding 80000099 Data Type NCTYPE_BOOL Permissions Set Description To properly close I O connections in the remote device when ncCloseObject is called NI DNET must ensure that an explicit messaging connection to the device remains open When this attribute is set to NC_TRUE the default NI DNET sends a nonoperational request a ping to the device every few seconds to ensure that the explicit messaging connection does not timeout When this attribute is NC_FALSE NI DNET does not ping the explicit messaging connection If you are certain that your device can internally close its own I O connections deferred delete you can set this attribute to NC_FALSE This attribute must be set prior to starting communication Mac Id Attribute ID NC_ATTR_MAC_ID Hex Encoding 80000080 Data Type NCTYPE_UINT8 Permissions Get Description This driver attribute allows you to get the DeviceMacId originally passed into ncOpenDnet Io Output Length Attribute ID NC_ATTR_OUT_LEN Hex Encoding 80000092 Data Type NCTYPE_UINT32 Permissions Get Description This driver attribute allows you to get the OutputLength originally passed into ncOpenDnet Io National Instruments Corporation 3 13 NI DNET Programmer Reference Manual Chapter 3 NI DNET Programmer Reference Manual NI DNET Objects 1 0 Object
2. Start Start all DeviceNet communication for the associated interface For each Explicit Messaging Object and I O Object which has been opened for the interface same Int fName this operation establishes the DeviceNet connection with the remote device When the operation establishes I O connections it places outputs into active mode data is produced on the network If the default output data all bytes zero is not valid for your application use ncWriteDnetIo for each I O Object to initialize valid output data prior to starting communication If the interface has already been started this operation has no effect Stop Stop all DeviceNet communication for the associated interface For each Explicit Messaging Object and I O Object which has been opened for the interface this operation closes the DeviceNet connection with the remote device Although closing all NI DNET objects implicitly stops communication you should perform this operation prior to calling ncCloseObject If the interface has already been stopped this operation has no effect Active Place the outputs of all I O connections into active mode When an I O connection is in active mode it produces data in its outgoing T O message This operation is used after a previous Idle to restore normal communication on all I O Objects associated with the interface If the interface has already been placed into active mode or is stopped this operation has no effect
3. Description Actual number of service data bytes in response This length is obtained from the actual response message If this length is greater than SizeofServData only SizeofServData bytes are returned in ServData If this length is less than or equal to SizeofServData ActualServDataLength bytes are valid in ServData Values 0 to 240 Examples LabVIEW Read an explicit message response from an Explicit Messaging Object ObjiHandie in ObsHandle out 4ctualServD ataLength Error out Error in C Read an explicit message response from the Explicit Messaging Object referenced by objh NCTYPE_STATUS status NCTYPE_OBJH objh NCTYPE_UINT8 servcode NCTYPE_UINT8 servdata 20 NCTYPE_UINT16 actual_len status ncReadDnetExplMsg objh amp servcode 20 servdata amp actual_len National Instruments Corporation 2 71 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncReadDnetlO Read DeviceNet 1 0 ncReadDnetlO Read DeviceNet 1 0 Purpose Read input data from an I O Object Format LabVIEW ObjHandle in ObjHandle out Data Error in Error out C NCTYPE_STATUS ncReadDnet 10 NCTYPE_OBJH ObjHandle NCTYPE_UINT32 SizeofData NCTYPE_ANY_P Data Input ObjHandle Object handle of an open I O Object SizeofData Size of Data buffer in bytes C only Output Data Input data Function Description ncReadDnet 10 reads input data from an NI DNET I O Obj
4. DnetData out Description DeviceNet data bytes unchanged The data bytes of DnetData inare passed through the VI to this output terminal unchanged To convert another DeviceNet data member this data can be passed on to another call to this function Values Same as DnetData in 8 TF out Description If the selected Dnet Type is BOOL this output terminal provides the converted DeviceNet data member The LabVIEW data type for this output terminal is an array of eight LabVIEW Booleans indicated as 8 TF You can index into this array to use specific Boolean members The Boolean at index zero is the least significant bit bit 0 the Boolean at index one is the next least significant bit 1 and so on Values Converted DeviceNet data member National Instruments Corporation 2 23 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncConvertFromDnetRead Convert From DeviceNet Read 132 116 18 out Description If the selected Dnet Type is SINT INT or DINT this output terminal provides the converted DeviceNet data member Although the LabVIEW data type for this output terminal is 132 it can be coerced automatically to 116 or 18 Values Converted DeviceNet data member U32 U16 U8 out Description If the selected Dnet Type is USINT UINT or UDINT this output terminal provides the converted DeviceNet dat
5. Values Same as the ServiceCode of ncWriteDnetExp1Msg success response or 14 hex error response SizeofServData Description For C this is the size of the buffer referenced by ServData Use it to verify that you have enough bytes available to store the service data from the response This size is normally obtained using the C language sizeof function and has no direct relation to the number of bytes received on the network For LabVIEW since the buffer for ServData is allocated automatically by NI DNET this size is not needed The number of bytes allocated for ServData should be large enough to hold the maximum number of service data response bytes defined for the service Values sizeof buffer referenced by ServData NI DNET Programmer Reference Manual 2 70 ni com Chapter 2 NI DNET Functions ncReadDnetExpiMsg Read DeviceNet Explicit Message ServData Description Service data bytes from response If the response is success these bytes are formatted as defined by the service If the response is error the first byte ServData 0 contains a General Error Code and the second byte ServData 1 contains an Additional Code Either the DeviceNet Specification or the object itself define the error codes The number of service data bytes returned is the smaller of SizeofServData and ActualServDataLength Values Service data bytes from response ActualServDataLength
6. Purpose Close multiple NI DNET objects in one call Format LabVIEW Interface ObjHandle In Device ObjHandle In Error In C Not applicable Input Interface ObjHandle In Object handle of an open Interface Object returned from either Easy IO Config or Open DeviceNet Interface function Device ObjHandle In Atray of I O and or Explicit Messaging object handles Error in NI DNET Error Cluster input Output Error out NI DNET Error Cluster output Function Description Easy10Close stops the Interface Object closes all the object handles passed in the Device ObjHandle In parameter and then closes the Interface Object You normally call EasyI0Close near the end of your application to ensure that all objects are properly deallocated EasylO0Close accepts Interface ObjHandle In and Device ObjHandle In as input parameters You pass the outputs from EasyIOConfig as inputs to EasyIOClose Internally the Easy10C1lose function makes use of OperateDeviceNetInterface vi ncOperateDnetIntf and CloseObject vi ncCloseObject To learn more about these functions refer to the corresponding function description sections NI DNET Programmer Reference Manual 2 4 ni com Chapter 2 NI DNET Functions EasylOClose Easy 10 Close Parameter Descriptions Interface ObjHandle In Description Contains an interface object handle returned from the Easy IO Config or Open DeviceNet Interface function Values The encoding of object handle i
7. ncCloseObject Close an NI DNET object ncGetDriverAttr Get the value of an attribute in the NI DNET driver ncOpenDnetInt f Configure and open an NI DNET Interface Object ncOperateDnetIntf Perform an operation on an NI DNET Interface Object ncSetDriverAttr Set the value of an attribute in the NI DNET driver ncStatusToString Convert status returned from an NI DNET function into a descriptive string C only NI DNET Programmer Reference Manual 3 6 ni com Chapter 3 NI DNET Objects Interface Object Driver Attributes Baud Rate Attribute ID NC_ATTR_ BAUD_ RATE Hex Encoding 80000007 Data Type NCTYPE_BAUD_ RATE Permissions Get Description This driver attribute allows you to get the BaudRate originally passed into ncOpenDnetIntf Interface Protocol Version Attribute ID NC_ATTR_PROTOCOL_VERSION Hex Encoding 80000002 Data Type NCTYPE_VERSION Permissions Get Description This driver attribute reports the version of the DeviceNet Specification to which the NI DNET software conforms This version is at least 02000000 hex version 2 0 Interface Software Version Attribute ID NC_ATTR_SOFTWARE_VERSION Hex Encoding 80000003 Data Type NCTYPE_VERSION Permissions Get Description This driver attribute reports the version of the NI DNET software This version is at least 01000000 hex version 1 0 National Instruments Corporation 3 7 NI
8. A classification of things with similar qualities NI DNET Programmer Reference Manual Glossary connection controller COS I O cyclic I O D device device network DeviceNet interface E expected packet rate explicit messaging connection H hex An association between two or more devices on a network that describes when and how data is transferred A device that receives data from sensors and sends data to actuators to hold one or more external real world variables at a certain level or condition A thermostat is a simple example of a controller See change of state I O Master slave I O connection in which the slave or master sends data at a fixed interval A physical assembly linked to a communication line cable capable of communicating across the network according to a protocol specification Multi drop digital communication network for sensors actuators and controllers A physical DeviceNet port on an AT CAN PCI CAN PCMCIA CAN or PXI 8461 interface The rate in milliseconds at which a DeviceNet connection is expected to transfer its data General purpose connection used for executing services on a particular object in a DeviceNet device Hexadecimal NI DNET Programmer Reference Manual G 2 ni com T O connection individual polling instance L LabVIEW local MAC ID master slave member method multi drop National Instruments Corporation G 3
9. Values 0 to 240 National Instruments Corporation 2 39 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncGetDnetAttribute Get DeviceNet Attribute DeviceError Description Error codes from device s error response If the remote device responds successfully to the Get Attribute Single service the return status is 0 Dnet Success and DeviceError returns 0 If the remote device returns an error response for the Get Attribute Single service the return status is BFF62014 hex DnetErrErrorResponse and DeviceError returns the error codes from the response The General Error Code from the device s error response is returned in the low byte of DeviceError Common values for General Error Code include Attribute Not Supported 14 hex Object Does Not Exist 16 hex and Invalid Attribute Value 09 hex The Additional Code from the device s error response is returned in the high byte of DeviceError The Additional Code provides additional information that further describes the error If no additional information is needed the value FF hex is placed into this field Values for the General Error Code and Additional Code are documented in the DeviceNet Specification Common error code values are found in Appendix H DeviceNet Error Codes in the DeviceNet Specification Object specific error codes are listed in the object description Vendor specific error codes are listed in your d
10. ncCreateNotitication Create Notification Callback Continued Values Address of a callback function within your application source code For example if your function is declared with the name MyReadCallback you would pass MyReadCallback as the Callback parameter Example C Create a notification for the ReadAvail state Use a timeout of 10 seconds NCTYPE_UINT8 DataBuffer 20 NCTYPE_STATE _NCFUNC_ MyReadCallback T NCTYPE_OBJH ObjHandle NCTYPI Gl _STATE CurrentState NCTYP CI STATUS Status NCTYPE_ANY_P RefData if Status DnetSuccess Status ncReadDnetIO ObjHandle 20 RefData return NC_ST_READ_ AVAIL NI DNET Programmer Reference Manual 2 34 ni com Chapter 2 NI DNET Functions ncCreateNotification Create Notification void main NCTYPE_STATUS status NCTYPE_OBJH objh status ncCreateNotification objh NC_ST_READ AVAIL 10000 DataBuffer MyReadCallback National Instruments Corporation 2 35 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncGetDnetAttribute Get DeviceNet Attribute ncGetDnetAttribute Get DeviceNet Attribute Purpose Get an attribute value from a DeviceNet device using an Explicit Messaging Object Format LabVIEW Timeout DeviceError ObjHandle in ObjHandle out Classld AttrData Instanceld Actual4ttrD ataLenagth Attributeld Error out Error i
11. Chapter 2 NI DNET Functions ncOpenDnetintf Open DeviceNet Interface Examples LabVIEW Open Interface Object DNET1 using baud rate 500000 MAC ID 3 and poll mode Scanned ObsHandile out Interface Name d s Error out DeviceNet Network Interface Config Cluster C Open Interface Object DNETO using baud rate 125000 MAC ID 0 and poll mode Automatic NCTYPE_STATUS status NCTYPE_OBJH objh status ncOpenDnetIntf DNETO 0 125000 NC_POLL_AUTO amp objh National Instruments Corporation 2 53 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetlO Open DeviceNet 1 0 ncOpenDnetlO Open DeviceNet 1 0 Purpose Configure and open an NI DNET I O Object Format LabVIEW Interface Name ObjHandle out DeviceNet 10 Connection Configuration Cluster Error out Error in C NCTYPE_STATUS ncOpenDnetIoO NCTYPE_STRING IntfName NCTYPE_UINT32 DeviceMacId NCTYPE_UINT32 ConnectionType NCTYPE_UINT32 InputLength NCTYPE_UINT32 OutputLength NCTYPE_UINT32 ExpPacketRate NCTYPE_OBJH_P ObjHandle Input Int Name Name of DeviceNet interface DeviceMacId MAC ID of the remote device ConnectionType Type of I O connection InputLength Number of input bytes OutputLength Number of output bytes ExpPacketRate Expected rate of I O message packet production Output ObjHandle Object handle you use with all subsequent function calls for the I O Object NI DNET Programmer Ref
12. Glossary Connection used for exchange of physical input output sensor activator data as well as other control oriented data A polled I O communication scheme in which each polled slave communicates at its own individual rate A specific instance of a given class For example a blue square of 4 inches per side would be one instance of the class Geometric Shapes Kilobytes of memory Laboratory Virtual Instrument Engineering Workbench Within NI DNET anything that exists on the same host personal computer as the NI DNET driver Media access control layer identifier In DeviceNet a device s MAC ID represents its address on the DeviceNet network DeviceNet communication scheme in which a master device allocates connections to one or more slave devices and those slave devices can only communicate with the master and not one another An individual data value within an array of DeviceNet data bytes An action performed on an instance to affect its behavior the externally visible code of an object Within NI DNET you use NI DNET functions to execute methods for objects Also known as service operation and action A physical connection in which multiple devices communicate with one another along a single cable NI DNET Programmer Reference Manual Glossary NI DNET driver notification object ODVA P polled I O protocol R remote resource Device driver and or firmware that implement all the
13. I O Object 3 9 instrument drivers NI resources A 1 Interface Object 3 6 K KnowledgeBase A 1 National Instruments support and services A 1 ncCloseObject 2 10 ncConvertForDnetWrite 2 12 ncConvertFromDnetRead 2 20 ncCreateNotification 2 27 ncGetDnetAttribute 2 36 ncGetDriverAttr 2 42 ncOpenDnetExpIMsg 2 45 ncOpenDnetIntf 2 48 ncOpenDnetlO 2 54 ncOperateDnetIntf 2 64 ncReadDnetExpIMsg 2 68 ncReadDnetlO 2 72 ncSetDnetAttribute 2 75 ncSetDriverAttr 2 80 ncStatusToString 2 83 NCTYPE_ANY_P 1 2 NCTYPE_ATTRID 1 2 NCTYPE_BOOL 1 1 NCTYPE_DURATION 1 2 NCTYPE_INT16 1 1 NCTYPE_INT32 1 1 NCTYPE_INTS8 1 1 NCTYPE_LREAL 1 1 NCTYPE_OBJH 1 2 NCTYPE_OPCODE 1 3 NCTYPE_REAL 1 1 NCTYPE_STATE 1 3 NI DNET Programmer Reference Manual 1 2 NCTYPE_STATUS 1 3 NCTYPE_STRING 1 1 NCTYPE_type_P 1 1 NCTYPE_UINT16 1 1 NCTYPE_UINT32 1 1 NCTYPE_UINTS 1 1 NCTYPE_VERSION 1 2 ncWaitForState 2 86 ncWriteDnetExplMspg 2 91 ncWriteDnetIO 2 95 NI support and services A 1 NI DNET data types 1 1 functions 2 1 descriptions using 2 1 EasyIOClose 2 4 EasylOConfig 2 6 list of 2 2 ncCloseObject 2 10 ncConvertForDnetWrite 2 12 ncConvertFromDnetRead 2 20 ncCreateNotification 2 27 ncGetDnetAttribute 2 36 ncGetDriverAttr 2 42 ncOpenDnetExpIMsg 2 45 ncOpenDnetIntf 2 48 ncOpenDnetlO 2 54 ncOperateDnetIntf 2 64 ncReadDnetExplMs 2 68 ncReadDnetIlO 2 72 ncSetDnetAttribute 2 75 ncSetDriverAttr
14. National Instruments Corporation 2 65 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOperateDnetintf Operate DeviceNet Interface Opcode Continued Description Idle Continued Place the outputs of all I O connections into the idle mode When an I O connection is in the idle mode it does not produce data in its outgoing I O message but the I O connection is kept open by producing an I O message with zero data bytes Use this operation when valid output data is no longer available from your application such as when a control algorithm has been paused If the interface has already been placed into idle mode or is stopped this operation has no effect Note The DeviceNet Specification does not clearly define the behavior of a slave device on reception of an idle zero length I O message Many slave devices exhibit unexpected behavior when the Idle operation is used If you need to suspend your application but want to keep I O connections open you should provide valid idle values for outputs using ncWriteDnet1I0 rather than use the Idle operation Values Start constant NC_OP_START value 1 Stop constant NC_OP_STOP value 2 Active constant NC_OP_ACTIVE value 4 Idle constant NC_OP_IDLE value 5 In LabVIEW you select the operation code from an enumerated list The LabWindows CVI function panel also provides an enumerated list Param Description The meaning of Param i
15. ncSetDnetAttribute because both of these functions wait for the explicit message response internally National Instruments Corporation 2 29 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncCreateNotitication Create Notification DesiredState Continued Continued Description Established for the Explicit Messaging Object For the Explicit Messaging Object the Established state is clear not established before you start communication using ncOperateDnetIntf After you start communication the Established state remains clear until the explicit message connection has been successfully established with the remote DeviceNet device After the explicit message connection has been established the Established state sets and remains set for as long as the explicit message connection is open Until the Established state is set for the Explicit Messaging Object all calls to ncGetDnetAttribute ncSetDnetAttribute or ncWriteDnetExp1Msg return the error CanErrNot Started Before you call any of these functions in your application you must first wait for the Established state to set After the Established state is set unless communication problems occur with the device CanErrFunctionTimeout it remains set until you stop communication using ncOperateDnetIntf While waiting for one of the above states if an error occurs such as a communication error or an initialization error
16. 2 80 ncStatusToString 2 83 ncWaitForState 2 86 nceWriteDnetExpIMsg 2 91 nceWriteDnetIO 2 95 objects 3 1 Explicit Messaging Object 3 2 TVO Object 3 9 Interface Object 3 6 ni com 0 objects 3 1 Explicit Messaging Object 3 2 T O Object 3 9 Interface Object 3 6 P programming examples NI resources A 1 R related documentation viii National Instruments Corporation Index S software NI resources A 1 support technical A 1 T technical support A 1 training and certification NI resources A 1 troubleshooting NI resources A 1 W Web resources A 1 NI DNET Programmer Reference Manual
17. 3 NI DNET Objects 1 0 Object Inhibit Timer Attribute ID NC_ATTR_EXP_INHIBIT_TIMER Hex Encoding 80000097 Data Type NCTYPE_DURATION Permissions Set Description This driver attribute applies only to COS I O connections ncOpenDnetIO with ConnectionType of COS This driver attribute configures the minimum delay time between subsequent data productions This attribute can limit the amount of network traffic used for COS messages from devices with frequently changing I O The default value for Inhibit Timer is zero as specified in the DeviceNet Specification Since this default is appropriate for most applications the Inhibit Timer attribute is not included in the configuration attributes provided with ncOpenDnet I0 If you want to change the default Inhibit Timer call ncSetDriverAttr prior to starting communication If ConnectionType is Poll Strobe or Cyclic the Inhibit Timer attribute is ignored For these I O connection types the frequency of data production is controlled entirely by the ExpPacketRate attribute Input Length Attribute ID NC_ATTR_IN_LEN Hex Encoding 80000091 Data Type NCTYPE_UINT32 Permissions Get Description This driver attribute allows you to get the InputLength originally passed into ncOpenDnet Io NI DNET Programmer Reference Manual 3 12 ni com Chapter 3 NI DNET Objects 1 0 Object Keep Explicit Messaging
18. DNET Programmer Reference Manual Chapter 3 NI DNET Objects Interface Object Mac Id Attribute ID NC_ATTR_MAC_ID Hex Encoding 80000080 Data Type NCTYPE_UINT8 Permissions Get Description This driver attribute allows you to get the Int MacId originally passed into ncOpenDnetIntf Poll Mode Attribute ID NC_ATTR_POLL_MODE Hex Encoding 8000009B Data Type NCTYPE_POLL_MODE Permissions Get Description This driver attribute allows you to get the Po1 1Mode originally passed into ncOpenDnetIntf NI DNET Programmer Reference Manual 3 8 ni com Chapter 3 NI DNET Objects 1 0 Object 1 0 Object Description The I O Object represents an I O connection to a remote DeviceNet device physical device attached to your interface by a DeviceNet cable The I O Object usually represents T O communication as a master with a remote slave device If your computer is being used as the primary controller of your DeviceNet devices you should configure I O communication as a master You can also configure the I O Object for I O communication as a slave with a remote master If your computer is being used as a peripheral device for another primary controller you can configure I O communication as a slave To configure I O communication as a slave set the T O Object s DeviceMacId to the same MAC ID as the Interface Object Int fMacId parameter of ncOpenDnetIntf The I O Object supp
19. Manual Chapter 2 NI DNET Functions List of NI DNET Functions Examples Each function description includes sample LabVIEW and C code showing how to use the function For more detailed examples refer to the NI DNET User Manual for information regarding the location of example programs for LabVIEW and C List of NI DNET Functions Table 2 1 contains an alphabetical list of the NI DNET functions Table 2 1 NI DNET Functions Function Purpose EasylOClose Easy IO Close Close multiple NI DNET objects LabVIEW only Configure and open multiple NI DNET objects LabVIEW only EasylOConfig Easy IO Config ncCloseObject Close Close an NI DNET object ncConvertForDnetWrite Convert for DeviceNet Write Convert an appropriate LabVIEW data type for writing data bytes on the DeviceNet network Convert data from the DeviceNet network into an appropriate LabVIEW data type ncConvertFromDnetRead Convert From DeviceNet Read ncCreateNotification Create a notification callback for an object C only Create Notification Get an attribute value from a DeviceNet device using an Explicit Messaging Object ncGetDnetAttribute Get DeviceNet Attribute ncGetDriverAttr Get the value of an attribute in the NI DNET driver Get Driver Attribute Configure and open an NI DNET Explicit Messaging Object ncOpenDnetExp1Msg Open DeviceNet Explicit Messaging ncOpenDnetIntf Config
20. NCTYPE_UINTS should be used NCTYPE_STATUS status NCTYPE_OBJH objh NCTYPE_UINT8 mac_id NCTYPE_UINT16 device_error mac_id 12 status ncSetDnetAttribute objh 0x03 0x01 0x01 100 1 amp mac_id amp device_error National Instruments Corporation 2 79 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncSetDriverAttr Set Driver Attribute ncSetDriverAttr Set Driver Attribute Purpose Set the value of an attribute in the NI DNET driver Format LabVIEW ObjHandle in ObjHandle out AttrlD E t ttralue e Error in C NCTYPE_STATUS ncSetDriverAttr NCTYPE_OBJH ObjHandle NCTYPE_ATTRID AttrId NCTYPE_UINT32 SizeofAttr NCTYPE_ANY_P Attr Input ObjHandle Object handle of an open Explicit Messaging Object T O Object or Interface Object Attrid Identifier of the attribute to set SizeofAttr Size of the Attr buffer in bytes C only Attr New attribute value Output None Function Description ncSetDriverAttr sets the value of an attribute in the NI DNET driver software NI DNET objects use attributes to represent configuration settings status and other information Since you only need to access NI DNET driver attributes under special circumstances you seldom need to use ncSetDriverAttr For information about the attributes of each NI DNET object refer to Chapter 3 NI DNET Objects NI DNET Programmer Reference Manual 2 80 ni com Chapter 2 NI DNET Functions ncSetDr
21. Product Code Attribute ID NC_ATTR_PRODUCT_CODE Hex Encoding 80000083 Data Type NCTYPE_UINT16 Permissions Set Description Product Code of the device as reported in the Product Code attribute of device s Identity Object This attribute is used to verify that the device is the same one expected by your application If the Product Code does not match NI DNET returns the error DnetErrDeviInitProdCode The Product Code is a vendor specific value which identifies a particular product within a device type If you do not call ncSetDriveraAttr to set the Product Code a default value of zero is used When Product Code is zero NI DNET does not verify the device s Product Code Vendor Id Attribute ID NC_ATTR_VENDOR_ID Hex Encoding 80000082 Data Type NCTYPE_UINT16 Permissions Set Description Vendor ID of the device as reported in the Vendor ID attribute of device s Identity Object This attribute verifies that the device is the same one expected by your application If the Vendor ID does not match NI DNET returns the error DnetErrDevInitVendor The Vendor ID is a number assigned to the device vendor by the Open Device Vendor s Association ODVA If you do not call ncSetDriverAttr to set the Vendor ID a default value of zero is used When Vendor ID is zero NI DNET does not verify the device s Vendor ID ni com Technical Support and Professional Services Visit the following sections of the National Instru
22. Purpose Perform an operation on an NI DNET Interface Object Format LabVIEW ObjHandle in ObjHandie out Opcode E Param rror out Error in C NCTYPE_STATUS ncOperateDnetIntf NCTYPE_OBJH ObjHandle NCTYPE_UINT32 Opcode NCTYPE_UINT32 Param Input ObjHandle Object handle of an open Interface Object Opcode Operation code indicating which operation to perform Param Parameter whose meaning is defined by Opcode Output None Function Description ncOperateDnetIntf operates on an NI DNET Interface Object Use ncOperateDnet Intf to start and stop all DeviceNet communication for the associated interface including all explicit messaging and I O connections After you open the Explicit Messaging Objects and I O Objects required by your application you must use ncOperateDnetIntf to start communication You must also use ncOperateDnetIntf to stop communication before terminating your application NI DNET Programmer Reference Manual 2 64 ni com Chapter 2 NI DNET Functions ncOperateDnetintf Operate DeviceNet Interface Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from the ncOpenDnet Int f function In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the Interface Object Values The encoding of ObjHandle is internal to NI DNET Opcode Description Determines which operation to perform on the Interface Object
23. Specification allows 16 bit instance IDs most instance IDs are 8 bit NI DNET automatically uses the instance ID size 16 bit or 8 bit that is appropriate for your device Values 00 to FFFF hex Attributeld Description Identifies the attribute to set The class and instance descriptions list attribute IDs The attribute s description also lists the DeviceNet data type for the attribute s value Values 00 to FF hex Timeout Description Maximum time to wait for response from device To set the attribute in the device an explicit message request for the Set Attribute Single service is sent to the device After sending the service request this function must wait for the explicit message response for Set Attribute Single Timeout specifies the maximum number of milliseconds to wait for the response before giving up If the timeout expires before the response is received this function returns a status of BFF62001 hex CanErrFunctionTimeout For most DeviceNet devices a Timeout of 100 ms is appropriate The special timeout value of FFFFFFFF hex is used to wait indefinitely Values 1 to 1000 or FFFFFFFF hex infinite duration constant NC_DURATION_INFINIT OI xw AttrDataLength Description Number of attribute data bytes to set This length also specifies the number of bytes provided in AttrData Values 0 to 239 National Ins
24. as an ASCII string with format DNETx where x is a decimal number starting at zero that indicates which DeviceNet interface is being used You associate DeviceNet interface names with physical ports using Measurement amp Automation Explorer MAX Values DNETO DNET1 DNET31 In LabVIEW the interface name is selected from an enumerated list The LabWindows CVI function panel also provides an enumerated list IntfMacid Description MAC ID device address of the DeviceNet interface This is the MAC ID used by your DeviceNet interface for communication with other DeviceNet devices A device s MAC ID indicates the priority of its DeviceNet messages on the network with lower numbered MAC IDs having higher priority If your DeviceNet interface is the only master in the network the usual case this MAC ID is often set to 0 Values 0 to 63 National Instruments Corporation 2 49 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetintf Open DeviceNet Interface BaudRate Description Baud rate used for communication on the network connected to the DeviceNet interface The DeviceNet protocol supports baud rates of 125 000 250 000 and 500 000 b s Values 125000 250000 or 500000 In LabVIEW you select the baud rate from an enumerated list The LabWindows CVI function panel also provides an enumerated list PollMode Descriptio
25. for the object Values The encoding of ObjHandle is internal to NI DNET SizeofData Description For C SizeofData is the size of the buffer referenced by Data Use it to verify that you have enough bytes available to store the input bytes This size is normally obtained using the C language sizeof function and has no direct relation to the number of bytes received on the network For LabVIEW since the buffer for Data is allocated automatically by NI DNET this size is not needed The actual number of bytes received on the I O connection is determined by the InputLength parameter of ncOpenDnetIoO and not this size Values sizeof buffer referenced by Data Data Description Input data The format of these input bytes is specific to your DeviceNet device Values Input data bytes National Instruments Corporation 2 73 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncReadDnetlO Read DeviceNet 1 0 Examples LabVIEW Read 20 input bytes from an I O Object ObjiHandie in ObsHandile out Error in Error out C Read 10 input bytes from the I O Object referenced by objh NCTYPE_STATUS status NCTYPE_OBJH objh NCTYPE_UINTS8 input 10 status ncReadDnetIO objh 10 input NI DNET Programmer Reference Manual 2 74 ni com Chapter 2 NI DNET Functions ncSetDnetAttribute Set DeviceNet Attribute ncSetDnetAttribute Set DeviceNet Attribute P
26. instance ID 1 attribute ID 2 and its DeviceNet data type is UINT Use ncConvertFromDnetRead to convert the Device Type into an appropriate LabVIEW data type DeviceError ObjHandie in ObsHandie out Error in ButeOffset 10 Convert From DeviceNet Read vi National Instruments Corporation 2 25 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncConvertFromDnetRead Convert From DeviceNet Read C 1 Demonstrate the same conversions as LabVIEW example 1 NCTYPE_UINTS8 data 8 NCTYPE_INT32 ActualPos DINT NCTYPE_BOOL CurrentDir BOOL NCTYPE_BOOL TrajiInProg BOOL status ncReadDnetIO objh sizeof data data Take the address of the data byte at offset 4 cast that address to point to the appropriate C language data type then dereference the pointer ActualPos NCTYPE_INT32 amp data 4 If bit 4 of byte 0 is set then CurrentDir is true If bit 0 of byte 0 is set the TrajInProg is true CurrentDir data 0 amp 0x10 NC_TRUE NC_FALSE TrajInProg data 0 amp 0x01 NC_TRUE NC_FALSE 2 Demonstrate the same conversion as LabVIEW example 2 NCTYPE_UINT16 device_type NCTYPE_UINT16 actual_length Conversion is performed automatically simply by passing in a pointer to the appropriate C language data type status ncGetDnetAttribute objh 0x01 0x01 0x02 100 sizeof device type amp device_type amp actual_l
27. it no longer needs to be in use such as when the application is about to terminate When an object is closed NI DNET stops all pending operations for the object and you can no longer use the Obj Hand1e in your application If the object specified by ObjHand1e has a notification pending ncCloseObject disables the notification by implicitly calling ncCreateNotification with DesiredState zero When ncCloseObject has been called for all open NI DNET objects NI DNET stops all DeviceNet communication ncCloseObject issues an implicit call to ncOperateDnetIntf with Opcode NC_OP_STOP NI DNET Programmer Reference Manual 2 10 ni com Chapter 2 NI DNET Functions ncCloseObject Close Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from the ncOpenDnetIntf ncOpenDnetExp1Msg or ncOpenDnet IO function Values The encoding of Obj Hand1e is internal to NI DNET Examples LabVIEW Close an NI DNET object ObsHandie in ne ES Error in Close an NI DNET object NCTYPE_STATUS status NCTYPE_OBJH objh status ncCloseObject objh National Instruments Corporation 2 11 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncConvertForDnetWrite Convert For DeviceNet Write ncConvertForDnetWrite Convert For DeviceNet Write Purpose Convert an appropriate LabVIEW data type for writing data bytes on the DeviceNet network Form
28. object handle returned from ncOpenDnetExp1Msg ncOpenDnetIntf or ncOpenDnetIO In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the object Values The encoding of ObjHandle is internal to NI DNET Attrid Description Identifier of the NI DNET attribute Supported attribute identifiers for each NI DNET object are listed in Chapter 3 NI DNET Objects Values 80000000 to 8000FFFF hex high bit differentiates from DeviceNet IDs SizeofAttr Description For C this is the size of the buffer referenced by At tr It is used to verify that you have enough bytes available to store the attribute s value This size is normally obtained using the C language sizeof function For LabVIEW since the buffer for At tr is allocated automatically by NI DNET this size is not needed Values sizeof buffer referenced by Attr Attr Description Returned attribute value The value is usually returned in an unsigned 32 bit integer and thus At tr is of type NCTYPE_UINT32_P Values Value of NI DNET attribute National Instruments Corporation 2 43 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncGetDriverAttr Get Driver Attribute Examples LabVIEW Get the DeviceNet protocol version supported by NI DNET ObjiHandie in ObsHandie out 1ntf Protocol Version tti alue Error in Error out Get the version of the NI DNET software using the Interface Obj
29. single bit represents each state For example if NI DNET provides states with values of hex 1 and hex 4 DesiredState of hex 5 enables notification for both states ReadAvail for the I O Object ReadAvail for the Explicit Messaging Object For the I O Object the ReadAvail state sets when a new input message is received from the network The ReadAvail state clears when you call ncReadDnetI0 For example for a change of state COS I O connection the notification occurs when a COS input message is received The typical behavior for your callback function is to call ncReadDnet1I0 to read the new input data perform any calculations needed call ncWriteDnetIo to provide output data then return from the callback function For the Explicit Messaging Object the ReadAvail state sets when an explicit message response is received from the network The ReadAvail state clears when you call ncReadDnetExp1Msg An explicit message response is received only after you send an explicit message request using ncWriteDnetExp1Msg Although using a notification for an explicit message response allows for execution of other code while waiting it is often more straightforward to use the following sequence of calls ncWriteDnetExp1Msg ncWaitForState ncReadDnetExp1Msg This is the sequence used internally by ncGetDnetAttribute and ncSetDnetAttribute The ReadAvail state is not needed when using the explicit messaging functions ncGetDnetAttribute and
30. the desired states occurs it provides the current value of the ReadAvail and Established states If the Timeout expires before one of the desired states occurs it has the value 0 Status Current status of the object If one of the desired states occurs it has the value 0 DnetSuccess If the Timeout expires before one of the desired states occurs it has the value BFF62001 hex CanErrFunctionTimeout RefData Pointer to your reference data as originally passed to ncCreateNotification NI DNET Programmer Reference Manual 2 32 ni com Chapter 2 NI DNET Functions ncCreateNotitication Create Notification Callback Continued Description Continued Return Value from Callback The value you return from the callback indicates the desired states to re enable for notification If you want to continue to receive notifications return the same value as the original DesiredState parameter If you no longer want to receive notifications return a value of 0 If you return a nonzero value from the callback and one of those states is still set the callback is invoked again immediately after you return For example if you return ReadAvail from the callback without calling ncReadDnetIo to read the available data the callback is invoked again Information Specific to LabWindows CVI When the NI DNET device driver calls your notification callback it does so in a separate thread within the LabWindows CVI p
31. variable of the appropriate data type as specified in Chapter 1 NI DNET Data Types Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from the ncOpenDnetExp1Msg function In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the object Values The encoding of ObjHandle is internal to NI DNET Classid Description Identifies the class which contains the attribute For descriptions and identifiers for each standard DeviceNet class refer to the DeviceNet Specification Volume 2 Chapter 6 The DeviceNet Object Library Vendor specific classes are documented by the device vendor Although the DeviceNet Specification allows 16 bit class IDs most class IDs are 8 bit NI DNET automatically uses the class ID size 16 bit or 8 bit that is appropriate for your device Values 00 to FFFF hex National Instruments Corporation 2 37 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncGetDnetAttribute Get DeviceNet Attribute Instanceld Description Identifies the instance which contains the attribute Instance ID 0 is used to get an attribute from the class itself Other instance IDs typically are numbered starting at 1 For example the primary Identity Object in a device uses instance ID 1 Although the DeviceNet Specification allows 16 bit instance IDs most instance IDs are 8 bit NI DNET
32. A LEVEL OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT INJURY TO A HUMAN 2 IN ANY APPLICATION INCLUDING THE ABOVE RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE IMPAIRED BY ADVERSE FACTORS INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY COMPUTER HARDWARE MALFUNCTIONS COMPUTER OPERATING SYSTEM SOFTWARE FITNESS FITNESS OF COMPILERS AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION INSTALLATION ERRORS SOFTWARE AND HARDWARE COMPATIBILITY PROBLEMS MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL DEVICES TRANSIENT FAILURES OF ELECTRONIC SYSTEMS HARDWARE AND OR SOFTWARE UNANTICIPATED USES OR MISUSES OR ERRORS ON THE PART 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 INSTRU
33. Basic each NI DNET function returns a status code as a signed 32 bit integer Table 2 2 summarizes the NI DNET use of this status Table 2 2 NI DNET Status Codes Status Code Meaning Negative Error Function did not perform expected behavior Positive Warning Function performed as expected but a condition arose that may require your attention Zero Success Function completed successfully National Instruments Corporation 2 83 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncStatusToString Status To String ncStatusToString converts a status value returned from an NI DNET function into a descriptive string By displaying this string when an error or warning is detected you can avoid interpretation of the numeric code to debug the problem The ncStatustoString function is not applicable to LabVIEW programming For LabVIEW NI DNET functions use the standard error in and error out clusters for status information You can view error descriptions using built in LabVIEW features such as Explain Error in the Help menu or the Simple Error Handler VI in your diagram If you want to avoid displaying error messages while debugging your application you can use the Explain exe utility This console application is in the Utilities subfolder of the NI DNET installation folder which is typically Program Files National Instruments NI DNET Utilities You enter an NI DNET status code in th
34. Configuration Cluster F Error out Error in C NCTYPE_STATUS Input Int fName IntfMacId BaudRate PollMode Output ObjHandle Function Description ncOpenDnetIntf NCTYPE_STRING IntfName NCTYPE_UINT32 IntfMacId NCTYPE_UINT32 BaudRate NCTYPE_UINT32 PollMode NCTYPE_OBJH_P ObjHandle Name of DeviceNet interface MAC ID of the DeviceNet interface Baud rate Communication scheme for all polled I O connections Object handle you use with all subsequent function calls for the Interface Object ncOpenDnetIntf configures and opens an NI DNET Interface Object and returns a handle that you use with all subsequent function calls for that object The Interface Object represents a DeviceNet interface Since this interface acts as a device on the DeviceNet network much like any other device it is configured with its own MAC ID and baud rate NI DNET Programmer Reference Manual 2 48 ni com Chapter 2 NI DNET Functions ncOpenDnetintf Open DeviceNet Interface Use the Interface Object to do the following e Configure NI DNET settings which apply to the entire interface e Start and stop communication for all NI DNET objects associated with the interface The Interface Object must be the first NI DNET object opened by your application and thus ncOpenDnetInt must be the first NI DNET function called by your application Parameter Descriptions IntfName Description Name of the DeviceNet interface
35. DeviceNet NI DNET Programmer Reference Manual April 2006 7 NATIONAL 370376C 01 N INSTRUMENTS 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 0 662 45 79 90 0 Belgium 32 0 2 757 00 20 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 9 725 725 11 France 33 0 1 48 14 24 24 Germany 49 0 89 741 31 30 India 91 80 41190000 Israel 972 0 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 7 095 783 68 51 Singapore 1800 226 5886 Slovenia 386 3 425 4200 South Africa 27 0 11 805 8197 Spain 34 91 640 0085 Sweden 46 0 8 587 895 00 Switzerland 41 56 200 51 51 Taiwan 886 02 2377 2222 Thailand 662 278 6777 United Kingdom 44 0 1635 523545 For further support information refer to the Technical Support and Professional Services appendix To comment on National Instruments documentation refer to the National Instruments Web site at ni com info and enter the info code feedback 2001 2006 National Instruments Corporation All rights rese
36. ET Functions ncWriteDnetExplMsg Write DeviceNet Explicit Message Description Identifies the class to which service is directed You can find descriptions and identifiers for each standard DeviceNet class in the DeviceNet Specification Volume 2 Chapter 6 The DeviceNet Object Library The device s vendor documents vendor specific classes Although the DeviceNet Specification allows 16 bit class IDs most class IDs are 8 bit NI DNET automatically uses the class ID size 16 bit or 8 bit that is appropriate for your device Values 00 to FFFF hex Instanceld Description Identifies the instance to which service is directed Instance ID 0 is used to direct the service toward the class itself Other instance IDs typically are numbered starting at 1 For example the primary Identity Object in a device uses instance ID 1 Although the DeviceNet Specification allows 16 bit instance IDs most instance IDs are 8 bit NI DNET automatically uses the instance ID size 16 bit or 8 bit that is appropriate for your device Values 00 to FFFF hex ServDataLengt Description Number of service data bytes for the request This length also specifies the number of bytes provided in ServData Values 0 to 240 ServData Description Service data bytes for the request The format of this data is specific to the service code being used For commonly used services which are not object specifi
37. MENTS TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE INCORPORATED IN A SYSTEM OR APPLICATION INCLUDING WITHOUT LIMITATION THE APPROPRIATE DESIGN PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION Contents About This Manual How to Use the Manual Set 0 0 0 0 cccccccceccssssssscscsscesesecccccececessesesessssssnsssressessseseeeeess Vii CONVENTIONS ss rs et a cdeea nn mi A era Mt ls tn sons Vili Related Documentation tin Rs RE dns ein taste viii Chapter 1 NI DNET Data Types Chapter 2 NI DNET Functions Using the Function Descriptions ss 2 1 List Of NEDNET FUNCHONS enn sistema tee tester 2 2 EasyIOCIose Easy T0 Close nes mt sn et gen tite ie 2 4 EasylOConfig Easy IO Config sisi 2 6 nCCloseObject Close is s E italie oA iaia 2 10 ncConvertForDnetWrite Convert For DeviceNet Write 2 12 ncConvertFromDnetRead Convert From DeviceNet Read 2 20 ncCreateNotification Create Notification ss 2 27 ncGetDnetAttribute Get DeviceNet Attribute ss 2 36 ncGetDriverAttr Get Driver Attribute sssssssss 2 42 ncOpenDnetExplMsg Open D
38. Msg ncWaitForState ncReadDnetExp1Msg The ncWriteDnetExp1Msg function sends an explicit message request to a remote DeviceNet device The ncWaitForState function waits for the explicit message response and the ncReadDnetExp1Msg function reads that response Some DeviceNet services that use ncWriteDnetExp1Msg are Reset Save Restore Get Attributes All and Set Attributes All Although the DeviceNet Specification defines the overall format of these services in most cases their meaning and service data are object specific or vendor specific Unless your device requires such services and documents them in detail you probably do not need them for your application For more information refer to the NI DNET User Manual Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from ncOpenDnetExp1Msg In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the object Values The encoding of ObjHand1e is internal to NI DNET ServiceCode Description Identifies the service being requested You can find service code values for the commonly used DeviceNet services in the DeviceNet Specification Volume 1 Appendix G DeviceNet Explicit Messaging Services The device s vendor documents vendor specific service codes Values 00 to FF hex NI DNET Programmer Reference Manual 2 92 ni com Chapter 2 Classid NI DN
39. NET Programmer Reference Manual Chapter 2 NI DNET Functions ncWriteDnetlO Write DeviceNet 1 0 The bytes of a device s output assembly often consist of multiple data members rather than a single value For C you can often place each data member into the output bytes by using typecasting For LabVIEW you can often place each data member into the output bytes using the ncConvertForDnetWrite function For more information on output assemblies and how to place individual data members into the output bytes refer to the NJ DNET User Manual Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from ncOpenDnet 10 In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the object Values The encoding of ObjHand1e is internal to NI DNET SizeofData Description For C SizeofData is the size of the buffer referenced by Data It is used to verify that the Data buffer is large enough to hold the output bytes This size is normally obtained using the C language sizeof function and has no direct relation to the number of bytes produced on the network For LabVIEW since Data is obtained directly as an input this size is not needed The actual number of bytes produced on the I O connection is determined by the OutputLength parameter of ncOpenDnetI0 and not this size Values sizeof buffer referenced by Data Data Descript
40. PacketRate of that connection s I O Object Use individual polling when you have detailed knowledge of the time it takes each device to perform its physical measurement or control function For example if you have a discrete input device capable of acquiring a new measurement every 10 ms an analog input device with a measurement rate of 45 ms and a temperature sensor with a measurement rate of 200 ms you could use individual polling to communicate with each device at its exact measurement rate Since communication occurs only at the actual rate needed for each device individual polling often provides optimum network usage For additional information on Pol1Mode and ExpPacketRate refer to the NI DNET User Manual Values Automatic constant NC_POLL_AUTO value 0 Scanned constant NC_POLL_SCAN value 1 Individual constant NC_POLL_INDTIV value 2 In LabVIEW you select the poll mode from an enumerated list The LabWindows CVI function panel also provides an enumerated list ObjHandle Description If the ncOpenDnet Int f function is successful a handle to the newly opened Interface Object is returned in ObjHandle This handle is used with all subsequent function calls for that Interface Object The function most commonly used with the Interface Object is ncOperateDnetIntf Values The encoding of ObjHand1e is internal to NI DNET NI DNET Programmer Reference Manual 2 52 ni com
41. ServiceCode DeviceNet service code from response ServData Service data from response ActualServDataLength Actual number of service data bytes in response Function Description ncReadDnetExp1Msg reads an explicit message response from an Explicit Messaging Object The two most commonly used DeviceNet explicit messages are the Get Attribute Single service and the Set Attribute Single service The easiest way to execute the Get Attribute Single service on a remote device is to use the NI DNET ncGetDnetAttribute function NI DNET Programmer Reference Manual 2 68 ni com Chapter 2 NI DNET Functions ncReadDnetExpiMsg Read DeviceNet Explicit Message The easiest way to execute the Set Attribute Single service on a remote device is to use the NI DNET ncSetDnetAttribute function To execute services other than Get Attribute Single and Set Attribute Single use the following sequence of function calls ncwriteDnetExp1Msg ncWaitForState ncReadDnetExp1Msg The ncWriteDnetExp1Msg function sends an explicit message request to a remote DeviceNet device The ncWaitForState function waits for the explicit message response and the ncReadDnetExp1Msg function reads that response Some of the DeviceNet services which use ncReadDnetExp1Msg are Reset Save Restore Get Attributes All and Set Attributes All Although the DeviceNet Specification defines the overall format of these services in most cases their meaning and service data
42. T object Refer to ncOpenDnetExplMsg ncOpenDnetInt f and ncOpenDnetIoO in Chapter 2 NI DNET Functions NCTYPE_VERSION unsigned long U32 N A Version number Major minor subminor and beta version numbers are encoded in unsigned 32 bit integer from high byte to low byte Letters are encoded as numeric equivalents A is 1 Z is 26 and so on Version 2 0B would be hexadecimal 02000200 and Beta version 1 4 2 beta 7 would be hex 01040207 NCTYPE_DURATION unsigned long U32 N A Time duration indicating elapsed time between two events Time is expressed in 1 ms increments For example 10 s is 10 000 Special constant NC_DURATION_NONE 0 is used for zero duration and NC_DURATION_ INFINITE FFFFFFFF hex is used for infinite duration NCTYPE_ATTRID unsigned long U32 N A Identifier used to access internal attributes in the NI DNET device driver not attributes in DeviceNet devices Refer to Chapter 3 NI DNET Objects NI DNET Programmer Reference Manual ni com Chapter 1 NI DNET Data Types Table 1 1 NI DNET Data Types Continued NI DNET Data Type ANSI C LabVIEW DeviceNet Description NCTYPE_OPCODE unsigned long U32 N A Operation code used with ncOperateDnetIntf function NCTYPE_STATE unsigned long U32 N A Object states encoded as 32 bit mask one bit for each state For information refer toncWaitForStatein Chapt
43. U8 in Description If the selected Dnet Type is USINT UINT or UDINT this input terminal provides the LabVIEW data to convert into a DeviceNet data member Although the LabVIEW data type for this input terminal is U32 it can be coerced automatically from U16 or U8 Values LabVIEW data to convert into a DeviceNet data member DBL SGL in Description If the selected Dnet Type is REAL or LREAL this input terminal provides the LabVIEW data to convert into a DeviceNet data member Although the LabVIEW data type for this input terminal is DBL it can be coerced automatically from SGL Values LabVIEW data to convert into a DeviceNet data member abe in Description If the selected Dnet Type is SHORT_STRING or STRING this input terminal provides the LabVIEW data to convert into a DeviceNet data member The LabVIEW data type for this input terminal is abc Values LabVIEW data to convert into a DeviceNet data member DnetData out Description DeviceNet data bytes with member inserted These data bytes are written on the DeviceNet network using the ncWriteDnetIo ncSetDnetAttribute or ncWriteDnetExplMsg function If you need to convert multiple DeviceNet data members you can also wire this output terminal into the DnetData in input terminal of a subsequent use of this function Values Data input terminal of ncWriteDnetIO or AttrData input terminal of ncSetDnetAttribute or ServData input terminal o
44. UINTS8 I NCTYPE_INT32 TargetPos DINT NCTYPE_BOOL Enable BOOL NCTYPE_BOOL StartTraj BOOL Initialize default values of zero for I 0 I lt 8 I data I 0 If Enable is true set bit 7 of byte 0 If StartTraj is true set bit 0 of byte 0 if Enable NC_TRUE data 0 0x80 if StartTraj NC TRUE data 0 0x01 Take the address of the data byte at offset 4 cast that address to point to the appropriate C language data type then dereference the pointer in order to store the value NI DNET Programmer Reference Manual 2 18 ni com Chapter 2 NI DNET Functions ncConvertForDnetWrite Convert For DeviceNet Write NCTYPE_INT32 amp data 4 TargetPos status ncWriteDnetIO objh sizeof data data 2 Demonstrate the same conversion as LabVIEW example 2 NCTYPE_LREAL foo Conversion is performed automatically simply by passing in a pointer to the appropriate C language data type foo 354654 4543 status ncSetDnetAttribute objh 0xD5 0x01 0x05 100 sizeof foo amp foo National Instruments Corporation 2 19 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncConvertFromDnetRead Convert From DeviceNet Read ncConvertFromDnetRead Convert From DeviceNet Read Purpose Convert data read from the DeviceNet network into an appropriate LabVIEW data type Format LabVIEW ABC O
45. VIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the object Values The encoding of ObjHandle is internal to NI DNET DesiredState Description States to wait for Each state is represented by a single bit so that you can wait for multiple states simultaneously For example if NI DNET provides states with values of hex 1 and hex 4 DesiredState of hex 5 waits for either state to occur ReadAvail for the I O Object For the I O Object the ReadAvail state is set when a new input message is received from the network The ReadAvail state clears when you call ncReadDnet I0 For example for a change of state COS I O connection the ReadAvail state sets when a COS input message is received Although you can use ncWaitForState with an I O Object it is often preferable to use a notification ncCreateNotification C only Use of a notification callback for the ReadAvail state allows your application to handle multiple I O connections independently National Instruments Corporation 2 87 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncWaitForState Wait For State DesiredState Continued Continued Description ReadAvail for the Explicit Messaging Object Established for the Explicit Messaging Object For the Explicit Messaging Object the ReadAvail state sets when an explicit message response is received from th
46. _UINT8 type_of_reset type_of_reset 0 status ncWriteDnetExplMsg objh 0x05 0x01 0x01 1 amp type_of_reset NI DNET Programmer Reference Manual 2 94 ni com Chapter 2 NI DNET Functions ncWriteDnetlO Write DeviceNet 1 0 neWriteDnetlO Write DeviceNet 1 0 Purpose Write output data to an I O Object Format LabVIEW ObjHandle in ObjHandle out Data Error in Error out C NCTYPE_STATUS ncWriteDnetIO NCTYPE_OBJH ObjHandle NCTYPE_UINT32 SizeofData NCTYPE_ANY_P Data Input ObjHandle Object handle of an open I O Object SizeofData Size of Data buffer in bytes C only Data Output data Output None Function Description ncWriteDnetIO writes output data to an NI DNET I O Object Since each I O Object continuously produces output data onto the DeviceNet network at a specified rate calling ncWriteDnetIO multiple times for each output message is redundant and can often waste valuable processor time To synchronize calls to ncWriteDnetIo with each output message you can wait for input data see ncReadDnet 10 or if no input data exists for the device you can use an idle wait such as wait for 10 ms The output data bytes passed to ncWriteDnetIo are normally sent to the output assembly of a remote DeviceNet slave device The format of this output assembly is normally documented either by the device vendor or within the DeviceNet Specification itself National Instruments Corporation 2 95 NI D
47. a member Although the LabVIEW data type for this output terminal is U32 it can be coerced automatically to U16 or U8 Values Converted DeviceNet data member DBL SGL out Description If the selected Dnet Type is REAL or LREAL this output terminal provides the converted DeviceNet data member Although the LabVIEW data type for this output terminal is DBL it can be coerced automatically to SGL Values Converted DeviceNet data member abe out Description If the selected Dnet Type is SHORT_STRING or STRING this output terminal provides the converted DeviceNet data member The LabVIEW data type for this output terminal is abc Values Converted DeviceNet data member Examples LabVIEW 1 Use ncReadDnetI0 to read Response Assembly 1 from a Position Controller In this input assembly the byte at offset 0 consists of 8 BOOL and the bytes at offset 4 7 consist of an Actual Position of type DINT Use ncConvertFromDnetRead to convert these DeviceNet data members into appropriate LabVIEW data types NI DNET Programmer Reference Manual 2 24 ni com 2 Chapter 2 NI DNET Functions ncConvertFromDnetRead Convert From DeviceNet Read gt BOOL TF aro Disc error ObjHandie in Index Array Error in Erroront Read DeviceNet 10 _vi DINT 132 ByteOifset Convert From DeviceNet Read vi Get the Device Type attribute using the ncGetDnetAttribute function The Device Type is contained in the Identity Object class ID 1
48. act your local office or NI corporate headquarters Phone numbers for our worldwide offices are listed at the front of this manual You also can visit the Worldwide Offices section of ni com niglobal to access the branch office Web sites which provide up to date contact information support phone numbers email addresses and current events National Instruments Corporation A 1 NI DNET Programmer Reference Manual Glossary Symbol Prefix Value m milli 10 3 k kilo 103 A ANSI American National Standards Institute Application A collection of functions used by a user application to access hardware Programming Within NI DNET you use API functions to make calls into the NI DNET Interface API ASCII attribute b bit strobed I O C CAN change of state I O class National Instruments Corporation G 1 driver American Standard Code for Information Interchange The externally visible qualities of an object for example an instance square of class geometric shapes could have the attributes length of sides and color with the values 4 in and blue Also known as property Bits Master slave I O connection in which the master broadcasts a single strobe command to all strobed slaves then receives a strobe response from each strobed salve Controller Area Network Master slave I O connection which is similar to cyclic I O but data can be sent when a change in the data is detected
49. ammer Reference Manual Chapter 2 NI DNET Functions ncCreateNotitication Create Notification You normally use ncCreateNotification when you want to let other code to execute while waiting for NI DNET states especially when the other code does not call NI DNET functions If you do not need such background execution ncWaitForState offers better overall performance You cannot use ncWaitForState at the same time as ncCreateNotification This function is not supported for Visual Basic 6 The Status parameter of your callback function indicates any error detected by NI DNET You should always check this Status parameter prior to checking the CurrentState parameter of your callback function When ncCreateNotification returns successfully NI DNET calls your notification callback function whenever one of the states specified by DesiredState occurs in the object If DesiredState is 0 NI DNET disables notifications for the object specified by ObjHandle Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from ncOpenDnetExp1Msg or ncOpenDnet 10 Values The encoding of ObjHand1e is internal to NI DNET NI DNET Programmer Reference Manual 2 28 ni com DesiredState Chapter 2 NI DNET Functions ncCreateNotitication Create Notification Description States for which notification is called So that notification can be enabled for multiple states simultaneously a
50. are object specific or vendor specific Unless your device requires such services and documents them in detail you probably do not need them for your application For more information refer to the NI DNET User Manual Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from ncOpenDnetExp1Msg In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the object Values The encoding of ObjHandle is internal to NI DNET National Instruments Corporation 2 69 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncReadDnetExplMsg Read DeviceNet Explicit Message ServiceCode Description Identifies the service response as either success or error If the response is success this value is the same as the ServiceCode of the request ncWriteDnetExplMsg and the ServData bytes are formatted as defined by the service If the response is error this value is 14 hex ServData 0 contains a General Error Code and ServData 1 contains an Additional Code Either the DeviceNet Specification or the object itself define the error codes Although the DeviceNet Specification requires the high bit of the service code hex 80 to be set in all explicit message responses NI DNET clears this response indicator so that you can compare the actual service code to the value used with ncWriteDnetExplMsg
51. at LabVIEW Byte Offset Dnet Type Dnet Data In U32 U16 U8 324116418 BOOLEAN DBL SGL ABC In Modified Dnet Data Out C Not applicable but see Examples at the end of this section Input DnetData in DnetType ByteOffset 8 TF in 132 116 I8 in U32 U16 U8 in DBL SGL in abc in Output DnetData out Function Description Initial data bytes to write on the DeviceNet network DeviceNet data type to convert into Byte offset of the DeviceNet member to convert into LabVIEW array of 8 TF to convert from LabVIEW 132 116 or I8 to convert from LabVIEW u32 U16 or U8 to convert from LabVIEW DBL or SGL to convert from LabVIEW string to convert from DeviceNet data bytes with member inserted Many fundamental differences exist between the encoding of a DeviceNet data type and its equivalent data type in LabVIEW For example for a 32 bit integer the DeviceNet DINT data type uses Intel byte ordering lowest byte first and the equivalent LabVIEW 132 data type uses Motorola byte ordering highest byte first NI DNET Programmer Reference Manual 2 12 ni com Chapter 2 NI DNET Functions ncConvertForDnetWrite Convert For DeviceNet Write ncConvertForDnetWrite takes an initial sequence of bytes to write on the DeviceNet network and given the byte offset and DeviceNet data type for a specific data member converts an appropriate LabVIEW data type for placement into those data bytes You provide initial data by
52. ation For more information refer to the description of the I O Object in Chapter 3 NI DNET Objects Values Poll constant NC_CONN_POLL value 0 Strobe constant NC_CONN_STROBE value 1 COS constant NC_CONN_COS value 2 Cyclic constant NC_CONN_CYCLIC value 3 In LabVIEW you select the connection type from an enumerated list The LabWindows CVI function panel also provides an enumerated list National Instruments Corporation 2 57 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetlO Open DeviceNet 1 0 InputLength Description Number of input bytes for the I O connection This is the number of bytes read from the I O connection using the ncReadDnet IO function The following information is specific to the ConnectionType setting Poll COS and Cyclic For these I O connection types the input length is the same as the number of bytes consumed from the remote device Strobe as master DeviceMacId not equal to Int fMacId For this I O connection the input length is the same as the number of bytes consumed from the strobe response message and must have a value from 0 to 8 Strobe as slave DeviceMacId equal to Int fMacId For this I O connection the input length must have a value of 1 The input data consists of a single Boolean value bit obtained from the master s strobe command message using Int f MacId This Boolean value is returned from the ncReadDnet IO functio
53. automatically uses the instance ID size 16 bit or 8 bit that is appropriate for your device Values 00 to FFFF hex Attributeld Description Identifies the attribute to get Attribute IDs are listed in the class and instance descriptions in the DeviceNet Specification The attribute s description also lists the DeviceNet data type for the attribute s value Values 00 to FF hex Timeout Description Maximum time to wait for response from device To get the attribute from the device an explicit message request for the Get Attribute Single service is sent to the device After sending the service request this function must wait for the explicit message response for Get Attribute Single Timeout specifies the maximum number of milliseconds to wait for the response before giving up If the timeout expires before the response is received this function returns a status of BFF62001 hex CanErrFunctionTimeout For most DeviceNet devices a Timeout of 100 ms is appropriate The special timeout value of FFFFFFFF hex is used to wait indefinitely Values 1 to 1000 or FFFFFFFF hex infinite duration constant NC_DURATION_INFINITE NI DNET Programmer Reference Manual 2 38 ni com SizeofAttrData Chapter 2 NI DNET Functions ncGetDnetAttribute Get DeviceNet Attribute Description For C this is the size of the buffer referenced by AttrData It is used to verify that you have en
54. bytes to write on the DeviceNet network or DnetData out output terminal of a previous use of this function National Instruments Corporation 2 13 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncConvertForDnetWrite Convert For DeviceNet Write DnetType Description An enumerated list from which you choose the DeviceNet data type to convert into For each DeviceNet data type the appropriate LabVIEW data type is listed in parentheses When you select the DeviceNet data type BOOL ncConvertForDnetWrite converts the byte indicated by ByteOffset from an array of eight LabVIEW Booleans You can index into this array to change specific Boolean members The Boolean at index zero is the least significant bit bit 0 the Boolean at index one is the next least significant bit 1 and so on Values BOOL 8 TF SINT I8 INT 116 DINT 132 USINT U8 UINT U16 UDINT U32 REAL SGL 1 R AL DBL SHORT_STRING abc STRING abc NI DNET Programmer Reference Manual 2 14 ni com ByteOffset Chapter 2 NI DNET Functions ncConvertForDnetWrite Convert For DeviceNet Write Description Byte offset of the DeviceNet member to convert into For the DeviceNet data member you want to replace this is the byte offset in DnetData in where the member begins Byte offsets start at zero You can find information on the format of your Devic
55. c the format of this data is defined in the DeviceNet Specification Volume 1 Appendix G DeviceNet Explicit Messaging Services For object specific service codes the format of this data is defined in the object specification For vendor specific service codes the format of this data is defined by the device vendor The ServDataLength parameter specifies the number of service data bytes sent in the request and provided in this buffer Values Service data bytes for the request National Instruments Corporation 2 93 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncWriteDnetExplMsg Write DeviceNet Explicit Message Examples LabVIEW Save the parameters of Parameter Object instance 2 to non volatile memory The service code for Save is 16 hex The Parameter Object is class ID OF hex The Parameter Object does not define any service data bytes for Save ObjiHandie in ObsHandie out ClassiD Instanceld Error out Error in ServDataLenath C Reset a DeviceNet device to its power on state using the Explicit Messaging Object referenced by objh The service code for Reset is 05 hex The Identity Object class ID 1 instance ID 1 is used to reset DeviceNet devices The Identity Object defines a single byte of service data where 0 is used to simulate a power cycle and 1 is used to reset the device to its out of box state NCTYPE_STATUS status NCTYPE_OBJH objh NCTYPE
56. cross reference or an introduction to a key 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 Italic text in this font denotes text that is a placeholder for a word or value that you must supply Related Documentation The following documents contain information that you might find helpful as you read this manual e CAN Specification Version 2 0 1991 Robert Bosch Gmbh Postfach 500 D 7000 Stuttgart 1 e DeviceNet Specification Volumes 1 and 2 Version 2 0 Open DeviceNet Vendor Association e LabVIEW online reference e Microsoft Win32 Software Development Kit SDK online help NI DNET Programmer Reference Manual viii www ni com NI DNET Data Types This chapter describes the data types used by NI DNET functions and objects The NI DNET data types provide consistency for various programming environments and facilitate access to the DeviceNet network In general all NI DNET data types begin with NCTYPE_ Table 1 1 lists each NI DNET data type its equivalent data type in ANSI C LabVIEW and DeviceNet and a brief description Tabl
57. does not ping the explicit messaging connection If you are certain that your application sends a request on a periodic basis you can set this attribute to NC_FALSE This attribute must be set prior to starting communication Mac Id Attribute ID NC_ATTR_MAC_ID Hex Encoding 80000080 Data Type NCTYPE_UINT8 Permissions Get Description This driver attribute allows you to get the DeviceMacId originally passed into ncOpenDnetExp1Msg NI DNET Programmer Reference Manual 3 4 ni com Chapter 3 NI DNET Objects Explicit Messaging Object Product Code Attribute ID NC_ATTR_PRODUCT_ CODE Hex Encoding 80000083 Data Type NCTYPE_UINT16 Permissions Set Description Product Code of the device as reported in the Product Code attribute of device s Identity Object This attribute verifies that the device is the same one expected by your application If the Product Code does not match NI DNET returns the error DnetErrDeviInit ProdCode The Product Code is a vendor specific value which identifies a particular product within a device type If you do not call ncSetDriveraAttr to set the Product Code a default value of zero is used When Product Code is zero NI DNET does not verify the device s Product Code Vendor Id Attribute ID NC_ATTR_VENDOR_ID Hex Encoding 80000082 Data Type NCTYPE_UINT16 Permissions Set Description Vendor ID of the device as reported in the V
58. e ServiceCode ClassId Instanceld ServDataLength ServData Output None National Instruments Corporation ServData ServiceCode ObjHandle in ClassID Instanceld Error in ServDataLength ObjHandle out Error out ncWriteDnetExplMsg NCTYPE_OBJH ObjHandle NCTYPE_UINT8 ServiceCode NCTYPE_UINT16 ClassId NCTYPE_UINT16 Instanceld NCTYPE_UINT16 ServDataLength NCTYPE_ANY_P ServData Object handle of an open Explicit Messaging Object Identifies the service being requested Identifies the class to which service is directed Identifies the instance to which service is directed Number of service data bytes for request Service data for request 2 91 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncWriteDnetExplMsg Write DeviceNet Explicit Message Function Description ncWriteDnetExplMsg writes an explicit message request using an Explicit Messaging Object The two most commonly used DeviceNet explicit messages are the Get Attribute Single service and the Set Attribute Single service The easiest way to execute the Get Attribute Single service on a remote device is to use the NI DNET ncGetDnetAttribute function The easiest way to execute the Set Attribute Single service on a remote device is to use the NI DNET ncSetDnetAttribute function To execute services other than Get Attribute Single and Set Attribute Single use the following sequence of function calls ncwriteDnetExp1
59. e 1 1 NI DNET Data Types NI DNET Data Type ANSI C LabVIEW DeviceNet Description NCTYPE_type_P NCTYPE_type N A N A Pointer to a variable with type type NCTYPE_INT8 signed char I8 SINT 8 bit signed integer NCTYPE_INT16 signed short 116 INT 16 bit signed integer NCTYPE_INT32 signed long 132 DINT 32 bit signed integer NCTYPE_UINT8 unsigned char U8 USINT 8 bit unsigned integer NCTYPE_UINT16 unsigned short U16 UINT 16 bit unsigned integer NCTYPE_UINT32 unsigned long U32 UDINT 32 bit unsigned integer NCTYPE_BOOL unsigned char TF Boolean BOOL Boolean value In ANSI C constants NC_TRUE 1 and NC_FALSE 0 are used for comparisons NCTYPE_STRING char array of abc string STRING ASCII character string characters terminated by null character 0 NCTYPE_REAL float SGL REAL 32 bit floating point NCTYPE_LREAL double DBL LREAL 64 bit floating point National Instruments Corporation 1 1 NI DNET Programmer Reference Manual Chapter 1 NI DNET Data Types Table 1 1 NI DNET Data Types Continued NI DNET Data Type ANSI C LabVIEW DeviceNet Description NCTYPE_ANY_P void N A N A Reference to variable of unknown type used in cases where actual data type can vary depending on particular context NCTYPE_OBJH unsigned long Type definition ncObjHandle ctl U32 N A Handle referring to an NI DNE
60. e Object is returned in Interface ObjHandle Out This handle is used with all subsequent function calls for that Interface Object Values The encoding of object handles is internal to NI DNET NI DNET Programmer Reference Manual 2 8 ni com Chapter 2 NI DNET Functions EasylOConfig Easy 10 Config Device ObjHandle Out Description If the Easy IO Config function is successful an array of I O Object handles is returned in Device ObjHandle Out This array can be indexed to retrieve individual I O handles for data read and write Values The encoding of object handles is internal to NI DNET Examples LabVIEW Open Interface Object DNETO using baud rate 125000 MAC ID 5 and poll mode Scanned Open two I O Objects with MAC ID 6 and 9 and start the communication National Instruments Corporation Device Configurations Interface Name interface ObiHandie out Device ObjHandile out Error out DeviceNet Interface Configuration 2 9 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncCloseObject Close ncCloseObject Close Purpose Close an NI DNET object Format LabVIEW ObjHandle in Error in C NCTYPE_STATUS ncCloseObject NCTYPE_OBJH ObjHandle Input ObjHandle Object handle of an open Interface Object Explicit Messaging Object or I O Object Output None Function Description The ncCloseObject function closes an NI DNET object when
61. e command line such as Explain OxBFF62001 and the utility displays the description Your application code should check the status returned from every NI DNET function If an error is detected you should close all NI DNET handles then exit the application If a warning is detected you can display a message for debugging purposes or simply ignore the warning Parameter Descriptions Status Description Status must contain a status value returned from a previous call to an NI DNET function You normally call ncStatustoString only when the status is nonzero indicating an error or warning condition Values Value of data type NCTYPE_STATUS returned from an NI DNET function call SizeofString Description SizeofString is the size of the buffer referenced by String The ncStatustoString function copies at most SizeofString bytes into the string and cuts off the text as needed You can normally obtain this size using the C language sizeof function Although you can often obtain an adequate description with fewer bytes a 512 byte buffer is large enough to hold any NI DNET status description Values sizeof buffer referenced by String NI DNET Programmer Reference Manual 2 84 ni com Chapter 2 NI DNET Functions ncStatusToString Status To String String Description Textual string which describes the function status The string is NULL terminated like any other C language string The numbe
62. e network The ReadAvail state clears when you call ncReadDnetExp1Msg An explicit message response is received only after you send an explicit message request using ncWriteDnetExp1Msg The following sequence of calls is typical ncWriteDnetExplMsg ncWaitForState ncReadDnetExp1Msg This sequence is used internally by ncGetDnetAttribute and ncSetDnetAttribute The ReadAvail state is not needed when using the explicit messaging functions ncGetDnetAttribute and ncSetDnetAttribute because both of these functions wait for the explicit message response internally For the Explicit Messaging Object the Established state is clear not established before you start communication using ncOperateDnetIntf After you start communication the Established state remains clear until the explicit message connection has been successfully established with the remote DeviceNet device After the explicit message connection has been established the Established state sets and remains set for as long as the explicit message connection is open Until the Established state sets for the Explicit Messaging Object all calls to ncGetDnetAttribute ncSetDnetAttribute or ncWriteDnetExp1Msg return the error CanErrNotStarted Before you call any of these functions in your application you must first wait for the Established state to set After the Established state is set unless communication problems occur with the device CanErrFunctionTime
63. eNet data in the following functions e ncWriteDnetIO Specification for your device s output assembly e ncSetDnetAttribute Data type of the attribute Unless the attribute s DeviceNet data type is a structure or array the value for ByteOffset is always 0 e ncWriteDnetExplMsg Specification for the service data of the explicit message request Values 0 to 255 8 TF in Description If the selected Dnet Type is BOOL this input terminal provides the LabVIEW data to convert into a DeviceNet data member The LabVIEW data type for this input terminal is an array of eight LabVIEW Booleans indicated as 8 TF You can index into this array to change specific Boolean members The Boolean at index zero is the least significant bit bit 0 the Boolean at index one is the next least significant bit 1 and so on Values LabVIEW data to convert into a DeviceNet data member 132 116 18 in Description If the selected Dnet Type is SINT INT or DINT this input terminal provides the LabVIEW data to convert into a DeviceNet data member Although the LabVIEW data type for this input terminal is 132 it can be coerced automatically from 116 or 18 Values LabVIEW data to convert into a DeviceNet data member National Instruments Corporation 2 15 NI DNET Programmer Reference Manual NI DNET Functions ncConvertForDnetWrite Convert For DeviceNet Write U32 U16
64. ect Since each I O Object continuously acquires input data from the DeviceNet network you normally wait for new input to become available prior to calling ncReadDnet 10 By waiting for new input data your application can handle I O data at the same rate as the DeviceNet I O communication You can use the function ncCreateNotification C only or ncWaitForState C or LabVIEW to wait for new input data ncReadDnet IO normally returns input data bytes obtained from the input assembly of a remote DeviceNet slave device The format of this input assembly is normally documented either by the device vendor or within the DeviceNet Specification itself The bytes of a device s input assembly often consist of multiple data members rather than a single value For C you can often obtain each data member from the input bytes by using NI DNET Programmer Reference Manual 2 72 ni com Chapter 2 NI DNET Functions ncReadDnetlO Read DeviceNet 1 0 typecasting For LabVIEW you can often obtain each data member from the input bytes using the ncConvertFromDnetRead function For more information on input assemblies and how to obtain individual data members refer to the NJ DNET User Manual Parameter Descriptions ObjHandle Description Obj Handle must contain an object handle returned from ncOpenDnet Io In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls
65. ect referenced by objh NCTYPE_STATUS status NCTYPE_OBJH objh NCTYPE_VERSION swver status ncGetDriverAttr objh NC_ATTR_SOFTWARE_VERSION sizeof swver amp Swver NI DNET Programmer Reference Manual 2 44 ni com Chapter 2 NI DNET Functions ncOpenDnetExplMsg Open DeviceNet Explicit Messaging ncOpenDnetExpIMsg Open DeviceNet Explicit Messaging Purpose Configure and open an NI DNET Explicit Messaging Object Format LabVIEW Interface Name ObjHandle out Device MaclD 0 63 Error in Error out C NCTYPE_STATUS ncOpenDnetExp1Msg NCTYPE_STRING IntfName NCTYPE_UINT32 DeviceMacId NCTYPE_OBJH_P ObjHandle Input Int fName Name of DeviceNet interface DeviceMacId MAC ID of the remote device Output ObjHandle Object handle you use with all subsequent function calls for the Explicit Messaging Object Function Description ncOpenDnetExp1Msg configures and opens an NI DNET Explicit Messaging Object and returns a handle that you use with all subsequent function calls for that object The Explicit Messaging Object represents an explicit messaging connection to a remote DeviceNet device Since only one explicit messaging connection is created for a given device the Explicit Messaging Object is also used for features which apply to the device as a whole Use the Explicit Messaging Object to do the following e Execute the DeviceNet Get Attribute Single service on the remote device ncGetDnetAtt
66. endor ID attribute of device s Identity Object This attribute verifies that the device is the same one expected by your application If the Vendor ID does not match NI DNET returns the error DnetErrDevInitVendor The Vendor ID is a number assigned to the device vendor by the Open Device Vendor s Association ODVA If you do not call ncSetDriverattr to set the Vendor ID a default value of zero is used When Vendor ID is zero NI DNET does not verify the device s Vendor ID National Instruments Corporation 3 5 NI DNET Programmer Reference Manual Chapter 3 NI DNET Objects Interface Object Interface Object Description The Interface Object represents a DeviceNet interface Since this interface acts as a device on the DeviceNet network much like any other device it is configured with its own MAC ID and baud rate Use the Interface Object to do the following e Configure NI DNET settings that apply to the entire interface e Start and stop communication for all NI DNET objects associated with the interface The Interface Object must be the first NI DNET object opened by your application and thus the ncOpenDnetiInt f function must be the first NI DNET function called by your application Functions Function Name Function Description EasylOClose Close multiple NI DNET objects LabVIEW only EasylOConfig Configure and open multiple NI DNET objects LabVIEW only
67. ength NI DNET Programmer Reference Manual 2 26 ni com Chapter 2 NI DNET Functions ncCreateNotitication Create Notification ncCreateNotification Create Notification Purpose Create a notification callback for an object C only Format LabVIEW Not applicable C NCTYPE_ STATUS ncCreateNotification NCTYPE_OBJH ObjHandle NCTYPE_STATE DesiredState NCTYPE DURATION Timeout NCTYPE_ANY_P RefData NCTYPE_NOTIFY_CALLBACK Callback Input ObjHandle Object handle of an open Explicit Messaging Object or T O Object DesiredState States for which notification is called Timeout Number of milliseconds to wait for one of the desired states RefData Pointer to user specified reference data Callback Address of your callback function Output None Function Description ncCreateNotification creates a notification callback for the object specified by ObjHandle The NI DNET driver uses the notification callback to communicate state changes to your application The ncCreateNotification function does not apply to LabVIEW programming You commonly use ncCreateNotification to receive notifications when new input data is available for an I O Object Within your notification callback function you call ncReadDnet IO to read the new input data perform any needed calculations for that data call ncwriteDnetIo to provide output data then return from the callback function National Instruments Corporation 2 27 NI DNET Progr
68. er 2 NI DNET Functions NCTYPE_STATUS signed long 132 N A For ANSI C this represents the status returned from NI DNET functions Refer to ncStatusToString for more information For LabVIEW NI DNET functions use the standard error clusters for status information National Instruments Corporation 1 3 NI DNET Programmer Reference Manual NI DNET Functions This chapter lists all NI DNET functions and describes the purpose format parameters and return status for each function All the NI DNET functions are reentrant to achieve good multitasking performance Unless otherwise stated each NI DNET function suspends execution of your program until it completes Using the Function Descriptions This chapter lists the NI DNET functions alphabetically The description of each function is structured as follows Purpose States the function s purpose Format Describes the function s format for the LabVIEW and C including C programming languages Input Lists the function s input parameters values passed into the function Output Lists the function s output parameters values passed out of the function Function Description Provides details about the function s purpose and effect Parameter Description Provides details about each input output parameter including allowed values and their meanings National Instruments Corporation 2 1 NI DNET Programmer Reference
69. erence Manual 2 54 ni com Chapter 2 NI DNET Functions ncOpenDnetiO Open DeviceNet 1 0 Function Description ncOpenDnet 10 configures and opens an NI DNET I O Object and returns a handle that you use with all subsequent function calls for that object The I O Object represents an I O connection to a remote DeviceNet device The I O Object usually represents I O communication as a master with a remote slave device If your computer is essentially being used as the primary controller of your DeviceNet devices you should configure I O communication as a master You can also configure the I O Object for I O communication as a slave with a remote master If your computer is essentially being used as a peripheral device for another primary controller you can configure I O communication as a slave This is done by setting the T O Object s DeviceMacId to the same MAC ID as the Interface Object Int fMacId parameter of ncOpenDnet Int f The I O Object supports as many master slave I O connections as currently allowed by the DeviceNet Specification version 2 0 This means that you can use polled strobed and COS cyclic I O connections simultaneously for a given device As specified by the DeviceNet Specification you can only use one master slave I O connection of a given type for each device MAC ID For example you cannot open two polled I O connections for the same device Use the I O Object to do the following e Read data from the
70. evice s documentation Values Error codes from the device s error response NI DNET Programmer Reference Manual 2 40 ni com Examples LabVIEW Get the Serial Number attribute using an Explicit Messaging Object The Serial Number is contained in the Identity Object class ID 1 instance ID 1 attribute ID 6 The DeviceNet data type for Device Type is UDINT for which the LabVIEW data type U32 should be used The Timeout is 100 ms C Chapter 2 NI DNET Functions ncGetDnetAttribute Get DeviceNet Attribute Error in Timeout ObjHandie in Classid ObjHandie out Instanceld Attributeld EH Error out ctual ttrD ataLenath Get the Device Type attribute using the Explicit Messaging Object referenced by objh The Device Type is contained in the Identity Object class ID 1 instance ID 1 attribute ID 2 The DeviceNet data type for Device Type is UINT for which the NI DNET data type NC1 NC1 NC1 NC1 NC1 NC1 TYPE_STATUS TYPE _OBJH TYPE _UINT16 TYPE _UINT16 TYPE _UINT16 YPE_UINT16 should be used status objh device_type actual_length device_error status ncGetDnetAttribute objh 0x01 0x01 0x02 100 National Instruments Corporation sizeof device type amp device_type amp actual_length amp device_error 2 41 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncGetDriverAttr Get Driver Attribute ncGetD
71. eviceNet Explicit Messaging 0 00 0 eeeeeeseeseeereeeee 2 45 ncOpenDnetIntf Open DeviceNet Interface ss 2 48 ncOpenDnetIO Open DeviceNet I O ss 2 54 ncOperateDnetIntf Operate DeviceNet Interface 2 64 ncReadDnetExpIMsg Read DeviceNet Explicit Message 0 eee ee eeeeseeeeereeeeeeees 2 68 ncReadDnetIO Read DeviceNet I O cccccecessccesseceeeneceeeneeeseneeessneeesssseeeseeeeseaeeeees 2 72 ncSetDnetAttribute Set DeviceNet Attribute 0 cccceccceessseceeseeeeenseeesneeessseeeneeeeees 2 75 ncSetDriverAttr Set Driver Attribute ss 2 80 ncStatusToString Status To String ss 2 83 ncWaitForState Wait For State sise 2 86 ncWriteDnetExplMsg Write DeviceNet Explicit Message 2 91 ncWriteDnetIO Write DeviceNet O ss 2 95 National Instruments Corporation v NI DNET Programmer Reference Manual Contents Chapter 3 NI DNET Objects Explicit Messaging Object inin inaa vocas eds epdes estate tee 3 2 Interface Objects sement instant soba cosa dab o eei 3 6 TWO Objects ni ahegan tases desasdut hak cuaassbesodascsasecas shies urnes tt es asaeteneedecy 3 9 Appendix A Technical Support and Professional Services Glossary Index NI DNET Programmer Reference Manual vi www ni com About This Manual This manual is a programming reference for functions objects and data types in the NI DNET software for Windows This manual assumes that you are already familiar with the Windows system How to Use t
72. f using the LabVIEW stop button from the menu bar National Instruments Corporation 2 7 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions EasylOConfig Easy 10 Contig Parameter Descriptions Interface Name Description Name of the DeviceNet interface as an ASCII string with format DNETx where x is a decimal number starting at zero that indicates which DeviceNet interface is being used You associate DeviceNet interface names with physical ports using Measurement and Automation Explorer MAX Values DNETO DNET1 DNET31 In LabVIEW you select the interface name from an enumerated list Device Configurations Description Array of NI DNET I O Object configuration clusters For a description of individual elements within the I O cluster refer to the ncOpenDnet IO parameter description Values Refer to the ncOpenDnet IO input parameters description for value range applicable to each configuration parameter Interface Configuration Description Configuration cluster for NI DNET Interface Object For a description of individual elements within the interface cluster refer to the ncOpenDnetIntf parameter description Values Refer to the ncOpenDnet Int input parameters description for allowed values for each cluster element Interface ObjHandle Out Description If the Easy IO Config function is successful a handle to the newly opened Interfac
73. f ncWriteDnetExplMsg or DnetData in input terminal of a subsequent use of this function NI DNET Programmer Reference Manual 2 16 ni com Chapter 2 NI DNET Functions ncConvertForDnetWrite Convert For DeviceNet Write Examples LabVIEW 1 Use ncwriteDnet1o to write Command Assembly to a Position Controller In this output assembly the byte at offset 0 consists of 8 BOOL and the bytes at offset 4 7 consist of a Target Position of type DINT Use ncConvertForDnetWrite to convert appropriate LabVIEW data types for these DeviceNet data members Byte Offset DINT 132 Replace Array Element ObjHandie in ObsHandile out Error in Write DeviceNet IO vi Error out 2 Set an attribute Foo using the ncSetDnetAttribute function The attribute Foo is contained in an object with class ID D5 hex instance ID 1 attribute ID 5 and its DeviceNet data type is LREAL Use ncConvertForDnetWrite to convert the appropriate LabVIEW data type for Foo National Instruments Corporation 2 17 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncConvertForDnetWrite Convert For DeviceNet Write ByteOffset LREAL DBLI ol Dnet Data Inj Lus Convert For DeviceNet Write vi ObjiHandie in ObjiHandie out Instanceld E Error in Error out Set DeviceNet Attribute vi C 1 Demonstrate the same conversions as LabVIEW example 1 NCTYPE_UINT8 data 8 NCTYPE_
74. g photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation National Instruments respects the intellectual property of others and we ask our users to do the same NI software is protected by copyright and other intellectual property laws Where NI software may be used to reproduce software or other materials belonging to others you may use NI software only to reproduce materials that you may reproduce in accordance with the terms of any applicable license or other legal restriction Trademarks National Instruments NI ni com and LabVIEW are trademarks of National Instruments Corporation Refer to the Terms of Use section on ni com legal for more information about National Instruments trademarks Other product and company names mentioned herein are trademarks or trade names of their respective companies Members of the National Instruments Alliance Partner Program are business entities independent from National Instruments and have no agency partnership or joint venture relationship with National Instruments 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
75. he MAC ID for you This utility configurator is described in the NI DNET User Manual Values 0 to 63 ObjHandle Description If the ncOpenDnetExp1Msg function is successful a handle to the newly opened Explicit Messaging Object is returned in ObjHandle This handle is used with all subsequent function calls for that Explicit Messaging Object The functions most commonly used with the Explicit Messaging Object are ncGetDnetAttribute and ncSetDnetAttribute Values The encoding of Obj Hand1e is internal to NI DNET NI DNET Programmer Reference Manual 2 46 ni com Chapter 2 NI DNET Functions ncOpenDnetExplMsg Open DeviceNet Explicit Messaging Examples LabVIEW Open an Explicit Messaging Object using interface DNET2 and device MAC ID 15 Interface Name ObjiHandie out TI Device MaciD CNRS Error in Error out Open an Explicit Messaging Object using interface DNETO and device MAC ID 12 NCTYPE_STATUS status NCTYPE_OBJH objh status ncOpenDnetExplMsg DNETO 12 amp objh National Instruments Corporation 2 47 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetintf Open DeviceNet Interface ncOpenDnetintf Open DeviceNet Interface Purpose Configure and open an NI DNET Interface Object Format LabVIEW Interface Name ObjHandle out DeviceNet Network Interface i
76. he Manual Set Installation Guide Software and Hardware Installation Experienced First Time Poe NI DNET Users NR NI DNET User Manual NI DNET Function Programmer and Object ae Reference ete Application Manual Descriptions Development and Examples LL J Use the installation guide to install and configure your DeviceNet hardware and NI DNET software Use the NI DNET User Manual to learn the basics of NI DNET and how to develop an application The user manual also contains information about DeviceNet hardware Use this NI DNET Programmer Reference Manual for specific information about each NI DNET function and object National Instruments Corporation vij NI DNET Programmer Reference Manual About This Manual Conventions bold italic monospace monospace italic The following conventions appear in this manual The symbol leads you through nested menu items and dialog box options to a final action The sequence File Page Setup Options directs you to pull down the File menu select the Page Setup item and select Options from the last dialog box This icon denotes a note which alerts you to important information Bold text denotes items that you must select or click in the software such as menu items and dialog box options Bold text also denotes parameter names Italic text denotes variables emphasis a
77. ime using ncGetDriverAttr but never set it Set You can get the attribute at any time using ncGetDriverAttr You can set the attribute using ncSetDriverAttr but only prior to starting communication using ncOperateDnetIntf National Instruments Corporation 3 1 NI DNET Programmer Reference Manual Chapter 3 NI DNET Objects Explicit Messaging Object Explicit Messaging Object Description The Explicit Messaging Object represents an explicit messaging connection to a remote DeviceNet device physical device attached to your interface by a DeviceNet cable Since only one explicit messaging connection is created for a given device the Explicit Messaging Object is also used for features that apply to the device as a whole Use the Explicit Messaging Object to do the following e Execute the DeviceNet Get Attribute Single service on the remote device ncGetDnetAttribute e Execute the DeviceNet Set Attribute Single service on the remote device ncSetDnetAttribute e Send any other explicit message requests to the remote device and receive the associated explicit message response ncWriteDnetExp1Msg ncReadDnetExplMsg e Configure NI DNET settings that apply to the entire remote device Functions Function Name Function Description ncCloseObject Close an NI DNET object ncConvertForDnetWrite Convert an appropriate LabVIEW data type for writing data bytes on the DeviceNet network ncConve
78. ines the rate of production for the poll command messages NI DNET Programmer Reference Manual 2 60 ni com Chapter 2 NI DNET Functions ncOpenDnetiO Open DeviceNet 1 0 ExpPacketRate Continued Description Continued Poll with Scanned poll mode When using the Scanned poll mode since all poll and strobe requests are produced at the same time you normally set the ExpPacketRate for all polled strobed I O Objects to a common value If you need to isolate devices that are slow to respond to poll requests it is possible to use different ExpPacketRate values while still maintaining the benefits of scanned I O You can set all ExpPacketRate values for polled I O Objects as two groups one foreground group and a second background group whose ExpPacketRate is an exact multiple of the foreground group s All strobed I O must use the same rate as the foreground group for polled I O For example you can set some polled I O and all strobed I O to a common foreground rate of 100 ms and other polled I O to a background rate of 500 ms To maintain overall network determinism the background poll requests are interspersed evenly among each foreground scan Poll with Individual poll mode When using the Individual poll mode the ExpPacketRate determines the rate at which the poll request of each polled I O Object is produced Although all strobed I O Objects must still use the same rate each polled I O Object comm
79. ion Output data The format of these output bytes is specific to your DeviceNet device Values Output data bytes NI DNET Programmer Reference Manual 2 96 ni com Chapter 2 NI DNET Functions ncWriteDnetlO Write DeviceNet 1 0 Examples LabVIEW Write 4 output bytes to an I O Object ObjiHandie in ObjiHandie out Error in Error out C Write 10 output bytes to the I O Object referenced by objh NCTYPE_STATUS status NCTYPE_OBJH objh NCTYPE_UINT8 output 10 status ncWriteDnetIO objh 10 output National Instruments Corporation 2 97 NI DNET Programmer Reference Manual NI DNET Objects This chapter describes each NI DNET object lists the functions which can be used with the object and describes each of the object s driver attributes The description of each object is structured as follows Description Gives an overview of the major features and uses of the object Functions Lists each NI DNET function which can be used with the object For information on how each NI DNET function is used with the object refer to Chapter 2 NJ DNET Functions Driver Attributes Lists and describes the NI DNET driver attributes for each object The driver attributes are listed in alphabetical order For each driver attribute the description lists its data type attribute ID and permissions Driver attribute permissions consist of one of the following Get You can get the attribute at any t
80. ip between expected packet rate EPR and the Po11Mode parameter of the Interface Object is the same as discussed in the ncOpenDnet Int f and ncOpenDnetIO function descriptions For example if you configure the Interface Object in Scanned mode you must configure all the strobe connections with the same EPR and all the poll connections with either the same EPR value or an integer multiple of it If this is not the case you will see an Inconsistent Parameter error Since the EasyIOConfig function also starts the interface a call to ncOperateDnetIntf for Start is only needed if the communication needs to be interrupted in the middle of your application to set some driver attributes for an object To do so call ncOperateDnetIntf with Stop as the Opcode after calling EasyIlOConfig make necessary calls to ncSetDriverAttr and then call ncOperateDnetIntf with Start as the Opcode to restart the communication To open an Explicit Messaging Object call ncOpenDnetExp1Msg separately after a call to EasylOConfig iS Note For any NI DNET LabVIEW application make sure that all the open calls are matched by an equal number of close calls For example if you have called the Open DeviceNet Interface function twice you must call the Close Object function twice as well passing in the handles returned from the open interface calls Also to ensure proper closure of all NI DNET objects create your own stop button to stop your application instead o
81. iverAttr Set Driver Attribute ncSetDriverAttr only applies to the NI DNET software on your computer and cannot be used to set an attribute in a remote DeviceNet device To set an attribute in a remote DeviceNet device use ncSetDnetAttribute Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from ncOpenDnetExp1Msg ncOpenDnetIntf or ncOpenDnetIO In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the object Values The encoding of ObjHandle is internal to NI DNET Attrid Description Identifier of the NI DNET attribute For each NI DNET object a list of supported attribute identifiers is provided in Chapter 3 NI DNET Objects Values 80000000 to 8000FFFF hex high bit differentiates from DeviceNet IDs SizeofAttr Description For C SizeofAttr is the size of the buffer referenced by Attr It is used to verify that the Attr buffer is large enough to hold the attribute s new value This size is normally obtained using the C language sizeof function For LabVIEW since Attr is obtained directly as an input this size is not needed Values sizeof buffer referenced by Attr Attr Description New attribute value The value is usually provided in an unsigned 32 bit integer and thus At tr is of type NCTYPE_UINT32_P Values New value of NI DNET attribute National Instr
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83. mmunication as a slave this setting is ignored because the remote master determines the expected packet rate on behalf of your slave I O connection Values 1 to 60000 ObjHandle Description If the ncOpenDnet1Io function is successful a handle to the newly opened I O Object is returned in ObjHandle This handle is used with all subsequent function calls for that I O Object The functions most commonly used with the I O Object are ncReadDnet 10 and ncWriteDnetIo Values The encoding of ObjHand1e is internal to NI DNET Examples LabVIEW Open an I O Object using interface DNET2 device MAC ID 15 connection type Poll input length 14 output length 6 and expected packet rate 40 ms ObjiHandie out Device MaclD 0 63 15 POLL Error out NI DNET Programmer Reference Manual 2 62 ni com Chapter 2 NI DNET Functions ncOpenDnetiO Open DeviceNet 1 0 C Open an I O Object using interface DNETO device MAC ID 12 connection type Strobe input length 2 output length 1 and expected packet rate 100 ms NCTYPE_STATUS status NCTYPE_OBJH objh status ncOpenDnetIO DNETO 12 NC_CONN_STROBE 2 1 100 amp objh 7 G E National Instruments Corporation 2 63 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOperateDnetintf Operate DeviceNet Interface ncOperateDnetintf Operate DeviceNet Interface
84. most recent message received on the I O connection ncReadDnetIO e Write data for the next message produced on the I O connection ncWriteDnetI0 Parameter Descriptions IntfName Description Name of the DeviceNet interface as an ASCII string with format DNETx Where x is a decimal number starting at zero that indicates which DeviceNet interface is being used You associate DeviceNet interface names with physical ports using Measurement amp Automation Explorer MAX Values DNETO DNET1 DNET31 In LabVIEW you select the interface name from an enumerated list The LabWindows CVI function panel also provides an enumerated list National Instruments Corporation 2 55 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetlO Open DeviceNet 1 0 DeviceMacld Description MAC ID device address of the remote DeviceNet device Many devices use physical switches to set their MAC ID For such devices you can usually determine the device s MAC ID by examining those switches MAC ID 63 is usually reserved for new devices many devices use 63 as the factory default If you do not know the MAC ID of your DeviceNet device NI DNET provides a utility which can display the MAC ID for you This utility Configurator is described in the NI DNET User Manual For I O communication as a master to a remote slave device the usual case DeviceMacTd is the MAC ID of the rem
85. n C NCTYPE_STATUS ncGetDnetAttribute NCTYPE_OBJH ObjHandle NCTYPE_UINT16 ClassId NCTYPE_UINT16 Instanceld NCTYPE_UINTS8 Attributeld NCTYPE_DURATION Timeout NCTYPE_UINT16 SizeofAttrData NCTYPE_ANY_P AttrData NCTYPE_UINT16_P ActualAttrDataLength NCTYPE_UINT16_P DeviceError Input ObjHandle Object handle of an open Explicit Messaging Object ClassId Identifies the class which contains the attribute Instanceld Identifies the instance which contains the attribute Attributeld Identifies the attribute to get Timeout Maximum time to wait for response from device SizeofAttrData Size of AttrData buffer in bytes C only Output AttrData Attribute value received from device ActualAttrDataLength DeviceError NI DNET Programmer Reference Manual Actual number of attribute data bytes returned Error codes from device error response 2 36 ni com Function Description Chapter 2 NI DNET Functions ncGetDnetAttribute Get DeviceNet Attribute ncGetDnetAttribute gets the value of an attribute from a DeviceNet device using an Explicit Messaging Object ncGetDnetAttribute executes the Get Attribute Single service on a remote DeviceNet device The format of the data returned in AttrData is defined by the DeviceNet data type in the attribute s description When using LabVIEW the ncConvertFromDnetRead function can convert this DeviceNet data type into an appropriate LabVIEW data type When using C AttrData can point to a
86. n as a single byte Values Poll COS and Cyclic 0 to 255 Strobe as master DeviceMacId not equal to Int fMacId 0 to 8 Strobe as slave DeviceMacId equal to Int fMacId 1 NI DNET Programmer Reference Manual 2 58 ni com Chapter 2 NI DNET Functions ncOpenDnetiO Open DeviceNet 1 0 OutputLength Description Number of output bytes for the I O connection This is the number of bytes written to the I O connection using the ncWriteDnetIo function The following information is specific to the ConnectionType setting Poll cos and Cyclic For these I O connections types the output length is the same as the number of bytes produced to the remote device Strobe as master DeviceMacId not equal to Int fMacId For this I O connection the output length must have a value of 1 The output data consists of a single Boolean value bit which is placed into the strobe command message using DeviceMacId This Boolean value is provided to the ncWriteDnet Io function as a single byte Strobe as slave DeviceMacId equal to Int MacId For this I O connection the output length must have a value from 0 to 8 The output length is the same as the number of bytes produced in the strobe response message Values Poll COS and Cyclic 0 to 255 Strobe as master DeviceMacId not equal to Int f MacId 1 Strobe as slave DeviceMacId equal to IntfMacId 0 to 8 National Instruments Corporation 2 59 NI DNET P
87. n Determines the communication scheme used for all polled T O connections in which the interface acts as a master The poll mode determines the overall scheme used to transmit poll requests to slave devices Automatic The default poll mode is Automatic Use this mode if you do not want to specify exact timing for polled and strobed T O connections In Automatic mode the NI DNET software automatically calculates a safe rate for production of all poll requests and strobe requests This mode is similar to Scanned mode except that you do not need to specify a valid ExpPacketRate for each polled strobed I O Object ExpPacketRate is ignored If you use Automatic you cannot call the ncOpenDnet 10 function while communicating after ncOperateDnetInt with Start because the automatic rate calculation occurs during Start Use Scanned or Individual if you need to open I O connections while communicating NI DNET Programmer Reference Manual 2 50 ni com PollMode Continued Chapter 2 NI DNET Functions ncOpenDnetintf Open DeviceNet Interface Description Continued Scanned This mode enables the traditional scanned I O scheme for polled and strobed I O connections In Scanned mode all poll requests and strobe requests are produced in quick succession then NI DNET waits to receive individual responses The benefits of scanned I O are reduced overhead and improved overall determinism on the DeviceNet net
88. n it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire 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 includin
89. on constant NC_DURATION_INFINIT GI wa CurrentState Description Current state of the object If one of the desired states occurs it provides the current value of the ReadAvail and Established states If the Timeout expires before one of the desired states occurs it has the value 0 Values 0 desired states did not occur or A combination of one or more of the following bit values 1 hex ReadAvail constant NC_ST_READ_AVAIL 8 hex Established constant NC_ST_ESTABLISHED National Instruments Corporation 2 89 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncWaitForState Wait For State Examples LabVIEW Wait up to 10 seconds for the ReadAvail state of an Explicit Messaging Object ObsHandie in ObjiHandie out Read Available Error in 10000 Error out C Wait up to 10 seconds for the ReadAvail state of the Explicit Messaging Object referenced by objh NCTYPE_STATUS status NCTYPE_OBJH objh NCTYPE_STATE currstate status ncWaitForState objh NC_ST_READ AVAIL 10000 amp currstate NI DNET Programmer Reference Manual 2 90 ni com Chapter 2 NI DNET Functions ncWriteDnetExplMsg Write DeviceNet Explicit Message ncWriteDnetExpiMsg Write DeviceNet Explicit Message Purpose Write an explicit message request using an Explicit Messaging Object Format LabVIEW C NCTYPE_STATUS Input ObjHandl
90. orts as many master slave I O connections as currently allowed by the DeviceNet Specification version 2 0 This means that you can use polled strobed and COS cyclic I O connections simultaneously for a given device As specified by the DeviceNet Specification only one master slave I O connection of a given type can be used for each device MAC ID For example you cannot open two polled I O connections for the same device Use the I O Object to do the following e Read data from the most recent message received on the I O connection ncReadDnetIO e Write data for the next message produced on the I O connection ncWriteDnetI0 Functions Function Name Function Description EasyIOClose Close multiple NI DNET objects LabVIEW only EasylOConfig Configure and open multiple NI DNET objects LabVIEW only ncCloseObject Close an NI DNET object ncConvertForDnetWrite Convert an appropriate LabVIEW data type for writing data bytes on the DeviceNet network ncConvertFromDnetRead Convert data read from the DeviceNet network into an appropriate LabVIEW data type ncCreateNotification Create a notification callback for an object C only National Instruments Corporation 3 9 NI DNET Programmer Reference Manual Chapter 3 NI DNET Objects 1 0 Object Functions Continued Function Name Function Description ncGetDriverAttr Get the value of an attribute in the NI DNET driver ncO
91. ot need to wait for a specific state Device Type Attribute ID NC_ATTR_DEVICE_TYPE Hex Encoding 80000084 Data Type NCTYPE_UINT16 Permissions Set Description Device Type of the device as reported in the Device Type attribute of device s Identity Object This attribute verifies that the device is the same one expected by your application If the Device Type does not match NI DNET returns the error DnetErrDevInitDevType The Device Type indicates conformance to a specific device profile such as Photoelectric Sensor or Position Controller If you do not callncSetDriveraAttr to set the Device Type a default value of zero is used When Device Type is zero NI DNET does not verify the device s Device Type National Instruments Corporation 3 3 NI DNET Programmer Reference Manual Chapter 3 NI DNET Objects Explicit Messaging Object Keep Explicit Messaging Attribute ID NC_ATTR_KEEP_EXPL MSG Hex Encoding 80000099 Data Type NCTYPE_BOOL Permissions Set Description To properly close I O connections in the remote device when ncCloseObject is called NI DNET must ensure that an explicit messaging connection to the device remains open When this attribute is set to NC_TRUE the default NI DNET sends a nonoperational request a ping to the device every few seconds to ensure that the explicit messaging connection does not timeout When this attribute is NC_FALSE NI DNET
92. ote DeviceNet slave device and thus must be different than the MAC ID of your DeviceNet interface If you want to configure I O communication as a slave with a remote master set DeviceMacId to the same MAC ID as your DeviceNet interface the Int fMacId parameter of your previous call to ncOpenDnet Int f By associating the I O Object with your DeviceNet interface in this manner you indicate that it represents T O communication as a slave Values 0 to 63 NI DNET Programmer Reference Manual 2 56 ni com ConnectionType Chapter 2 NI DNET Functions ncOpenDnetiO Open DeviceNet 1 0 Description Type of master slave I O connection The connection type is either Polled Strobed change of state COS or Cyclic As specified by the DeviceNet Specification you can use only one master slave T O connection of a given type for each device MAC ID For example you cannot open two polled I O connections for the same device If you do not know the I O connection types supported by your DeviceNet device NI DNET provides a utility which queries the device for both this information and the device s supported input and output lengths This utility configurator is described in the NI DNET User Manual Change of state COS and cyclic I O connections are acknowledged by default If you want to suppress acknowledgments for these I O connections set the Ack Suppress driver attribute to true prior to starting communic
93. ough bytes available to store the attribute data This size is normally obtained using the C language sizeof function and has no direct relation to the number of bytes received on the network For LabVIEW since the buffer for AttrData is allocated automatically by NI DNET this size is not needed The number of bytes allocated for AttrData should be large enough to hold the maximum number of data bytes defined for the attribute Values sizeof buffer referenced by AttrData AttrData Description Attribute value received from device The format of the data returned in AttrData is defined by the DeviceNet data type in the attribute s description When using LabVIEW the ncConvertFromDnetRead function can convert this DeviceNet data type into an appropriate LabVIEW data type When using C AttrData can point to a variable of the appropriate data type as specified in Chapter 1 NI DNET Data Types The number of attribute data bytes returned is the smaller of SizeofAttrData and ActualAttrDataLength Values Attribute data bytes ActualAttrDataLength Description Actual number of attribute data bytes returned This length is obtained from the actual Get Attribute Single response message If this length is greater than SizeofAttrData only SizeofAttrData bytes are returned in Att rDataa If this length is less than or equal to SizeofAttrData ActualAttrDataLength bytes are valid in AttrData
94. out it remains set until you stop communication using ncOperateDnetIntf While waiting for one of the above states if an error occurs such as a communication error or an initialization error the wait returns immediately with the appropriate error code For example if you call ncWaitforState with DesiredState of ReadAvail the wait function will return when data is available for a read or when a DeviceNet communication error such as connection timeout is detected NI DNET Programmer Reference Manual 2 88 ni com DesiredState C Chapter 2 NI DNET Functions ncWaitForState Wait For State ontinued Values A combination of one or more of the following bit values 1 hex ReadAvail constant NC_ST_READ_AVAIL 8 hex Established constant NC_ST_ESTABLISHED In LabVIEW and the LabWindows CVI function panel to facilitate combining multiple states you can select a valid combination from an enumerated list of all valid combinations This list contains the names of each state in the combination such as ReadAvail or Established Timeout Description Number of milliseconds to wait for one of the desired states If the timeout expires before one of the desired states occurs ncWaitForState returns a status of BFF62001 hex CanErrFunctionTimeout The special timeout value of FFFFFFFF hex is used to wait indefinitely Values 1 to 200000 or FFFFFFFF hex infinite durati
95. penDnetIO Configure and open an NI DNET I O Object ncReadDnetIO Read input data from an I O Object ncSetDriverAttr Set the value of an attribute in the NI DNET driver ncStatusToString Convert status returned from an NI DNET function into a descriptive string C only ncWaitForState Wait for one or more states to occur in an object ncWriteDnetIO Write output data to an I O Object Driver Attributes Ack Suppress Attribute ID NC_ATTR_ACK_SUPPRESS Hex Encoding 8000009A Data Type NCTYPE_BOOL Permissions Set Description This driver attribute applies only to change of state COS or cyclic I O connections ConnectionType of COS or Cyclic It determines whether acknowledgments are used false or suppressed true Acknowledgments are used with COS or cyclic I O connections to verify that produced data is received successfully When InputLength is nonzero the acknowledgment is produced by NI DNET When OutputLength is nonzero the acknowledgment is consumed by NI DNET If you do not callncSetDriverAttr to setAck Suppress a default value of false is used When successful device operation can be verified by other means COS or cyclic acknowledgment can often be suppressed For example if you open a polled I O connection in addition to the COS or cyclic I O connection you can set Ack Suppress to true If the ConnectionType of this I O object is Poll or Strobe the Ack Suppress attribu
96. r of bytes returned is the smaller of SizeofString and the number of bytes contained in the actual description Values Textual string which describes the function status Example C Check the status returned from the ncOpenDnetInt function and if not success print a descriptive string NCTYPE_STATUS NCTYPE_OBJH char status objh descr 1024 status ncOpenDnetIntf DNETO 0 125000 NC_POLL_AUTO if status DnetSuccess National Instruments Corporation amp objh ncStatustoString status sizeof descr descr printf ncOpenDnetIntf s n descr 2 85 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncWaitForState Wait For State ncWaitForState Wait For State Purpose Wait for one or more states to occur in an object Format LabVIEW ObjHandle in ObjHandle out Desired State Current State Timeout rms Error out Error in C NCTYPE_STATUS ncWaitForState NCTYPE_OBJH ObjHandle NCTYPE_STATE DesiredState NCTYPE_DURATION Timeout NCTYPE_STATE_P CurrentState Input ObjHandle Object handle of an open Explicit Messaging Object or an I O Object DesiredState States to wait for Timeout Number of milliseconds to wait for one of the desired states Output CurrentState Current state of object Function Description Use ncWaitforState to wait for one or more states to occur in the object specified by ObjHandle ncWaitforState is commonly used
97. ration G 5 NI DNET Programmer Reference Manual Index C conventions used in the manual viii D data types 1 1 NCTYPE_ANY_P 1 2 NCTYPE_ATTRID 1 2 NCTYPE_BOOL 1 1 NCTYPE_DURATION 1 2 NCTYPE_INT16 1 1 NCTYPE_INT32 1 1 NCTYPE_INTS8 1 1 NCTYPE_LREAL 1 1 NCTYPE_OBJH 1 2 NCTYPE_OPCODE 1 3 NCTYPE_REAL 1 1 NCTYPE_STATE 1 3 NCTYPE_STATUS 1 3 NCTYPE_STRING 1 1 NCTYPE_type_P 1 1 NCTYPE_UINT16 1 1 NCTYPE_UINT32 1 1 NCTYPE_UINTS 1 1 NCTYPE_VERSION 1 2 diagnostic tools NI resources A 1 documentation conventions used in manual viii how to use manual set vii NI resources A 1 related documentation viii drivers NI resources A 1 National Instruments Corporation E EasyIOClose 2 4 EasylOConfig 2 6 examples NI resources A 1 Explicit Messaging Object 3 2 F functions 2 1 descriptions using 2 1 EasyIOClose 2 4 EasylOConfig 2 6 list of 2 2 ncCloseObject 2 10 ncConvertForDnetWrite 2 12 ncConvertFromDnetRead 2 20 ncCreateNotification 2 27 ncGetDnetAttribute 2 36 ncGetDriverAttr 2 42 ncOpenDnetExpIMsg 2 45 ncOpenDnetIntf 2 48 ncOpenDnetlO 2 54 ncOperateDnetIntf 2 64 ncReadDnetExplMs 2 68 ncReadDnetlIO 2 72 ncSetDnetAttribute 2 75 ncSetDriverAttr 2 80 ncStatusToString 2 83 ncWaitForState 2 86 ncWriteDnetExplMspg 2 91 ncWriteDnetIO 2 95 H help technical support A 1 how to use manual set vii l 1 NI DNET Programmer Reference Manual Index
98. ress of globally declared reference data for use within the notification callback For example for the ReadAvail state RefData is often the data buffer which you pass to ncReadDnetI0 to read available data If the notification callback does not need reference data you can set RefData to NULL Values Pointer to any globally declared data variable or NULL National Instruments Corporation 2 31 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncCreateNotitication Create Notification Callback Description This is the address of a callback function within your application source code Within the code for the callback function you can call any of the NI DNET functions except for ncCreateNotification and ncWaitForState Declare this function using the following C language prototype NCTYPE_STATE _NCFUNC_ Callback NCTYPE_OBJH ObjHandle NCTYPE_STATI CurrentState NCTYPE_STATUS Status NCTYPE_ANY_P RefData Gl In the declaration for your callback the constant _NCFUNC_ is required for your compiler to declare the function such that it can be called by the NI DNET device driver Parameter descriptions for Callback ObjHandle Object handle originally passed to ncCreateNotification This identifies the object generating the notification which is useful when you use the same callback function for multiple objects CurrentState Current state of the object If one of
99. ribute e Execute the DeviceNet Set Attribute Single service on the remote device ncSetDnetAttribute National Instruments Corporation 2 45 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetExpiMsg Open DeviceNet Explicit Messaging e Send any other explicit message request to the remote device and receive the associated explicit message response ncWriteDnetExp1Msg ncReadDnetExplMsg e Configure NI DNET settings that apply to the entire remote device Parameter Descriptions IntfName Description Name of the DeviceNet interface as an ASCII string with format DNETx where x is a decimal number starting at zero that indicates which DeviceNet interface is being used You associate DeviceNet interface names with physical ports using Measurement amp Automation Explorer MAX Values DNETO DNET1 DNET31 In LabVIEW the interface name is selected from an enumerated list The LabWindows CVI function panel also provides an enumerated list DeviceMacld Description MAC ID device address of the remote DeviceNet device Many devices use physical switches to set their MAC ID For such devices you can usually determine the device s MAC ID by examining those switches MAC ID 63 is usually reserved for new devices many devices use 63 as the factory default If you do not know the MAC ID of your DeviceNet device NI DNET provides a utility which can display t
100. riverAttr Get Driver Attribute Purpose Get the value of an attribute in the NI DNET driver Format LabVIEW ObjHandle in ObjHandle out ttriD ttralue Error in Error out C NCTYPE_STATUS ncGetDriverAttr NCTYPE_OBJH ObjHandle NCTYPE_ATTRID Attrid NCTYPE_UINT32 SizeofAttr NCTYPE_ANY P Attr Input ObjHandle Object handle of an open Explicit Messaging Object T O Object or Interface Object Attrid Identifier of the attribute to get SizeofAttr Size of the Attr buffer in bytes C only Output Attr Returned attribute value Function Description ncGetDriverAttr gets the value of an attribute in the NI DNET driver software Within NI DNET objects attributes represent configuration settings status and other information Since you only need to access NI DNET driver attributes under special circumstances ncGetDriverAttr is seldom used For information about the attributes of each NI DNET object refer to Chapter 3 NI DNET Objects ncGetDriverAttr only applies to the NI DNET software on your computer and cannot be used to get an attribute from a remote DeviceNet device To get an attribute from a remote DeviceNet device use the ncGetDnetAttribute function NI DNET Programmer Reference Manual 2 42 ni com Chapter 2 NI DNET Functions ncGetDriverAttr Get Driver Attribute Parameter Descriptions ObjHandle Description ObjHandle must contain an
101. rocess Your application s front panel indicators and controls can only be accessed within the main thread of the LabWindows CVI process Although you can call NI DNET functions and perform generic C calculations in your notification callback you cannot call LabWindows CVI functions which access the front panel the User Interface Library To use the LabWindows CVI User Interface Library save any data needed for front panel indicators using global variables then register a deferred callback using the LabWindows CVI PostDeferredCal1 function Since a LabWindows CVI deferred callback executes in the main thread of the LabWindows CVI process you can call any LabWindows CVI function including the User Interface Library Information Specific to Microsoft Borland and Other C Compilers When the NI DNET device driver calls your notification callback it does so in a separate thread within your process Therefore it has access to any process global data but not thread local data If your callback function needs to access global variables you must protect that access using synchronization primitives such as semaphores because your callback is running in a different thread context For an explanation of these concepts and other multithreading issues refer to the online help of the Microsoft Win32 Software Development Kit SDK National Instruments Corporation 2 33 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions
102. rogrammer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetlO Open DeviceNet 1 0 ExpPacketRate Description Expected rate of I O message packet production in milliseconds As specified in the DeviceNet Specification the expected packet rate is used to trigger data productions The expected packet rate is also used for the watchdog timer to verify that the device on the other side of the T O connection still exists and is producing data as expected The expected packet rate of each I O connection is a major factor in determining the overall performance of your DeviceNet network The following information is specific to the ConnectionType setting and the Pol1Mode setting of your Interface Object Strobe with Automatic poll mode When using the Automatic poll mode the ExpPacketRate setting is ignored for strobed I O Objects The rate of production for the strobe command message is determined automatically by NI DNET Strobe with Scanned or Individual poll mode When using the Scanned or Individual poll mode you must set the ExpPacketRate to the same value for all strobed I O Objects Since a single strobe command message is produced for all strobed T O connections the rate of production for that message must be identical for all strobed I O Objects Poll with Automatic poll mode When using the Automatic poll mode the ExpPacketRate setting is ignored for polled I O Objects NI DNET automatically determ
103. rtFromDnetRead Convert data read from the DeviceNet network into an appropriate LabVIEW data type ncCreateNotification Create a notification callback for an object C only ncGetDnetAttribute Get an attribute value from a DeviceNet device ncGetDriverAttr Get the value of an attribute in the NI DNET driver ncOpenDnetExp1Msg Configure and open an NI DNET Explicit Messaging Object ncReadDnetExp1Msg Read an explicit message response ncSetDnetAttribute Set an attribute value for a DeviceNet device ncSetDriverAttr Set the value of an attribute in the NI DNET driver ncStatusToString Convert status returned from an NI DNET function into a descriptive string C only NI DNET Programmer Reference Manual 3 2 ni com Functions Continued Chapter 3 NI DNET Objects Explicit Messaging Object Function Name Function Description ncWaitForState Wait for one or more states to occur in an object ncWriteDnetExplMsg Write an explicit message request Driver Attributes Current State Attribute ID NC_ATTR_STATE Hex Encoding 80000009 Data Type NCTYPE_STATE Permissions Get Description Current state of the NI DNET object This driver attribute provides the current ReadAvail and Established states as described in the ncWaitForState function Use ncGetDriverAttr when you need to determine the current state of an object but you do n
104. rved Important Information Warranty The media on which you receive National Instruments software are warranted not to fail to execute programming instructions due to defects in materials and workmanship for a period of 90 days from date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace software media that do not execute programming instructions if National Instruments receives notice of such defects during the warranty period National Instruments does not warrant that the operation of the software shall be uninterrupted or error free A Return Material Authorization RMA number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this document is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained i
105. s defined by each operation code Opcode Since none of the operations currently use this additional parameter it is ignored and you should normally set it to zero In the future if new operations require some form of qualifying information this parameter might be used Values 0 NI DNET Programmer Reference Manual 2 66 ni com Chapter 2 NI DNET Functions ncOperateDnetintf Operate DeviceNet Interface Examples LabVIEW Start communication using an Interface Object ObjHandie in ObjiHandie out Error in fH Error out Stop communication for the Interface Object referenced by objh NCTYPE_STATUS status NCTYPE_OBJH objh status ncOperateDnetIntf objh NC_OP_STOP 0 National Instruments Corporation 2 67 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncReadDnetExplMsg Read DeviceNet Explicit Message ncReadDnetExpIMsg Read DeviceNet Explicit Message Purpose Read an explicit message response from an Explicit Messaging Object Format LabVIEW ServiceCode ObjHandle in ObjHandle out ActualServD ataLength Error in ServData Error out C NCTYPE_STATUS ncReadDnetExplMsg NCTYPE_OBJH ObjHandle NCTYPE_UINT8_P ServiceCode NCTYPE_UINT16 SizeofServData NCTYPE_ANY_P ServData NCTYPE_UINT16_P ActualServ DataLength Input ObjHandle Object handle of an open Explicit Messaging Object SizeofServData Size of ServData buffer in bytes C only Output
106. s internal to NI DNET Device ObjHandle In Description Array of I O object handles to be closed You pass in the array returned from Easy IO Config Values The encoding of object handles is internal to NI DNET Examples LabVIEW Close Interface Object and I O Objects opened with Easy IO Config interface ObjHandie in Device ObjiHandie In cocencecocececeoncenceenocenceocr LL Error in National Instruments Corporation 2 5 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions EasylOConfig Easy 10 Contig EasylOConfig Easy 10 Config Purpose Configure and open an NI DNET Interface Object and multiple NI DNET I O Objects Format LabVIEW Interface Name Interface ObjHandle Out Device Configurations Device ObjHandle Out Interface Configuration Error Out C Not applicable Input Interface Name Name of DeviceNet interface Device Configurations Array of I O Object configuration clusters DeviceMacId MAC ID of the remote device ConnectionType Type of I O connection InputLength Number of input bytes OutputLength Number of output bytes ExpPacketRate Expected rate of I O message packet production Interface Configuration Interface Object configuration cluster IntfMacid MAC ID of the DeviceNet interface BaudRate Baud rate PollMode Communication scheme for all polled I O connections Output Interface ObjHandle Out Object handle you use with all subsequent func
107. se is returned in the high byte of DeviceError The Additional Code provides additional information that further describes the error If no additional information is needed the value FF hex is placed into this field The DeviceNet Specification documents values for the General Error Code and Additional Code You can find common error code values in Appendix H DeviceNet Error Codes in the DeviceNet Specification The object description lists object specific error codes Your device s documentation lists vendor specific error codes Values Error codes from the device s error response NI DNET Programmer Reference Manual 2 78 ni com Chapter 2 NI DNET Functions ncSetDnetAttribute Set DeviceNet Attribute Examples LabVIEW Set the Input Range attribute of an Analog Input Object The Input Range is contained in instance 3 of an Analog Input Object class ID 0A hex instance ID 3 attribute ID 7 The DeviceNet data type for Input Range is USINT for which the LabVIEW data type u8 should be used The Timeout is 40 ms 40 ObjHandie in Classld 4J ObjHandie out Instanceld Error in Error out 4ttrD ataLength C Set the MAC ID attribute of a remote DeviceNet device using the Explicit Messaging Object referenced by objh The MAC ID is contained in the DeviceNet Object class ID 3 instance ID 1 attribute ID 1 The DeviceNet data type for Device Type is USINT for which the NI DNET data type
108. specifics of a National Instruments DeviceNet interface Within NI DNET an operating system mechanism that the NI DNET driver uses to communicate events to your application You can think of a notification of as an API function but in the opposite direction See instance Open DeviceNet Vendor s Association Master slave I O connection in which the master sends a poll command to a slave then receives a poll response from that slave A formal set of conventions or rules for the exchange of information among devices of a given network Within NI DNET anything that exists in another device of the device network not on the same host as the NI DNET driver Hardware settings used by National Instruments DeviceNet hardware including an interrupt request level IRQ and an 8 KB physical memory range such as D0000 to D1FFF hex NI DNET Programmer Reference Manual G 4 ni com scanned polling sensor strobed I O V VI Glossary Seconds A polled I O communication scheme in which all poll commands are sent out at the same rate in quick succession A device that measures electrical mechanical or other signals from an external real world variable in the context of device networks sensors are devices that send their primary data value onto the network examples include temperature sensors and presence sensors Also known as transmitter See bit strobed I O Virtual Instrument National Instruments Corpo
109. te is ignored NI DNET Programmer Reference Manual 3 10 ni com Chapter 3 NI DNET Objects 1 0 Object Current State Attribute ID NC_ATTR_ STATE Hex Encoding 80000009 Data Type NCTYPE_STATE Permissions Get Description Current state of the NI DNET object This driver attribute provides the current ReadAvail and Established states as described in ncWaitForState Device Type Attribute ID NC_ATTR_ DEVICE _ TYPE Hex Encoding 80000084 Data Type NCTYPE_UINT16 Permissions Set Description Device Type of the device as reported in the Device Type attribute of device s Identity Object This attribute verifies that the device is the same one expected by your application If the Device Type does not match NI DNET returns the error DnetErrDevInitDevType The Device Type indicates conformance to a specific device profile such as Photoelectric Sensor or Position Controller If you do not callncSetDriverattr to set the Device Type a default value of zero is used When Device Type is zero NI DNET does not verify the device s Device Type Exp Packet Rate Attribute ID NC_ATTR_EXP_PACKET_RATE Hex Encoding 80000095 Data Type NCTYPE_DURATION Permissions Get Description This driver attribute allows you to get the ExpPacketRate originally passed into ncOpenDnet Io National Instruments Corporation 3 11 NI DNET Programmer Reference Manual Chapter
110. tes using DnetData in convert a LabVIEW data type for each data member changed by your LabVIEW program possibly replacing all initial bytes with LabVIEW data then write the bytes onto the DeviceNet network You typically use ncConvertForDnetWrite with the following NI DNET functions e ncWriteDnetlo0 Convert a LabVIEW data type for placement into the output assembly e ncSetDnetAttribute Convert a LabVIEW data type to set as the attribute value e ncWriteDnetExp1Msg Convert a LabVIEW data type for placement into the service request Since DeviceNet data types are similar to C language data types C programming does not need a function like ncConvertForDnetWrite By using standard C language pointer manipulations you can convert an appropriate C language data type for writing as a DeviceNet data member For more information about converting C language data types refer to the Examples at the end of this section Parameter Descriptions DnetData in Description Initial data bytes to write on the DeviceNet network These data bytes are normally created as a constant array of U8 then given valid default values If you need to convert multiple DeviceNet data members you can wire this input terminal from the DnetData out output terminal of a previous use of this function If you replace all initial data bytes using this function the default values are unimportant and you can leave them as zero Values Initial data
111. the notification returns immediately with the appropriate error code For example if you call ncCreateNotification With DesiredState of ReadAvail the notification function will return when data is available for a read or when a DeviceNet communication error such as connection timeout is detected Values A combination of the following bit values 1 hex ReadAvail state constant NC_ST_READ_AVAIL 8 hex Established constant NC_ST_ESTABLISHED In the LabWindows CVI function panel to facilitate combining multiple states you can select a combination from an enumerated list of all valid combinations This list contains the names of each state in the combination such as ReadAvail or Established NI DNET Programmer Reference Manual 2 30 ni com Timeout Chapter 2 NI DNET Functions ncCreateNotitication Create Notification Description Number of milliseconds to wait for one of the desired states If the timeout expires before one of the desired states occurs your notification function is called with CurrentState of 0 and Status of CanErrFunctionTimeout Use the special timeout value of FFFFFFFF hex to wait indefinitely Values 1 to 200000 or FFFFFFFF hex infinite duration constant NC_DURATION_INFINIT OI xw RefData Description RefData provides a pointer that is passed to all calls of your notification callback function It is typically used to provide the add
112. tion calls for the Interface Object Device ObjHandle Out Array of object handles you index to reference a particular I O Object Error out NI DNET Error Cluster output NI DNET Programmer Reference Manual 2 6 ni com Chapter 2 NI DNET Functions EasylOConfig Easy 10 Config Function Description EasylOConfig configures opens and starts an Interface and multiple I O Objects and returns object handles for the newly created objects Internally the EasyIOConfig function makes use of ncOpenDnet Int f ncOpenDnetIoO ncOperateDnetIntf and ncwWaitForState If you are not familiar with the input clusters mentioned above refer to ncOpenDnet Int f and or ncOpenDnet 10 parameter descriptions before reading this section For more details on any of these functions please refer to the corresponding function description given in this chapter Use EasyIOConfig to open multiple devices I O connections with one VI call This high level function accepts Interface Configuration and an array of Device Configurations as its inputs The Device Configurations can contain any number of I O connections that you want to open Remember however that you can only have one instance of a particular connection per device For example you cannot open two poll connections on the same device Similarly opening COS and cyclic connections simultaneously on a device will result in an error since these two connections are mutually exclusive The relationsh
113. tion can convert this DeviceNet data type from an appropriate LabVIEW data type When using C AttrData can point to a variable of the appropriate data type as specified in Chapter 1 NJ DNET Data Types Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from the ncOpenDnetExp1Msg function In LabVIEW Obj Hand1e passes through the VI as an output so that it can be used for subsequent function calls for the object Values The encoding of ObjHand1e is internal to NI DNET Classid Description Identifies the class which contains the attribute You can find descriptions and identifiers for each standard DeviceNet class in the DeviceNet Specification Volume 2 Chapter 6 The DeviceNet Object Library The device vendor documents vendor specific classes Although the DeviceNet Specification allows 16 bit class IDs most class IDs are 8 bit NI DNET automatically used the class ID size 16 bit or 8 bit that is appropriate for your device Values 00 to FFFF hex NI DNET Programmer Reference Manual 2 76 ni com Instanceld Chapter 2 NI DNET Functions ncSetDnetAttribute Set DeviceNet Attribute Description Identifies the instance which contains the attribute Instance ID 0 sets an attribute in the class itself Other instance IDs typically are numbered starting at 1 For example the primary Identity Object in a device uses instance ID 1 Although the DeviceNet
114. to wait for the Established state of an Explicit Messaging Object or else to wait for an explicit message response re ncWriteDnetExp1Msg then read that response using ncReadDnet While waiting for the desired states ncwaitForState suspends the sulting from a call to ExplMsg current execution For C this could suspend your front panel user interface For LabVIEW you can still access your front panel and functions that are not directly connected to ncWaitForState can still NI DNET Programmer Reference Manual 2 86 ni com Chapter 2 NI DNET Functions ncWaitForState Wait For State execute If you want to allow other code in your application to execute while waiting for NI DNET states refer to the ncCreateNotification C only function The functions ncWaitForState and ncCreateNotification use the same underlying implementation Therefore for each object handle only one of these functions can be pending at a time For example you cannot invoke ncWaitForState twice from different threads for the same object For different object handles these functions can overlap in execution The status returned from ncWaitForState indicates any error detected by NI DNET You should always check this return status prior to checking the CurrentState value returned from ncWaitForState Parameter Descriptions ObjHandle Description ObjHandle must contain an object handle returned from ncOpenDnetExp1Msg or ncOpenDnet Io In Lab
115. truments Corporation 2 77 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncSetDnetAttribute Set DeviceNet Attribute AttrData Description Attribute value to set in device The DeviceNet data type in the attribute s description defines the format of the data provided in AttrData When using LabVIEW the ncConvertForDnetWrite function can convert this DeviceNet data type from an appropriate LabVIEW data type When using C AttrData can point to a variable of the appropriate data type as specified in Chapter 1 NI DNET Data Types The AttrDataLength parameter specifies the number of attribute data bytes to set Values Attribute value to set in device DeviceError Description Error codes from device s error response If the remote device responds successfully to the Set Attribute Single service the return status is 0 DnetSuccess and DeviceError returns 0 If the remote device returns an error response for the Set Attribute Single service the return status is BFF62014 hex DnetErrErrorResponse and DeviceError returns the error codes from the response The General Error Code from the device s error response is returned in the low byte of DeviceError Common values for General Error Code include Attribute Not Supported 14 hex Object Does Not Exist 16 hex and Invalid Attribute Value 09 hex The Additional Code from the device s error respon
116. ts LabVIEW data type e ncGetDnetAttribute Convert the attribute to its LabVIEW data type e ncReadDnetExp1Msg Convert a member in the service response to its LabVIEW data type Since DeviceNet data types are similar to C language data types C programming does not need a function like ncConvertFromDnetRead By using standard C language pointer manipulations you can convert a DeviceNet data member into its appropriate C language data type For more information about converting DeviceNet data members into C language data types refer to the Examples at the end of this section Parameter Descriptions DnetData in Description Data bytes read from the DeviceNet network These data bytes are read from the DeviceNet network using ncReadDnet IO ncGetDnetAttribute Or ncReadDnetExp1Msg If you need to convert multiple DeviceNet data members you can wire this input terminal from the DnetData out output terminal of a previous use of this function Values Data output terminal of ncReadDnet IO or AttrData output terminal of ncGetDnetAttribute or ServData output terminal of ncReadDnetExp1Msg or DnetData out output terminal of a previous use of this function National Instruments Corporation 2 21 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncConvertFromDnetRead Convert From DeviceNet Read DnetType Description An enumerated list from which you select the DeviceNet data type to con
117. uments Corporation 2 81 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncSetDriverAttr Set Driver Attribute Examples LabVIEW Verify vendor ID 20 for the DeviceNet device referenced by an Explicit Messaging Object ObjiHandie in ObjiHandie out Device Vendor ID Error in AV alue Error out C Suppress acknowledgments for the COS I O Object referenced by objh NCTYPE_STATUS status NCTYPE_OBJH objh NCTYPE_BOOL ack_sup ack_sup NC_TRUE status ncSetDriverAttr objh NC_ATTR_ACK_SUPPRESS sizeof ack_sup amp ack_sup NI DNET Programmer Reference Manual 2 82 ni com Chapter 2 NI DNET Functions ncStatusToString Status To String ncStatusToString Status To String Purpose Convert status returned from an NI DNET function into a descriptive string Format LabVIEW Not applicable For LabVIEW NI DNET functions use the standard error in and error out clusters for status information You can view error descriptions using built in LabVIEW features such as Explain Error in the Help menu or the Simple Error Handler VI in your diagram void ncStatustoString NCTYPE_STATUS Status NCTYPE_UINT32 SizeofString NCTYPE_STRING String Input Status Status returned from a previous function call SizeofString Size of String buffer in bytes Output String Textual string which describes the function status Function Description For applications written in C C or Visual
118. unicates at a rate which is independent of all other I O connections Change of state COS with any poll mode For COS I O Objects the ExpPacketRate is used solely to verify that the I O connection still exists If no change in data produces T O message within the expected packet rate the previous data is produced again to maintain the I O connection Since this rate is used solely to maintain the I O connection it is often set to a large value such as 10000 10 seconds In addition to the expected packet rate COS I O connections also produce an I O message when a change is detected in the data These I O change messages do not occur at a predetermined rate The time between each I O change message depends on when an actual change takes place and how fast the device can measure new data and detect changes National Instruments Corporation 2 61 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetlO Open DeviceNet 1 0 ExpPacketRate Continued Description Continued Cyclic with any poll mode For cyclic I O Objects the ExpPacketRate determines the rate at which the I O message is produced Each cyclic I O Object communicates at a rate which is independent of all other I O connections Note regarding I O as a slave DeviceMacId equal to Int fMacId The ExpPacketRate Setting applies only to I O Objects used for communication as a master the usual case For I O Objects used for co
119. ure and open an NI DNET Interface Object Open DeviceNet Interface ncOpenDnetIO Configure and open an NI DNET I O Object Open DeviceNet I O ncOperateDnetInt Operate DeviceNet Interface Perform an operation on an NI DNET Interface Object NI DNET Programmer Reference Manual 2 2 ni com Chapter 2 NI DNET Functions List of NI DNET Functions Table 2 1 NI DNET Functions Continued Function Purpose ncReadDnetExp1Msg Read Read an explicit message response from an Explicit DeviceNet Explicit Message Messaging Object ncReadDnetIO Read input from an I O Object Read DeviceNet I O ncSetDnetAttribute Set an attribute value for a DeviceNet device using Set DeviceNet Attribute an Explicit Messaging Object ncSetDriverAttr Set the value of an attribute in the NI DNET driver Set Driver Attribute ncStatusToString Convert status returned from an NI DNET function Status to String into a descriptive string C only ncWaitForState Wait for one or more states to occur in an object Wait for State ncWriteDnetExplMsg Write Write an explicit message request using an Explicit DeviceNet Explicit Message Messaging Object ncWriteDnetIO Write output to an I O Object Write DeviceNet I O National Instruments Corporation 2 3 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions EasylOClose Easy 10 Close EasylOClose Easy 10 Close
120. urpose Set an attribute value for a DeviceNet device using an Explicit Messaging Object Format LabVIEW amp ttrData Timeout ObjHandle in ObjHandle out Classld DeviceError Instanceld Error out Attributeld Error in AttDataLenath C NCTYPE_STATUS ncSetDnetAttribute NCTYPE_OBJH ObjHandle NCTYPE_UINT16 ClassId NCTYPE_UINT16 Instanceld NCTYPE_UINT8 Attributeld NCTYPE_DURATION Timeout NCTYPE_UINT16 AttrDataLength NCTYPE_ANY_P AttrData NCTYPE_UINT16_P DeviceError Input ObjHandle Object handle of an open Explicit Messaging Object ClassId Identifies the class which contains the attribute Instanceld Identifies the instance which contains the attribute Attributeld Identifies the attribute to set Timeout Maximum time to wait for response from device AttrDataLength Number of attribute data bytes to set AttrData Attribute value to set in device Output DeviceError Error codes from device s error response National Instruments Corporation 2 75 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncSetDnetAttribute Set DeviceNet Attribute Function Description ncSetDnetAttribute sets the value of an attribute for a DeviceNet device using an Explicit Messaging Object ncSetDnetAttribute executes the Set Attribute Single service on a remote DeviceNet device The DeviceNet data type in the attribute s description defines the format of the data provided in AttrData When using LabVIEW the ncConvertForDnetWrite func
121. ut DnetData In DnetData Out DnetT ype U32 U16 U8 Out ByteD ffset 1324116418 Out S TF Out DBL SGL Out C Not applicable but see Examples at the end of this section Input DnetData in Data bytes read from the DeviceNet network DnetType DeviceNet data type to convert from ByteOffset Byte offset of the DeviceNet member to convert Output DnetData out DeviceNet data bytes unchanged 8 TF out Converted LabVIEW array of 8 TF 132 116 I8 out Converted LabVIEW 132 116 or 18 U32 U16 U8 out Converted LabVIEW U32 U16 or U8 DBL SGL out Converted LabVIEW DBL or SGL abc out Converted LabVIEW string Function Description Many fundamental differences exist between the encoding of a DeviceNet data type and its equivalent data type in LabVIEW For example for a 32 bit integer the DeviceNet DINT data type uses Intel byte ordering lowest byte first and the equivalent LabVIEW 132 data type uses Motorola byte ordering highest byte first NI DNET Programmer Reference Manual 2 20 ni com Chapter 2 NI DNET Functions ncConvertFromDnetRead Convert From DeviceNet Read ncConvertFromDnetRead takes a sequence of bytes read from the DeviceNet network and given the byte offset and DeviceNet data type for a specific data member in those bytes converts that DeviceNet data member into an appropriate LabVIEW data type You typically use ncConvertFromDnetRead with the following NI DNET functions _ ncReadDnetIO Convert a member of the input assembly to i
122. vert For each DeviceNet data type the list displays the resulting LabVIEW data type in parentheses When you select the DeviceNet data type BOOL ncConvertFromDnetRead converts the byte indicated by ByteOffset into an array of eight LabVIEW Booleans You can index into this array to use specific Boolean members The Boolean at index zero is the least significant bit bit 0 the Boolean at index one is the next least significant bit 1 and so on Values BOOL 8 TF SINT 18 INT 116 DINT 132 USINT U8 UINT U16 UDINT U32 REAL SGL zJ iR AL DBL SHORT_STRING abc STRING abc NI DNET Programmer Reference Manual 2 22 ni com ByteOffset Chapter 2 NI DNET Functions ncConvertFromDnetRead Convert From DeviceNet Read Description Byte offset of the DeviceNet member to convert For the DeviceNet data member you want to convert this is the byte offset in DnetData in where the member begins Byte offsets start at zero You can find information on the format of your DeviceNet data in the following functions ncReadDnet 10 Specification for your device s input assembly ncGetDnetAttribute Data type of the attribute Unless the attribute s DeviceNet data type is a structure or array the value for ByteOffset is always 0 ncReadDnetExp1Msg Specification for the service data of the explicit message response Values 0 to 255
123. work When using Scanned mode since all poll and strobe requests are produced at the same time you normally set the ExpPacketRate for all polled and strobed I O Objects to a common value If you need to isolate devices that are slow to respond to poll requests it is possible to use different ExpPacketRate values while still maintaining the benefits of scanned I O You can set all ExpPacketRate values for polled I O Objects as two groups one foreground group and a second background group whose ExpPacketRate is an exact multiple of the foreground group s All strobed I O must use the same rate as the foreground group for polled I O For example you can set some polled I O and all strobed I O to a common foreground rate of 100 ms and other polled I O to a background rate of 500 ms To maintain overall network determinism the background poll requests are interspersed evenly among each foreground scan National Instruments Corporation 2 51 NI DNET Programmer Reference Manual Chapter 2 NI DNET Functions ncOpenDnetintf Open DeviceNet Interface PollMode Continued Description Continued Individual This mode enables you to configure poll rates individually for each polled I O connection In Individual mode poll requests are not produced as a group but instead each polled I O connection communicates at an independent rate The rate at which each poll request is produced is determined solely by the Exp

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