Home

NI-488.2 User Manual for Windows

1. 5 1 Using the NI Spy Online Help 5 3 Locating Errors with NI Spy 5 3 Viewing Properties for Recorded Calls 5 3 Exiting NI Spy 5 4 Performance Considerations 5 4 Chapter 6 Interactive Control Utility Overview 6 1 Getting Started with Interactive Control 6 1 Interactive Control Syntax 6 5 Number Syntax 6 5 String Syntax 6 6 Address Syntax 6 6 Interactive Control Commands
2. 7 17 Parallel Polling with Traditional NI 488 2 Calls 7 17 Parallel Polling with Multi Device NI 488 2 Calls 7 19 Appendix A GPIB Basics Appendix B Status Word Conditions Appendix C Error Codes and Solutions Appendix D Windows 98 95 Troubleshooting and Common Questions Contents National Instruments Corporation ix NI 488 2 User Manual for Windows Appendix E Windows NT Troubleshooting and Common Questions Appendix F Technical Support Resources Glossary Index Figures Figure 1 1 Linear and Star System Configuration 1 1 Figure 1 2 Example of Multiboard System Configuration 1 2 Figure 2 1 Measurement amp Automation Explorer 2 2 Figure 2 2 Select View Documentation 2 3 Figure 2 3 Select Getting Started Wizard 2 4 Figure 2 4 Select NI 488 2 Troubleshooting Wizard 2 5 Figure 2 5 NI 488 2 Troubleshooting Wizard 2 5 Figure 2 6 Select Scan for Instruments 2 6 Figure 2
3. 6 6 Status Word 6 11 Error Information 6 12 Count Information 6 12 Contents NI 488 2 User Manual for Windows viii National Instruments Corporation Chapter 7 NI 488 2 Programming Techniques Termination of Data Transfers 7 1 High Speed Data Transfers HS488 7 2 Enabling HS488 7 2 System Configuration Effects on HS488 7 3 Waiting for GPIB Conditions 7 4 Asynchronous Event Notification in Win32 NI 488 2 Applications 7 4 Calling the ibnotify Function 7 4 ibnotify Programming Example 7 5 Writing Multithr
4. xi Conventions xii Related Documentation xii Chapter 1 Introduction Setting up and Configuring Your System 1 1 Controlling More Than One Interface 1 2 Configuration Requirements 1 2 Chapter 2 Measurement amp Automation Explorer Overview 2 1 Starting Measurement amp Automation Explorer 2 2 Getting Started with NI 488 2 2 3 Troubleshoot NI 488 2 Problems 2 4 Scan for GPIB Instruments 2 6 Communicate with a GPIB Instrument 2 7 Query Read Write Communication
5. 2 7 Advanced Communication 2 9 About Instrument Communication 2 10 Adding a New GPIB Instrument 2 10 View NI 488 2 Software Version 2 12 Monitor Record and Display NI 488 2 Calls 2 13 View or Change GPIB Interface Settings 2 14 Under Windows 98 95 2 14 Under Windows NT 2 15 View GPIB Instrument Information 2 16 Change GPIB Device Templates 2 17 Under Windows 98 95 2 18 Under Windows NT 2 18 Enable Disable NI 488 2 DOS Support 2 18 U
6. 5 2 Figure 5 2 NI Spy Application 5 3 Contents NI 488 2 User Manual for Windows x National Instruments Corporation Figure 6 1 Select Interactive Control Utility 6 2 Figure A 1 GPIB Address Bits A 2 Tables Table 3 1 Status Word Layout 3 6 Table 6 1 Syntax for Device Level Traditional NI 488 2 Calls in Interactive Control 6 7 Table 6 2 Syntax for Board Level Traditional NI 488 2 Calls in Interactive Control 6 8 Table 6 3 Syntax for Multi Device NI 488 2 Calls in Interactive Control 6 9 Table 6 4 Auxiliary Functions in Interactive Control 6 11 Table A 1 GPIB Handshake Lines A 3 Table A 2 GPIB Interface Management Lines A 3 National Instruments Corporation xi NI 488 2 User Manual for Windows About This Manual This manual describes the features and functions of the
7. EDMA occurs if a system DMA error is encountered when the NI 488 2 software attempts to transfer data over the GPIB using DMA Solutions Possible solutions for this error are as follows You can correct the EDMA problem in the hardware by using the NI 488 2 Configuration utility to reconfigure the hardware to not use a DMA resource You can correct the EDMA problem in the software by using ibdma to disable DMA EOIP 10 EOIP occurs when an asynchronous I O operation has not finished before some other call is made During asynchronous I O you can only use ibstop ibnotify ibwait and ibonl or perform other non GPIB operations If any other call is attempted EOIP is returned Solutions Resynchronize the driver and the application before making any further NI 488 2 calls Resynchronization is accomplished by using one of the following functions ibnotify If the ibsta value passed to the ibnotify callback contains CMPL the driver and application are resynchronized ibwait If the returned ibsta contains CMPL the driver and application are resynchronized ibstop The I O is canceled the driver and application are resynchronized Appendix C Error Codes and Solutions National Instruments Corporation C 7 NI 488 2 User Manual for Windows ibonl The I O is canceled and the interface is reset the driver and application are resynchronized ECAP 11 ECAP results when your GPIB interface lacks the a
8. Possible solutions for this error are as follows Make sure that the GPIB address of your device matches the GPIB address of the device to which you want to write data Use the appropriate hex code in ibcmd to address your device Check your cable connections and make sure at least two thirds of your devices are powered on Call ibpad or ibsad if necessary to match the configured address to the device switch settings Reduce the write byte count to that which is expected by the Controller Appendix C Error Codes and Solutions NI 488 2 User Manual for Windows C 4 National Instruments Corporation EADR 3 EADR occurs when the GPIB interface is CIC and is not properly addressing itself before read and write functions This error is usually associated with board level functions EADR is also returned by the function ibgts when the shadow handshake feature is requested and the GPIB ATN line is already unasserted In this case the shadow handshake is not possible and the error is returned to notify you of that fact Solutions Possible solutions for this error are as follows Make sure that the GPIB interface is addressed correctly before calling ibrd ibwrt RcvRespMsg or SendDataBytes Avoid calling ibgts except immediately after an ibcmd call ibcmd causes ATN to be asserted EARG 4 EARG results when an invalid argument is passed to a function call The following are s
9. table 3 6 description B 2 troubleshooting and common questions See also debugging Interactive Control utility NI Spy utility NI 488 2 problems using Troubleshooting Wizard 2 4 to 2 5 Windows 98 95 D 1 to D 6 common questions D 3 to D 6 Device Manager device status code D 2 to D 3 EDVR error conditions D 1 to D 2 Index National Instruments Corporation I 11 NI 488 2 User Manual for Windows Windows NT E 1 to E 4 common questions E 2 to E 4 examining NT system log using Event Viewer E 2 using diagnostic tools E 1 to E 2 verifying NI 488 2 installation E 1 to E 2 turn OFF display function Interactive Control 6 11 turn ON display function Interactive Control 6 11 V Visual Basic 3 13 to 3 14 Visual C C programming instructions 3 13 W wait function See ibwait function WaitSRQ routine 7 15 Web site support F 1 Windows environment asynchronous event notification in Win32 applications 7 4 to 7 9 calling ibnotify function 7 4 to 7 5 ibnotify programming example 7 5 to 7 9 changing GPIB device templates Windows 98 95 2 18 Windows NT 2 18 enabling disabling NI 488 2 DOS support Windows 98 95 2 18 Windows NT 2 19 GPIB ENET network settings Windows 98 95 2 20 running Win16 NI 488 2 applications under Windows 98 95 3 17 running Win32 applications 3 17 to 3 18 troubleshooting and common questions Windows 98 95 D 1 to D 6 common questions D 3 to D 6 Device Manager devi
10. 7 3 NI 488 2 User Manual for Windows If you are using device level calls the NI 488 2 software automatically sends the HS488 configuration message to devices If you enabled the HS488 protocol in the NI 488 2 Configuration utility the NI 488 2 software sends out the HS488 configuration message when you use ibdev to bring a device online If you call ibconfig to change the GPIB cable length the NI 488 2 software sends out the HS488 message again the next time you call a device level function If you are using board level traditional NI 488 2 calls or multi device NI 488 2 calls and you want to configure devices for high speed you must send the HS488 configuration messages using ibcmd or SendCmds The HS488 configuration message is made up of two GPIB command bytes The first byte the Configure Enable CFE message hex 1F places all HS488 devices into their configuration mode Non HS488 devices should ignore this message The second byte is a GPIB secondary command that indicates the number of meters of cable in your system It is called the Configure CFGn message Because HS488 can operate only with cable lengths of 1 to 15 m only CFGn values of 1 through 15 hex 61 through 6F are valid If the cable length was configured properly in the NI 488 2 Configuration utility you can determine how many meters of cable are in your system by calling ibask option IbaHSCableLength in your application For more information about CFE and CFGn mess
11. CIC See Controller in Charge CIC CIC status word condition bit position hex value and type table 3 7 description B 4 CMPL status word condition bit position hex value and type table 3 7 description B 3 common questions See troubleshooting and common questions communicating with GPIB devices advanced communication 2 9 instrument commands 2 10 multiple GPIB devices 3 10 to 3 13 becoming Controller In Charge 3 11 communicating with devices 3 12 determining GPIB address of device 3 11 to 3 12 general steps and examples 3 11 to 3 13 initialization 3 11 to 3 12 initializing devices 3 12 items to include 3 10 to 3 11 placing device offline 3 13 programming considerations 3 5 query read write communication 2 7 to 2 9 single GPIB device 3 8 to 3 10 clearing devices 3 10 device communication 3 10 general steps and examples 3 9 to 3 10 items to include 3 8 to 3 9 opening devices 3 9 to 3 10 placing device offline 3 10 programming considerations 3 4 to 3 5 using NI 488 2 Communicator 2 7 to 2 10 communication errors 4 5 repeat addressing 4 5 termination method 4 5 configuration 1 1 to 1 3 See also Interactive Control utility errors in configuration 4 4 linear and star system configuration figure 1 1 requirements 1 2 to 1 3 system configuration effects on HS488 7 3 viewing or changing GPIB interface settings 2 14 to 2 16 Windows 98 95 2 14 to 2 15 Windows NT 2 15 to 2 16 Conf
12. In the About Measurement amp Automation Explorer dialog box click on the System Info button 3 Select the Software tab The Name column displays the name of the software The Type column displays operating system information The Value column displays the version number of the software The Description column displays additional information Chapter 2 Measurement amp Automation Explorer National Instruments Corporation 2 13 NI 488 2 User Manual for Windows Monitor Record and Display NI 488 2 Calls To monitor NI 488 2 calls run NI Spy by following these steps 1 Select a GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click and choose NI Spy as shown in Figure 2 12 Figure 2 12 Select NI Spy 2 Start a capture by clicking on the blue arrow on the toolbar of NI Spy 3 Refer to the NI Spy online help for more information To access the NI Spy online help select Help from the NI Spy menu Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 14 National Instruments Corporation View or Change GPIB Interface Settings Under Windows 98 95 To view or change GPIB interface information follow these steps 1 To open the Configuration utility select a GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click a
13. LPCSTR user_iberr Pibcntl long GetProcAddress Gpib32Lib LPCSTR user_ibcnt Pibdev int __stdcall int int int int int int GetProcAddress Gpib32Lib LPCSTR ibdev Pibonl int __stdcall int int GetProcAddress Gpib32Lib LPCSTR ibonl If GetProcAddress fails it returns a NULL pointer The following code fragment shows you how to verify that none of the calls to GetProcAddress failed if Pibsta NULL Piberr NULL Chapter 3 Developing Your NI 488 2 Application National Instruments Corporation 3 17 NI 488 2 User Manual for Windows Pibcntl NULL Pibdev NULL Pibonl NULL Free the GPIB library FreeLibrary Gpib32Lib printf GetProcAddress failed Your Win32 application needs to dereference the pointer to access either the status variables or function The following code shows you how to call a function and access the status variable from within your application dvm Pibdev 0 1 0 T10s 1 0 if Pibsta amp ERR printf Call failed Before exiting your application you need to free gpib 32 dll with the following command FreeLibrary Gpib32Lib For more examples of directly accessing gpib 32 dll refer to the direct entry sample programs dlldevquery c and dll4882query c installed with the NI 488 2 software For more information about direct entry refer to the online help that is built into your development
14. Talker Listener applications 7 11 terminating stuck SRQ state 7 13 waiting for GPIB conditions 7 4 ibwrt function communicating with device example 3 10 using in Interactive Control example 6 4 IFC interface clear line A 3 Interactive Control utility advanced GPIB communication 2 9 auxiliary functions table 6 11 communicating with devices 3 3 3 8 count information 6 12 error information 6 12 getting started 6 1 to 6 5 NI 488 2 call examples 6 2 to 6 5 overview 6 1 programming considerations 3 8 starting 3 3 status word 6 11 syntax 6 5 to 6 6 addresses 6 6 board level calls table 6 8 to 6 9 device level calls table 6 7 to 6 8 multi device NI 488 2 calls table 6 9 to 6 10 numbers 6 5 strings 6 6 Index National Instruments Corporation I 7 NI 488 2 User Manual for Windows interface management lines A 3 interrupts and autopolling 7 13 to 7 14 L LACS status word condition bit position hex value and type table 3 7 description B 5 Talker Listener applications 7 11 to 7 12 languages language specific instructions 3 13 to 3 17 Borland C C 3 13 direct entry with C 3 14 to 3 17 directly accessing gpib 32 dll exports 3 15 to 3 17 gpib 32 dll exports 3 14 to 3 15 Microsoft Visual Basic 3 13 to 3 14 Microsoft Visual C C 3 13 NI 488 2 language interfaces 3 4 listen address setting A 2 Listeners A 1 See also Talker Listener applications LOK status word conditi
15. amp Automation Explorer NI 488 2 User Manual for Windows 2 20 National Instruments Corporation GPIB ENET Network Settings Windows 98 95 Only Assign IP Address Note The Assign IP Address utility requires that you have network administrator knowledge Please contact your network administrator before running this utility 1 In Measurement amp Automation Explorer select a GPIB ENET interface under Devices and Interfaces in the left window frame right click and choose Assign IP Address 2 Use the Assign IP Address utility to assign the IP address Use the online help available in the Assign IP Address utility for more information Configure Advanced IP Settings Note The Advanced IP Settings utility requires that you have network administrator knowledge Please contact your network administrator before running this utility 1 In Measurement amp Automation Explorer select a GPIB ENET interface under Devices and Interfaces in the left window frame right click and choose Advanced IP Settings 2 Use the Advanced IP Settings utility to assign subnet information Use the online help available in the Advanced IP Settings utility for more information Update GPIB ENET Firmware 1 In Measurement amp Automation Explorer select a GPIB ENET interface under Devices and Interfaces in the left window frame right click and choose Update Firmware 2 Use the Update Firmware utility to update firmware
16. 10 National Instruments Corporation FindRQS addrlist Find device asserting SRQ PassControl address Pass control to a device PPoll Parallel poll devices PPollConfig address dataline lineSense Configure device for parallel poll PPollUnconfig addrlist Unconfigure device for parallel poll RcvRespMsg count termination Receive response message ReadStatusByte address Serial poll a device Receive address count termination Receive data from a device ReceiveSetup address Receive setup ResetSys addrlist Reset multiple devices Send address buffer eotmode Send data to a device SendCmds buffer Send command bytes SendDataBytes buffer eotmode Send data bytes SendIFC Send interface clear SendList addrlist buffer eotmode Send data to multiple devices SendLLO Put devices in local lockout SendSetup addrlist Send setup SetRWLS addrlist Put devices in remote with lockout state TestSRQ Test for service request TestSys addrlist Cause multiple devices to perform self tests Trigger address Trigger a device TriggerList addrlist Trigger multiple devices WaitSRQ Wait for service request Table 6 3 Syntax for Multi Device NI 488 2 Calls in Interactive Control Continued Routine Syntax Description Chapter 6 Interactive Control Utility National Instruments Corporation 6 11 NI 488 2 User Manual for Windows Status Word In the Interactive Control utility all NI 488 2 calls except ibfi
17. 2 Troubleshooting Wizard Run the NI 488 2 Troubleshooting Wizard Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB From there select Measurement amp Automation in the left window frame then choose Help Troubleshooting NI 488 2 Troubleshooting Wizard National Instruments Corporation E 1 NI 488 2 User Manual for Windows E Windows NT Troubleshooting and Common Questions This appendix describes how to troubleshoot problems and answers some common questions for Windows NT users Using Windows NT Diagnostic Tools There are many reasons why the NI 488 2 driver might not load If the software is not properly installed or if there is a conflict between the GPIB hardware and the other hardware in the system the NI 488 2 driver fails to start Two Windows NT utilities are useful in determining the source of the problem the Devices applet in the Control Panel and the Event Viewer The following sections describe information available through each utility Examining NT Devices to Verify the Installation To verify whether the devices are installed correctly that is that the devices are started select Start Settings Control Panel and double click on the Devices icon This utility lists all of the devices detected by Windows NT Each device has a status associated with it If the NI 488 2 driver is installed correctly the following lines appear in the list o
18. 4 Debugging Your Application NI Spy 4 1 Global Status Variables 4 2 Existing Applications 4 3 NI 488 2 Error Codes 4 3 Configuration Errors 4 4 Timing Errors 4 4 Communication Errors 4 5 Repeat Addressing 4 5 Termination Method 4 5 Other Errors 4 6 Chapter 5 NI Spy Utility Overview 5 1 Starting NI Spy
19. 488 2 software for Windows NT does not function properly if interrupts are disabled SRQ and Serial Polling with Device Level Traditional NI 488 2 Calls You can use the device level traditional NI 488 2 call ibrsp to conduct a serial poll ibrsp conducts a single serial poll and returns the serial poll response byte to the application If automatic serial polling is enabled the application can use ibwait to suspend program execution until RQS appears in the status word ibsta The program can then call ibrsp to obtain the serial poll response byte The following example shows you how to use the ibwait and ibrsp functions in a typical SRQ servicing situation when automatic serial polling is enabled include decl 32 h char GetSerialPollResponse int DeviceHandle char SerialPollResponse 0 ibwait DeviceHandle TIMO RQS if ibsta amp RQS printf Device asserted SRQ n Use ibrsp to retrieve the serial poll response ibrsp DeviceHandle amp SerialPollResponse return SerialPollResponse Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation 7 15 NI 488 2 User Manual for Windows SRQ and Serial Polling with Multi Device NI 488 2 Calls The NI 488 2 software includes a set of multi device NI 488 2 calls that you can use to conduct SRQ servicing and serial polling Routines pertinent to SRQ servicing and serial polling are AllSpoll ReadStatusByte FindRQS TestSRQ a
20. 5 4 3 2 1 0 Meaning 0 TA LA GPIB Primary Address range 0 30 Appendix A GPIB Basics National Instruments Corporation A 3 NI 488 2 User Manual for Windows Handshake Lines Three hardware handshake lines asynchronously control the transfer of message bytes between devices This process is a three wire interlocked handshake and it guarantees that devices send and receive message bytes on the data lines without transmission error Table A 1 summarizes the GPIB handshake lines Interface Management Lines Five hardware lines manage the flow of information across the bus Table A 2 summarizes the GPIB interface management lines Table A 1 GPIB Handshake Lines Line Description NRFD not ready for data Listening device is ready not ready to receive a message byte Also used by the Talker to signal high speed GPIB transfers NDAC not data accepted Listening device has has not accepted a message byte DAV data valid Talking device indicates signals on data lines are stable valid data Table A 2 GPIB Interface Management Lines Line Description ATN attention Controller drives ATN true when it sends commands and false when it sends data messages IFC interface clear System Controller drives the IFC line to initialize the bus and make itself CIC REN remote enable System Controller drives the REN line to place devices in remote or local program mode SRQ service r
21. 7 Select Communicate with Instrument 2 8 Figure 2 8 NI 488 2 Communicator 2 8 Figure 2 9 Select Interactive Control Utility 2 9 Figure 2 10 Scan for New Instrument After Scanning 2 11 Figure 2 11 Select About Measurement amp Automation Explorer 2 12 Figure 2 12 Select NI Spy 2 13 Figure 2 13 Select Properties 2 14 Figure 2 14 View Interface Information under Windows 98 95 2 15 Figure 2 15 View Interface Information under Windows NT 2 16 Figure 2 16 GPIB Instrument Information 2 17 Figure 3 1 Select Communicate with Instrument 3 2 Figure 3 2 NI 488 2 Communicator 3 2 Figure 4 1 Select NI Spy 4 2 Figure 5 1 Select NI Spy
22. Attention is asserted TACS 3 8 brd Talker LACS 2 4 brd Listener DTAS 1 2 brd Device Trigger State DCAS 0 1 brd Device Clear State Appendix B Status Word Conditions NI 488 2 User Manual for Windows B 2 National Instruments Corporation ERR dev brd ERR is set in the status word following any call that results in an error You can determine the particular error by examining the error variable iberr Appendix C Error Codes and Solutions describes error codes that are recorded in iberr along with possible solutions ERR is cleared following any call that does not result in an error TIMO dev brd TIMO indicates that the timeout period has expired TIMO is set in the status word following any synchronous I O functions for example ibcmd ibrd ibwrt Receive Send and SendCmds if the timeout period expires before the I O operation has completed TIMO is also set in the status word following an ibwait or ibnotify call if the TIMO bit is set in the mask parameter and the timeout period expires before any other specified mask bit condition occurs TIMO is cleared in all other circumstances END dev brd END indicates either that the GPIB EOI line has been asserted or that the EOS byte has been received if the software is configured to terminate a read on an EOS byte If the GPIB interface is performing a shadow handshake as a result of the ibgts function any other function can return a status word w
23. Communicate with Multiple GPIB Devices 3 10 Items to Include 3 10 General Program Steps and Examples 3 11 Language Specific Programming Instructions 3 13 Microsoft Visual C C Version 2 0 or Later 3 13 Borland C C Version 4 0 or Later 3 13 Visual Basic Version 4 0 or Later 3 13 Direct Entry with C 3 14 gpib 32 dll Exports 3 14 Directly Accessing the gpib 32 dll Exports 3 15 Running Existing NI 488 2 Applications 3 17 Running Existing Win32 and Win16 NI 488 2 Applications 3 17 Running Existing DOS NI 488 2 Applications Under Windows 98 95 3 17 Running Existing DOS NI 488 2 Applications under Windows NT 3 18 Contents National Instruments Corporation vii NI 488 2 User Manual for Windows Chapter
24. DIO1 through DIO8 The GPIB lines that are used to transmit command or data bytes from one device to another DLL Dynamic link library DMA Direct memory access High speed data transfer between the GPIB board and memory that is not handled directly by the CPU Not available on some systems See programmed I O driver Device driver software installed within the operating system E END or END Message A message that signals the end of a data string END is sent by asserting the GPIB End or Identify EOI line with the last data byte EOI A GPIB line that signals either the last byte of a data message END or the parallel poll Identify IDY message Glossary National Instruments Corporation G 3 NI 488 2 User Manual for Windows EOS or EOS Byte A 7 or 8 bit end of string character that is sent as the last byte of a data message EOT End of transmission ESB The Event Status bit Part of the IEEE 488 2 defined status byte which is received from a device responding to a serial poll F FIFO First in first out G GET Group Execute Trigger The GPIB command used to trigger a device or internal function of an addressed Listener GPIB General Purpose Interface Bus is the common name for the communications interface system defined in ANSI IEEE Standard 488 1 1987 and ANSI IEEE Standard 488 2 1992 GPIB address The address of a device on the GPIB composed of a primary address MLA and MTA and perhaps a sec
25. GPIB interface as a Listener detects that the Go to Local GTL command has been sent either by the GPIB interface or by another Controller When the ibloc function is called while the LOK bit is cleared in the status word CIC brd CIC indicates whether the GPIB interface is the Controller In Charge CIC is set when the SendIFC routine or ibsic function is executed either while the GPIB interface is System Controller or when another Controller passes control to the GPIB interface CIC is cleared either when the GPIB interface detects Interface Clear IFC from the System Controller or when the GPIB interface passes control to another device ATN brd ATN indicates the state of the GPIB Attention ATN line ATN is set whenever the GPIB ATN line is asserted and it is cleared when the ATN line is unasserted TACS brd TACS indicates whether the GPIB interface is addressed as a Talker TACS is set whenever the GPIB interface detects that its talk address and secondary address if enabled has been sent either by the GPIB interface itself or by another Controller TACS is cleared whenever the GPIB interface detects the Untalk UNT command its own listen address a talk address other than its own talk address or Interface Clear IFC Appendix B Status Word Conditions National Instruments Corporation B 5 NI 488 2 User Manual for Windows LACS brd LACS indicates whether the GPIB interface is addressed as a Listen
26. Interfaces in the left window frame right click and select NI 488 2 Help to view the online help National Instruments Corporation 7 1 NI 488 2 User Manual for Windows 7 NI 488 2 Programming Techniques This chapter describes techniques for using some NI 488 2 calls in your application For more information about each function or routine refer to the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select an interface under Devices and Interfaces in the left window frame right click and select NI 488 2 Help to view the online help Termination of Data Transfers GPIB data transfers are terminated either when the GPIB EOI line is asserted with the last byte of a transfer or when a preconfigured end of string EOS character is transmitted By default EOI is asserted with the last byte of writes and the EOS modes are disabled You can use the ibeot function to enable or disable the end of transmission EOT mode If EOT mode is enabled the GPIB EOI line is asserted when the last byte of a write is sent out on the GPIB If it is disabled the EOI line is not asserted with the last byte of a write You can use the ibeos function to enable disable or configure the EOS modes EOS mode configuration includes the following information A 7 bit or 8 bit EOS byte
27. NI 488 2 software for Windows Overview of the NI 488 2 Documentation All of the NI 488 2 documentation is available on the NI 488 2 for Windows CD The following documents can help you learn about and use the NI 488 2 software and GPIB hardware The Getting Started card briefly describes how to install your NI 488 2 software and GPIB hardware The NI 488 2 User Manual for Windows describes the features and functions of the NI 488 2 software for Windows The NI 488 2 Function Reference Manual for Windows describes the NI 488 2 API The GPIB Hardware Guide contains detailed instructions about how to configure and install your GPIB hardware The hardware guide also includes hardware and software specifications and compliance information You can access each of these documents online by inserting your NI 488 2 for Windows CD and selecting the View Documentation option from the autorun menu You can also view documentation at the National Instruments web site www natinst com manuals The online NI 488 2 Help addresses questions you might have about NI 488 2 and includes troubleshooting information and descriptions of the NI 488 2 API To access the NI 488 2 online help first open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Then expand the Devices and Interfaces item select a GPIB interface right click and select NI 488 2 Help About
28. 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 including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation Trademarks HS488 natinst com NI 488 NI 488 2 and TNT4882 are trademarks of National Instruments Corporation Pr
29. This Manual NI 488 2 User Manual for Windows xii National Instruments Corporation Conventions 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 Bold text denotes items that you must select or click on in the software such as menu items and dialog box options Bold text also denotes parameter names IEEE 488 and IEEE 488 and IEEE 488 2 refer to the ANSI IEEE Standard 488 1 1987 IEEE 488 2 and the ANSI IEEE Standard 488 2 1992 respectively which define the GPIB italic Italic text denotes variables emphasis a cross reference or an introduction to a key concept This font also denotes text that is a placeholder for a word or value that you must supply monospace Text in this font denotes text or characters that you should enter from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk drives paths directories programs subprograms subroutines device names functions operations variables filenames and extensions and code excerpts monospace bold Bold text in this font denotes the messages and responses that the computer au
30. Use the online help available in the Update Firmware utility for more information National Instruments Corporation 3 1 NI 488 2 User Manual for Windows 3 Developing Your NI 488 2 Application This chapter explains how to develop an NI 488 2 application using the NI 488 2 API Simple Instrument Control To establish basic communication with a GPIB instrument using the NI 488 2 Communicator follow these steps 1 Make sure that you have already scanned for instruments as described in the section Scan for GPIB Instruments in Chapter 2 Measurement amp Automation Explorer 2 To start the NI 488 2 Communicator select the GPIB instrument in the right window frame of Measurement amp Automation Explorer right click and choose Communicate with Instrument as shown in Figure 3 1 Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 2 National Instruments Corporation Figure 3 1 Select Communicate with Instrument Figure 3 2 shows the NI 488 2 Communicator application Figure 3 2 NI 488 2 Communicator Chapter 3 Developing Your NI 488 2 Application National Instruments Corporation 3 3 NI 488 2 User Manual for Windows 3 To use the NI 488 2 Communicator choose Query to write a command to the instrument then automatically read a response back choose Write to write a command to the instrument or choose Read to read a response from the instrument Click on the Show S
31. also wait for a device to request service regardless of the state of automatic serial polling by calling ibwait with a mask that contains RQS Do not issue an ibwait call on RQS for a device that does not respond to serial polls Use ibrsp to acquire the serial poll response byte that was received RQS is cleared when all of the stored serial poll response bytes have been reported to you through the ibrsp function CMPL dev brd CMPL indicates the condition of I O operations It is set whenever an I O operation is complete CMPL is cleared while the I O operation is in progress LOK brd LOK indicates whether the interface is in a lockout state While LOK is set the EnableLocal routine or ibloc function is inoperative for that interface LOK is set whenever the GPIB interface detects that the Local Lockout LLO message has been sent either by the GPIB interface or by another Controller LOK is cleared when the System Controller unasserts the Remote Enable REN GPIB line Appendix B Status Word Conditions NI 488 2 User Manual for Windows B 4 National Instruments Corporation REM brd REM indicates whether the interface is in the remote state REM is set whenever the Remote Enable REN GPIB line is asserted and the GPIB interface detects that its listen address has been sent either by the GPIB interface or by another Controller REM is cleared in the following situations When REN becomes unasserted When the
32. asserted A cable problem might exist involving the SRQ line Appendix C Error Codes and Solutions National Instruments Corporation C 9 NI 488 2 User Manual for Windows Although the occurrence of ESRQ warns you of a definite GPIB problem it does not affect GPIB operations except that you cannot depend on the ibsta RQS bit while the condition lasts Solutions Check to see if other devices not used by your application are asserting SRQ Disconnect them from the GPIB if necessary ETAB 20 ETAB occurs only during the FindLstn and FindRQS functions ETAB indicates that there was some problem with a table used by these functions In the case of FindLstn ETAB means that the given table did not have enough room to hold all the addresses of the Listeners found In the case of FindRQS ETAB means that none of the devices in the given table were requesting service Solutions In the case of FindLstn increase the size of result arrays In the case of FindRQS check to see if other devices not used by your application are asserting SRQ Disconnect them from the GPIB if necessary National Instruments Corporation D 1 NI 488 2 User Manual for Windows D Windows 98 95 Troubleshooting and Common Questions This appendix describes how to troubleshoot problems and answers some common questions for Windows 98 95 users Troubleshooting EDVR Error Conditions In some cases NI 488 2 calls may return with
33. correctly Check for loose or faulty cabling or several powered off instruments on the GPIB If the timeout period is too short for the driver to send command bytes increase the timeout period ESTB 15 ESTB is reported only by the ibrsp function ESTB indicates that one or more serial poll status bytes received from automatic serial polls have been discarded because of a lack of storage space Several older status bytes are available however the oldest is being returned by the ibrsp call Solutions Possible solutions for this error are as follows Call ibrsp more frequently to empty the queue Disable autopolling with the ibconfig function option IbcAUTOPOLL or the NI 488 2 Configuration utility To start the NI 488 2 Configuration utility select Start Programs National Instruments NI 488 2 Explore GPIB Select a GPIB interface under Devices and Interfaces in the left window frame right click and choose Properties ESRQ 16 ESRQ can only be returned by a device level ibwait call with RQS set in the mask ESRQ indicates that a wait for RQS is not possible because the GPIB SRQ line is stuck on This situation can be caused by the following events Usually a device unknown to the software is asserting SRQ Because the software does not know of this device it can never serial poll the device and unassert SRQ A GPIB bus tester or similar equipment might be forcing the SRQ line to be
34. determine which version of the NI 488 2 software I have installed Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Select Measurement amp Automation in the left window frame then choose Help About Measurement amp Automation Explorer In the About Measurement amp Automation Explorer dialog box click on the System Info button Then select the Software tab The Name Type Value and Description columns appear describing the NI 488 2 software attributes How many GPIB interfaces can I configure for use with my NI 488 2 software You can configure the NI 488 2 software to communicate with up to four GPIB interfaces How many devices can I configure for use with my NI 488 2 software The NI 488 2 software provides a total of 100 logical devices for applications to use The default number of devices is 32 Are interrupts and DMA required with the NI 488 2 software Interrupts are required but DMA is not How can I determine if my GPIB hardware and NI 488 2 software are installed properly Run the NI 488 2 Troubleshooting Wizard to make sure that your hardware and software are correctly installed Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB From there select Measurement amp Automation in the left window frame then choose Help Troubleshooting NI 488 2 Troubleshooting Wizard
35. expected response then the device has valid data to send otherwise it has a fault condition to report if SpollByte expectedResponse printf Device returned invalid response Status byte 0x x n SpollByte DeviceError TRUE return 0 Read the data from the device If the ERR bit is set in ibsta then print an error message and return LocalIbsta ibrd LocalUd ReadBuffer 40L if LocalIbsta amp ERR printf ibrd failed No more callbacks n DeviceError TRUE return 0 The string returned by ibrd is a binary string whose length is specified by the byte count in ibcntl However many GPIB instruments return ASCII data strings and this example makes this assumption Because of this it is possible to add a NULL character to the end of the data received and use the printf function to display the ASCII data The following code illustrates that ReadBuffer ibcntl 0 Convert the data into a numeric value sscanf ReadBuffer f amp Readings ReadingsTaken Display the data printf Reading f n Readings ReadingsTaken ReadingsTaken 1 if ReadingsTaken gt 1000 return 0 else Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation 7 9 NI 488 2 User Manual for Windows Issue a request to the device to send the data and rearm callback on RQS LocalIbsta ibwrt LocalUd SEND DATA 9L
36. require customized configuration of the NI 488 2 driver For example you might want to terminate reads on a special end of string character or you might require secondary addressing In these cases you can either reconfigure from your application using the ibconfig function or reconfigure using the NI 488 2 Configuration utility Note National Instruments recommends using ibconfig to modify the configuration If your application uses ibconfig it works properly regardless of the previous configuration For more information about using ibconfig refer to the description of ibconfig in the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces in the left window frame right click and choose NI 488 2 Help to view the online help Timing Errors If your application fails but the same calls issued interactively in the Interactive Control utility are successful your program might be issuing the NI 488 2 calls too quickly for your device to process and respond to them This problem can also result in corrupted or incomplete data This should only be a problem with older non standard GPIB devices To check if your interactively issued NI 488 2 calls succeed use the Interactive Control utility To start the Interactive Control utility select a G
37. sequences you use are dependent on the specific instrument The documentation for each instrument should include the GPIB commands you need to communicate with it In most cases device level traditional NI 488 2 calls are sufficient for communicating with instruments For more information refer to Chapter 3 Developing Your NI 488 2 Application How can I easily start communicating with my GPIB instrument Use the NI 488 2 Communicator for simple instrument communication To start the NI 488 2 Communicator select Start Programs National Instruments NI 488 2 Explore GPIB From there right click on the GPIB instrument in the right window frame Then choose Communicate With Instrument For more information about communicating with your GPIB instrument refer to the section Communicate with a GPIB Instrument in Chapter 2 Measurement amp Automation Explorer Appendix D Windows 98 95 Troubleshooting and Common Questions NI 488 2 User Manual for Windows D 6 National Instruments Corporation What can I do to check for errors in my NI 488 2 application Examine the value of ibsta after each NI 488 2 call If a call fails the ERR bit of ibsta is set and an error code is stored in iberr For more information about global status variables refer to Chapter 4 Debugging Your Application What information should I have before I call National Instruments When you call National Instruments you should have the results of the NI 488
38. the ERR bit set in ibsta and the value EDVR in iberr The value stored in ibcntl is useful in troubleshooting the error condition EDVR Error Condition with ibcntl Set to 0xE028002C 534249428 If a call is made with an interface number that is within the range of allowed interface numbers typically 0 to 3 but which has not been assigned to a GPIB interface an EDVR error condition occurs with ibcntl set to 0xE028002C You can assign an interface number to a GPIB interface by configuring the NI 488 2 software and selecting an interface name For information about how to configure the NI 488 2 software refer to the online help in the NI 488 2 Configuration utility To start the NI 488 2 Configuration utility open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Select a GPIB interface under Devices and Interfaces in the left window frame right click and choose Properties EDVR Error Condition with ibcntl Set to 0xE0140025 535560155 If a call is made with an interface number that is not within the range of allowed interface numbers typically 0 to 3 an EDVR error condition occurs with ibcntl set to 0xE0140025 Appendix D Windows 98 95 Troubleshooting and Common Questions NI 488 2 User Manual for Windows D 2 National Instruments Corporation EDVR Error Condition with ibcntl Set to 0xE0140035 535560139 If a call is made with a device name that is not
39. the device file for one or more of the devices that make up the NI 488 2 driver and an event is logged that The system cannot find the file specified In this case the NI 488 2 software is not installed properly You should reinstall the NI 488 2 software from the NI 488 2 for Windows CD A conflict exists between the GPIB hardware and the other hardware in the system If this is the case an event is logged that indicates the nature of the resource conflict To correct this conflict run the Troubleshooting Wizard and follow its instructions for resolving resource conflicts To run the Troubleshooting Wizard first open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB From there select Measurement amp Automation in the left window frame then choose Help Troubleshooting NI 488 2 Troubleshooting Wizard Common Questions How can I determine which type of GPIB hardware I have installed Run the NI 488 2 Troubleshooting Wizard It lists all the known GPIB hardware Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB From there select Measurement amp Automation in the left window frame then choose Help Troubleshooting NI 488 2 Troubleshooting Wizard Appendix E Windows NT Troubleshooting and Common Questions National Instruments Corporation E 3 NI 488 2 User Manual for Windows How can I
40. the interface is not CIC Any device level traditional NI 488 2 calls that affect the GPIB Any board level traditional NI 488 2 calls that issue GPIB command bytes ibcmd ibcmda ibln and ibrpp Appendix C Error Codes and Solutions National Instruments Corporation C 3 NI 488 2 User Manual for Windows ibcac and ibgts Any NI 488 2 multi device calls that issue GPIB command bytes SendCmds PPoll Send and Receive Solutions Possible solutions for this error are as follows Use ibsic or SendIFC to make the GPIB interface become CIC on the GPIB Use ibrsc 1 to make sure your GPIB interface is configured as System Controller In multiple CIC situations always be certain that the CIC bit appears in the status word ibsta before attempting these calls If it does not appear you can perform an ibwait for CIC call to delay further processing until control is passed to the interface ENOL 2 ENOL usually occurs when a write operation is attempted with no Listeners addressed For a device write ENOL indicates that the GPIB address configured for that device in the software does not match the GPIB address of any device connected to the bus that the GPIB cable is not connected to the device or that the device is not powered on ENOL can occur in situations where the GPIB interface is not the CIC and the Controller asserts ATN before the write call in progress has ended Solutions
41. threads of execution You can avoid this problem in two ways Use synchronization to protect access to process global variables Do not use process global variables Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 10 National Instruments Corporation If you choose to implement the synchronization solution you must ensure that the code making NI 488 2 calls and examining the NI 488 2 globals modified by a NI 488 2 call is protected by a synchronization primitive For example each thread might acquire a semaphore before making a NI 488 2 call and then release the semaphore after examining the NI 488 2 globals modified by the call For more information about the use of synchronization primitives refer to the documentation about using Win32 synchronization objects that came with your development tools If you choose not to use process global variables you can access per thread copies of the NI 488 2 global variables using a special set of NI 488 2 calls Whenever a thread makes a NI 488 2 call the driver keeps a private copy of the NI 488 2 globals for that thread The driver keeps a separate private copy for each thread The following code shows the set of functions you can use to access these per thread NI 488 2 global variables int ThreadIbsta return thread specific ibsta int ThreadIberr return thread specific iberr int ThreadIbcnt return thread specific ibcnt long Thre
42. utility prompts you for parameters Chapter 6 Interactive Control Utility National Instruments Corporation 6 7 NI 488 2 User Manual for Windows Table 6 1 Syntax for Device Level Traditional NI 488 2 Calls in Interactive Control Syntax Description ibask option Return configuration information where option is a mnemonic for a configuration parameter ibbna bname Change access interface of device where bname is symbolic name of new interface ibclr Clear specified device ibconfig option value Alter configurable parameters where option is mnemonic for a configuration parameter ibdev BdIndx pad sad tmo eot eos Open an unused device ibdev parameters are BdIndx pad sad tmo eot eos ibeos v Change disable EOS message ibeot v Enable disable END message ibln pad sad Check for presence of device on the GPIB at pad sad ibloc Go to local ibonl v Place device online or offline ibpad v Change primary address ibpct Pass control ibppc v Parallel poll configure ibrd count Read data where count is the bytes to read ibrda count Read data asynchronously where count is the bytes to read ibrdf flname Read data to file where flname is pathname of file to read ibrpp Conduct a parallel poll ibrsp Return serial poll byte ibsad v Change secondary address ibstop Abort asynchronous operation ibtmo v Change disable time limit ibtrg Trigger selected device Chapter 6 Interactive Control U
43. window frame Note If the message Instruments not Found appears in the right window frame Scan for Instruments failed because it did not find any instruments Make sure that your GPIB instruments are properly connected to the GPIB interface with a GPIB cable and that they are powered on then repeat the Scan for Instruments Chapter 2 Measurement amp Automation Explorer National Instruments Corporation 2 7 NI 488 2 User Manual for Windows Note If the message Instruments Enumeration Failed appears in the right window frame Scan for Instruments found too many Listeners on the GPIB You might encounter this message if you have a running GPIB Analyzer with the GPIB handshake option enabled To fix this problem disable the GPIB handshake option in the GPIB Analyzer You might also encounter this message if you have a GPIB extender in your system In this case Scan for Instruments cannot detect any instruments connected to your GPIB interface You can verify communication with the instruments using the Interactive Control utility To view the Interactive Control utility help on verifying instrument communication select the GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click and choose Interactive Control Then type help Interactive Control getting started Communicate with a GPIB Instrument Query Read Write Communication To establish basic communication with
44. you how to use FindRQS to find the first device that is requesting service void GetASerialPollResponse char DevicePad char DeviceResponse char SerialPollResponse 0 int WaitResult Addr4882_t Addrlist 4 3 4 5 NOADDR WaitSRQ 0 amp WaitResult Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 16 National Instruments Corporation if WaitResult printf SRQ is asserted n FindRQS 0 AddrList amp SerialPollResponse if ibsta amp ERR printf Device at pad x returned byte x n AddrList ibcnt int SerialPollResponse DevicePad AddrList ibcnt DeviceResponse SerialPollResponse return Example 2 Using AllSpoll This example shows you how to use AllSpoll to serial poll three devices with a single call void GetAllSerialPollResponses Addr4882_t AddrList short ResponseList int WaitResult WaitSRQ 0 amp WaitResult if WaitResult printf SRQ is asserted n AllSpoll 0 AddrList ResponseList if ibsta amp ERR for i 0 AddrList i NOADDR i printf Device at pad x returned byte x n AddrList i ResponseList i return Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation 7 17 NI 488 2 User Manual for Windows Parallel Polling Although parallel polling is not widely used it is a useful method for obtaining the status of more than one
45. 0 3 5 1 2 Conduct the parallel poll using PPoll store the response and check the response for a certain value In the following example because DIO5 is asserted by the device if ist is 1 the program checks bit 4 hex 10 in the response to determine the value of ist PPoll 0 amp response If response has bit 4 hex 10 set the ist bit of the device at that time is equal to 1 If it does not appear the ist bit is equal to 0 Check the bit in the following statement if response amp 0x10 printf The ist equals 1 n else printf The ist equals 0 n 3 Unconfigure the device for parallel polling using PPollUnconfig as shown in the following example In this example the NOADDR constant must appear at the end of the array to signal the end of the address list If NOADDR is the only value in the array all devices receive the parallel poll disable message AddressList 0 3 AddressList 1 NOADDR PPollUnconfig 0 AddressList National Instruments Corporation A 1 NI 488 2 User Manual for Windows A GPIB Basics The ANSI IEEE Standard 488 1 1987 also known as General Purpose Interface Bus GPIB describes a standard interface for communication between instruments and controllers from various vendors It contains information about electrical mechanical and functional specifications GPIB is a digital 8 bit parallel communications interface with data transfer rates of 1 Mbyte s and h
46. 3 6 to 3 7 writing multithreaded Win32 NI 488 2 applications 7 9 to 7 10 GPIB configuration 1 1 to 1 3 controlling more than one interface 1 2 linear and star system configuration figure 1 1 requirements 1 2 to 1 3 definition A 1 overview A 1 resources on National Instruments GPIB Web site 2 19 sending messages across A 2 to A 3 data lines A 2 handshake lines A 3 interface management lines A 3 Talkers Listeners and Controllers A 1 viewing or changing interface settings 2 14 to 2 16 Windows 98 95 2 14 to 2 15 Windows NT 2 15 to 2 16 GPIB addresses address bit configuration figure A 2 listen address A 2 primary A 2 purpose A 2 repeat addressing 4 5 secondary A 2 syntax in Interactive Control 6 6 talk address A 2 GPIB instruments adding new 2 10 to 2 11 changing device templates 2 17 to 2 18 Windows 98 95 2 18 Windows NT 2 18 communicating with See communicating with GPIB devices multiple See multiple interfaces or multiple GPIB devices scanning for 2 6 to 2 7 viewing information 2 16 to 2 17 gpib 32 dll exports accessing directly 3 15 to 3 17 direct entry with C 3 14 to 3 15 GPIB ENET network settings Windows 98 95 assigning IP address 2 20 configuring advanced IP settings 2 20 updating GPIB ENET firmware 2 20 H handshake lines A 3 help accessing additional help resources National Instruments GPIB Web site 2 19 NI 488 2 online help 2 19 NI Spy help 5 3 help displ
47. 8 2 call if ibsta amp ERR printf NI 488 2 error d encountered iberr Note The value in iberr is meaningful as an error type only when the ERR bit is set in ibsta indicating that an error has occurred SRQI 12 1000 brd SRQ interrupt received RQS 11 800 dev Device requesting service CMPL 8 100 dev brd I O completed LOK 7 80 brd Lockout State REM 6 40 brd Remote State CIC 5 20 brd Controller In Charge ATN 4 10 brd Attention is asserted TACS 3 8 brd Talker LACS 2 4 brd Listener DTAS 1 2 brd Device Trigger State DCAS 0 1 brd Device Clear State Table 3 1 Status Word Layout Continued Mnemonic Bit Pos Hex Value Type Description Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 8 National Instruments Corporation For more information about error codes and solutions refer to Chapter 4 Debugging Your Application or Appendix C Error Codes and Solutions Count Variables ibcnt and ibcntl The count variables are updated after each read write or command function In Win32 applications ibcnt and ibcntl are 32 bit integers On some systems like MS DOS ibcnt is a 16 bit integer and ibcntl is a 32 bit integer For cross platform compatibility all applications should use ibcntl If you are reading data the count variables indicate the number of bytes read If you are sending data or commands the count variab
48. Chapter 6 Interactive Control Utility NI 488 2 User Manual for Windows 6 12 National Instruments Corporation Error Information If an NI 488 2 call completes with an error the Interactive Control utility displays the relevant error mnemonic In the following example an error condition EBUS has occurred during a data transfer ud0 ibwrt IDN 8100 err cmpl error EBUS count 1 ud0 In this example the addressing command bytes could not be transmitted to the device This indicates that either the GPIB device is powered off or the GPIB cable is disconnected For a detailed list of the error codes and their meanings refer to Chapter 4 Debugging Your Application Count Information When an I O function completes the Interactive Control utility displays the actual number of bytes sent or received regardless of the existence of an error condition If one of the addresses in an address list is invalid then the error is EARG and the Interactive Control utility displays the index of the invalid address as the count The count has a different meaning depending on which NI 488 2 call is made For the correct interpretation of the count return refer to the function descriptions in the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select an interface under Devices and
49. Charge applications you can also use the NI 488 2 software in most non Controller situations These situations are known as Talker Listener applications because the interface is not the GPIB Controller A Talker Listener application typically uses ibwait with a mask of 0 to monitor the status of the interface Then based on the status bits set in ibsta the application takes whatever action is appropriate For example Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 12 National Instruments Corporation the application could monitor the status bits TACS Talker Active State and LACS Listener Active State to determine when to send data to or receive data from the Controller The application could also monitor the DCAS Device Clear Active State and DTAS Device Trigger Active State bits to determine if the Controller has sent the device clear DCL or SDC or trigger GET messages to the interface If the application detects a device clear from the Controller it might reset the internal state of message buffers If it detects a trigger message from the Controller the application might begin an operation such as taking a voltage reading if the application is actually acting as a voltmeter Serial Polling You can use serial polling to obtain specific information from GPIB devices when they request service When the GPIB SRQ line is asserted it signals the Controller that a service request is pending T
50. E Institute of Electrical and Electronic Engineers interface message A broadcast message sent from the Controller to all devices and used to manage the GPIB I O Input Output In this manual it is the transmission of commands or messages between the system via the GPIB board and other devices on the GPIB I O address The address of the GPIB board from the point of view of the CPU as opposed to the GPIB address of the GPIB board Also called port address or board address ISA Industry Standard Architecture ist An Individual Status bit of the status byte used in the Parallel Poll Configure function K KB Kilobytes Glossary National Instruments Corporation G 5 NI 488 2 User Manual for Windows L LAD Listen address See MLA language interface Code that enables an application program that uses NI 488 functions or NI 488 2 routines to access the driver Listener A GPIB device that receives data messages from a Talker LLO Local Lockout The GPIB command used to tell all devices that they may or should ignore remote GPIB data messages or local front panel controls depending on whether the device is in local or remote program mode low level function A rudimentary board or device function that performs a single operation M m Meters MAV The Message Available bit is part of the IEEE 488 2 defined status byte which is received from a device responding to a serial poll MB Megabytes me
51. EOS comparison method This indicates whether the EOS byte has seven or eight significant bits For a 7 bit EOS byte the eighth bit of the EOS byte is ignored EOS write method If this is enabled the GPIB EOI line is automatically asserted when the EOS byte is written to the GPIB If the buffer passed into an ibwrt call contains five occurrences of the EOS byte the EOI line is asserted as each of the five EOS bytes are written to the GPIB If an ibwrt buffer does not contain an occurrence of the Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 2 National Instruments Corporation EOS byte the EOI line is not asserted unless the EOT mode is enabled in which case the EOI line is asserted with the last byte of the write EOS read method If this is enabled ibrd ibrda and ibrdf calls are terminated when the EOS byte is detected on the GPIB when the GPIB EOI line is asserted or when the specified count is reached If the EOS read method is disabled ibrd ibrda and ibrdf calls terminate only when the GPIB EOI line is asserted or the specified count has been read You can use the ibconfig function to configure the software to indicate whether the GPIB EOI line was asserted when the EOS byte was read in Use the IbcEndBitIsNormal option to configure the software to report only the END bit in ibsta when the GPIB EOI line is asserted By default END is reported in ibsta when either the EOS b
52. GPIB cable and that they are powered on then repeat the Scan for Instruments Note If the message Instruments Enumeration Failed appears in the right window frame Scan for Instruments found too many Listeners on the GPIB You might encounter this message if you have a running GPIB Analyzer with the GPIB handshake option enabled To fix this problem disable the GPIB handshake option in the GPIB Analyzer You might also encounter this message if you have a GPIB extender in your system In this case Scan for Instruments cannot detect any instruments connected to your GPIB interface You can verify communication with the instruments using the Interactive Control utility To view the Interactive Control utility help on verifying instrument communication select the GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click and choose Interactive Control Then type help Interactive Control getting started Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 12 National Instruments Corporation View NI 488 2 Software Version To view the NI 488 2 software version follow these steps 1 Select Measurement amp Automation in the left window frame of Measurement amp Automation Explorer then choose Help About Measurement amp Automation Explorer as shown in Figure 2 11 Figure 2 11 Select About Measurement amp Automation Explorer 2
53. I 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces right click and choose NI 488 2 Help to view the online help The functions ibbna ibfind ibrdf and ibwrtf all require an argument that is a name ibbna requires an interface name ibfind requires an interface or device name and ibrdf and ibwrtf require a file name Because Windows NT supports both normal 8 bit and Unicode 16 bit characters gpib 32 dll exports both normal and Unicode versions of these functions Because Windows 98 95 does not support 16 bit wide characters use only the 8 bit ASCII versions named ibbnaA ibfindA ibrdfA and ibwrtfA The Unicode versions are named ibbnaW ibfindW ibrdfW and ibwrtfW You can use either the Unicode or ASCII versions of these functions with Windows NT but only the ASCII versions with Windows 98 95 In addition to pointers to the status variables and a handle to the loaded gpib 32 dll you must define the direct entry prototypes for the functions you use in your application The prototypes for each function Chapter 3 Developing Your NI 488 2 Application National Instruments Corporation 3 15 NI 488 2 User Manual for Windows exported by gpib 32 dll are described in the NI 488 2 online help The direct entry sample programs illust
54. Measurement amp Automation Explorer In the About Measurement amp Automation Explorer dialog box click on the System Info button Then select the Software tab The Name Type Value and Description columns appear describing the NI 488 2 software attributes How do I get started Use the NI 488 2 Getting Started Wizard to get started with the NI 488 2 software Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB select Measurement amp Automation in the left window frame then choose Help Getting Started NI 488 2 Getting Started Wizard and follow the instructions How do I troubleshoot problems Run the NI 488 2 Troubleshooting Wizard Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB From there select Measurement amp Automation in the left window frame then choose Help Troubleshooting NI 488 2 Troubleshooting Wizard How many GPIB interfaces can I configure for use with my NI 488 2 software You can configure the NI 488 2 software to communicate with up to 100 GPIB interfaces How many devices can I configure for use with my NI 488 2 software The NI 488 2 software provides a total of 1 024 logical devices for applications to use The default number of devices is 32 The maximum number of physical devices you should connect to a single GPIB interface is 14 or fewer depending on your s
55. NI 488 2 NI 488 2 User Manual for Windows NI 488 2 User Manual for Windows February 1999 Edition Part Number 321819C 01 Worldwide Technical Support and Product Information http www natinst com National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin Texas 78759 3504 USA Tel 512 794 0100 Worldwide Offices Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 284 5011 Canada Ontario 905 785 0085 Canada Qu bec 514 694 8521 Denmark 45 76 26 00 Finland 09 725 725 11 France 0 1 48 14 24 24 Germany 089 741 31 30 Hong Kong 2645 3186 India 91805275406 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico D F 5 280 7625 Mexico Monterrey 8 357 7695 Netherlands 0348 433466 Norway 32 84 84 00 Singapore 2265886 Spain Madrid 91 640 0085 Spain Barcelona 93 582 0251 Sweden 08 587 895 00 Switzerland 056 200 51 51 Taiwan 02 2377 1200 United Kingdom 01635 523545 For further support information see the Technical Support Resources appendix of this manual Copyright 1998 1999 National Instruments Corporation All rights reserved Important Information Warranty The media on which you receive National Instruments software are warranted not to fail to execute programming instructions due to defects in materials and workmanship for a period of 90 days from date of shipment as evidenced by receipts or other documentation
56. NI 488 2 calls table 6 8 to 6 9 device level traditional NI 488 2 calls table 6 7 to 6 8 examples 6 2 to 6 5 multi device NI 488 2 calls table 6 9 to 6 10 language interfaces 3 4 low level functions 3 5 monitoring recording and displaying calls 2 13 multiple interfaces and or multiple devices 3 5 overview 3 4 parallel polling 7 17 to 7 19 implementing 7 17 to 7 19 using multi device NI 488 2 calls 7 19 using traditional NI 488 2 calls 7 17 to 7 18 serial polling 7 12 to 7 16 automatic serial polling 7 13 to 7 14 autopolling and interrupts 7 13 to 7 14 stuck SRQ state 7 13 Index National Instruments Corporation I 9 NI 488 2 User Manual for Windows service requests from IEEE 488 devices 7 12 from IEEE 488 2 devices 7 12 SRQ and serial polling AllSpoll example 7 16 with device level traditional NI 488 2 calls 7 14 FindRQS example 7 15 to 7 16 with multi device NI 488 2 calls 7 15 to 7 16 Talker Listener applications 7 11 to 7 12 termination of data transfers 7 1 to 7 2 troubleshooting See troubleshooting and common questions viewing software version 2 12 waiting for GPIB conditions 7 4 writing multithreaded Win32 NI 488 2 applications 7 9 to 7 10 NI 488 2 Communicator query read write communication 2 7 to 2 9 simple instrument control 3 1 to 3 3 NI 488 2 driver choosing access method 3 3 to 3 4 direct entry access 3 4 NRFD not ready for data line table A 3 number s
57. 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 in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO
58. O is not progressing the Listener is not continuing to handshake or the Talker has stopped talking or the byte count in the call which timed out was more than the other device was expecting Solutions Possible solutions for this error are as follows Use the correct byte count in input functions or have the Talker use the END message to signify the end of the transfer Lengthen the timeout period for the I O operation using ibtmo Make sure that you have configured your device to send data before you request data ENEB 7 ENEB occurs when no GPIB interface exists at the I O address specified in the configuration program This problem happens when the interface is not physically plugged into the system the I O address specified during configuration does not match the actual interface setting or there is a system conflict with the base I O address Solutions Make sure there is a GPIB interface in your computer that is properly configured both in hardware and software using a valid base I O address by running the NI 488 2 Troubleshooting Wizard To run the NI 488 2 Appendix C Error Codes and Solutions NI 488 2 User Manual for Windows C 6 National Instruments Corporation Troubleshooting Wizard select Start Programs National Instruments NI 488 2 Explore GPIB Then select Measurement amp Automation in the left window frame and choose Help Troubleshooting NI 488 2 Troubleshooting Wizard EDMA 8
59. PIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click and choose Interactive Control A well behaved IEEE 488 device does not experience timing errors If your device is not well behaved you can test for and resolve the timing error by single stepping through your program and inserting finite delays between each NI 488 2 call One way to do this is to have your device communicate its status whenever possible Although this method is not possible with many devices it is usually the best option Your delays are controlled by the device and your application can adjust itself and work independently on any platform Other delay mechanisms probably exhibit differing behaviors on different platforms and thus might not eliminate timing errors Chapter 4 Debugging Your Application National Instruments Corporation 4 5 NI 488 2 User Manual for Windows Communication Errors The following sections describe communication errors you might encounter in your application Repeat Addressing Devices adhering to the IEEE 488 2 standard should remain in their current state until specific commands are sent across the GPIB to change their state However some devices require GPIB addressing before any GPIB activity Therefore you might need to configure your NI 488 2 driver to perform repeat addressing if your device does not remain in its currently addressed state You can either reconf
60. Q and serial polling with device level traditional NI 488 2 calls 7 14 with multi device NI 488 2 calls 7 15 to 7 16 set 488 2 v function Interactive Control utility 6 11 set udname function Interactive Control utility 6 11 setting up your system See configuration single GPIB device communicating with See communicating with GPIB devices SRQ service request line automatic serial polling 7 13 to 7 14 purpose table A 3 stuck SRQ state 7 13 SRQI status word condition bit position hex value and type table 3 7 description B 3 status word ibsta 3 6 to 3 7 ATN B 4 CIC B 4 CMPL B 3 DCAS 7 12 B 5 DTAS 7 12 B 5 END B 2 ERR B 2 Interactive Control example 6 11 LACS 7 12 B 5 LOK B 3 programming considerations 3 6 to 3 7 REM B 4 RQS B 3 SRQI B 3 status word layout table 3 6 to 3 7 B 1 TACS 7 12 B 4 TIMO B 2 string syntax in Interactive Control 6 6 stuck SRQ state 7 13 System Controller as Controller in Charge A 1 T TACS status word condition bit position hex value and type table 3 7 description B 4 Talker Listener applications 7 12 talk address setting A 2 Talker Listener applications 7 11 to 7 12 Talkers A 1 technical support resources F 1 to F 2 telephone and fax support F 2 termination methods errors caused by 4 5 termination of data transfers 7 1 to 7 2 TestSRQ routine 7 15 timing errors 4 4 TIMO status word condition bit position hex value and type
61. Utility National Instruments Corporation 6 9 NI 488 2 User Manual for Windows ibppc v Parallel poll configure ibrd count Read data where count is the bytes to read ibrda count Read data asynchronously where count is the bytes to read ibrdf flname Read data to file where flname is pathname of file to read ibrpp Conduct a parallel poll ibrsc v Request release system control ibrsv v Request service ibsad v Change secondary address ibsic Send interface clear ibsre v Set clear remote enable line ibstop Abort asynchronous operation ibtmo v Change disable time limit ibwait mask Wait for selected event where mask is a hex or decimal integer or a list of mask bit mnemonics such as ibwait TIMO CMPL ibwrt wrtbuf Write data ibwrta wrtbuf Write data asynchronously ibwrtf flname Write data from a file where flname is pathname of file to write Table 6 3 Syntax for Multi Device NI 488 2 Calls in Interactive Control Routine Syntax Description AllSpoll addrlist Serial poll multiple devices DevClear address Clear a device DevClearList addrlist Clear multiple devices EnableLocal addrlist Enable local control EnableRemote addrlist Enable remote control FindLstn padlist limit Find all Listeners Table 6 2 Syntax for Board Level Traditional NI 488 2 Calls in Interactive Control Continued Syntax Description Chapter 6 Interactive Control Utility NI 488 2 User Manual for Windows 6
62. When should I use the Interactive Control utility You can use the Interactive Control utility to test and verify instrument communication troubleshoot problems and develop your application For more information refer to Chapter 6 Interactive Control Utility How do I use an NI 488 2 language interface For information about using NI 488 2 language interfaces refer to Chapter 3 Developing Your NI 488 2 Application Appendix E Windows NT Troubleshooting and Common Questions NI 488 2 User Manual for Windows E 4 National Instruments Corporation What do I need to know to communicate properly with my GPIB instrument Refer to the documentation that came from the instrument manufacturer The command sequences you use are dependent on the specific instrument The documentation for each instrument should include the GPIB commands you need to communicate with it In most cases device level traditional NI 488 2 calls are sufficient for communicating with instruments For more information refer to Chapter 3 Developing Your NI 488 2 Application How can I easily start communicating with my GPIB instrument Use the NI 488 2 Communicator for simple instrument communication To start the NI 488 2 Communicator select Start Programs National Instruments NI 488 2 Explore GPIB From there right click on the GPIB instrument in the right window frame Then choose Communicate With Instrument What can I do to check for errors in m
63. a GPIB instrument using the NI 488 2 Communicator follow these steps 1 Make sure that you have already scanned for instruments as described in the previous section Scan for GPIB Instruments 2 Start the NI 488 2 Communicator by selecting the GPIB instrument in the right window frame of Measurement amp Automation Explorer right clicking and choosing Communicate with Instrument as shown in Figure 2 7 Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 8 National Instruments Corporation Figure 2 7 Select Communicate with Instrument Figure 2 8 shows the NI 488 2 Communicator Figure 2 8 NI 488 2 Communicator Chapter 2 Measurement amp Automation Explorer National Instruments Corporation 2 9 NI 488 2 User Manual for Windows 3 Choose Query to write a command to the instrument then read a response back Choose Write to write a command to the instrument Or choose Read to read a response from the instrument Advanced Communication For more advanced interactive communication with GPIB instruments run the Interactive Control utility by following these steps 1 Select the GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click and choose Interactive Control as shown in Figure 2 9 Figure 2 9 Select Interactive Control Utility 2 Type in NI 488 2 API calls interactively to communicate with the GPIB
64. adIbcntl return thread specific ibcntl In your application instead of accessing the per process NI 488 2 globals substitute a call to get the corresponding per thread NI 488 2 global For example the following line of code if ibsta amp ERR could be replaced by if ThreadIbsta amp ERR A quick way to convert your application to use per thread NI 488 2 globals is to add the following define lines at the top of your C file define ibsta ThreadIbsta define iberr ThreadIberr define ibcnt ThreadIbcnt define ibcntl ThreadIbcntl Note If you are using ibnotify in your application see the Asynchronous Event Notification in Win32 NI 488 2 Applications section of this chapter the ibnotify callback is executed in a separate thread that is created by the NI 488 2 driver Therefore if your application makes NI 488 2 calls from the ibnotify callback function and makes NI 488 2 calls from other places you must use the ThreadIbsta ThreadIberr ThreadIbcnt and ThreadIbcntl functions described in this section instead of the per process NI 488 2 globals Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation 7 11 NI 488 2 User Manual for Windows Device Level Calls and Bus Management The device level traditional NI 488 2 calls are designed to perform all of the GPIB management for your application However the NI 488 2 driver can handle bus management only when the GPIB interface
65. ages refer to the topic Multiline Interface Messages in the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select an interface under Devices and Interfaces in the left window frame right click and select NI 488 2 Help to view the online help System Configuration Effects on HS488 Maximum HS488 data transfer rates can be limited by your host computer and GPIB system setup For example when using a PC compatible computer with PCI bus the maximum obtainable transfer rate is 8 Mbytes s but when using a PC compatible computer with ISA bus the maximum transfer rate obtainable is only 2 Mbytes s The same IEEE 488 cabling constraints for a 350 ns T1 delay apply to HS488 As you increase the amount of cable in your GPIB configuration the maximum data transfer rate using HS488 decreases For example two HS488 devices connected by two meters of cable can transfer data faster than four HS488 devices connected by 4 m of cable Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 4 National Instruments Corporation Waiting for GPIB Conditions You can use the ibwait function to obtain the current ibsta value or to suspend your application until a specified condition occurs on the GPIB If you use ibwait with a parameter of zero it immediately updates ibsta and ret
66. all Pname Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 16 National Instruments Corporation where Pname is the name of the pointer to the function They are followed by the function s list of parameters as described in the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces right click and choose NI 488 2 Help to view the online help Below is an example of how to cast the function pointer and how the parameter list is set up for ibdev and ibonl functions int _stdcall Pibdev int ud int pad int sad int tmo int eot int eos int _stdcall Pibonl int ud int v Next your Win32 application needs to use GetProcAddress to get the addresses of the global status variables and functions your application needs The following code fragment shows you how to get the addresses of the pointers to the status variables and any functions your application needs Pointers to NI 488 2 global status variables int Pibsta int Piberr long Pibcntl static int __stdcall Pibdev int ud int pad int sad int tmo int eot int eos static int __stdcall Pibonl int ud int v Pibsta int GetProcAddress Gpib32Lib LPCSTR user_ibsta Piberr int GetProcAddress Gpib32Lib
67. ample button to view sample C C code that performs a simple query of a GPIB instrument Interactive Instrument Control Before you begin writing your application you might want to use the Interactive Control utility to communicate with your instruments interactively by typing in commands from the keyboard rather than issuing them from an application You can use the Interactive Control utility to learn to communicate with your instruments using the NI 488 2 API For specific device communication instructions refer to the user manual that came with your instrument For information about using the Interactive Control utility and detailed examples refer to Chapter 6 Interactive Control Utility To start Interactive Control launch Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Then select the GPIB interface under Devices and Interfaces in the left window frame right click and choose Interactive Control To establish simple communication use the calls modeled in the sample provided by the NI 488 2 Communicator The first NI 488 2 API call to make is ibdev After that you can use ibwrt and ibrd to send commands to and read responses from the GPIB instrument Finally use ibonl to put the device handle offline when you are finished Refer to Chapter 6 Interactive Control Utility for more information Choosing Your Programming Methodology Based on your development environm
68. ar Then start the NI 488 2 application that you want to monitor NI Spy records all NI 488 2 calls made Figure 5 2 shows the main NI Spy window with several recorded calls Chapter 5 NI Spy Utility National Instruments Corporation 5 3 NI 488 2 User Manual for Windows Figure 5 2 NI Spy Application Using the NI Spy Online Help The NI Spy utility has built in context sensitive online help that describes all NI Spy features To access it select Help from the NI Spy menu You can also access the online help by clicking on the question mark button in the NI Spy toolbar and then clicking on the area of the screen about which you have a question Locating Errors with NI Spy All NI 488 2 calls returned with an error are displayed in red within the main NI Spy window Viewing Properties for Recorded Calls To see the detailed properties of any call recorded in the main NI Spy window double click on the call The Call Properties window appears It contains general input output and buffer information Chapter 5 NI Spy Utility NI 488 2 User Manual for Windows 5 4 National Instruments Corporation Exiting NI Spy When you exit NI Spy its current configuration is saved and used to configure NI Spy when you start it again Unless you save the data captured in NI Spy before you exit that information is lost To save the captured data click on the red X button on the toolbar and select File Save As to save the data i
69. ario 905 785 0085 905 785 0086 Canada Qu bec 514 694 8521 514 694 4399 Denmark 45 76 26 00 45 76 26 02 Finland 09 725 725 11 09 725 725 55 France 0 1 48 14 24 24 0 1 48 14 24 14 Germany 089 741 31 30 089 714 60 35 Hong Kong 2645 3186 2686 8505 India 91805275406 91805275410 Israel 03 6120092 03 6120095 Italy 02 413091 02 4139215 Japan 03 5472 2970 03 5472 2977 Korea 02 596 7456 02 596 7455 Mexico D F 5 280 7625 5 520 3282 Mexico Monterrey 8 357 7695 8 365 8543 Netherlands 0348 433466 0348 430673 Norway 32 84 84 00 32 84 86 00 Singapore 2265886 2265887 Spain Madrid 91 640 0085 91 640 0533 Spain Barcelona 93 582 0251 93 582 4370 Sweden 08 587 895 00 08 730 43 70 Switzerland 056 200 51 51 056 200 51 55 Taiwan 02 2377 1200 02 2737 4644 United Kingdom 01635 523545 01635 523154 United States 512 795 8248 512 794 5678 National Instruments Corporation G 1 NI 488 2 User Manual for Windows Glossary Prefix Meaning Value n nano 10 9 m milli 10 3 M mega 106 A acceptor handshake Listeners use this GPIB interface function to receive data and all devices use it to receive commands See source handshake and handshake access board The GPIB board that controls and communicates with the devices on the bus that are attached to it ANSI American National Standards Institute API Application Programming Inter
70. assert SRQ when ESB or MAV are set or when a manufacturer defined condition occurs Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation 7 13 NI 488 2 User Manual for Windows Automatic Serial Polling You can enable automatic serial polling if you want your application to conduct a serial poll automatically when the SRQ line is asserted The autopolling procedure occurs as follows 1 To enable autopolling use the configuration function ibconfig with option IbcAUTOPOLL or the NI 488 2 Configuration utility Autopolling is enabled by default 2 When the SRQ line is asserted the driver automatically serial polls the open devices 3 Each positive serial poll response bit 6 or hex 40 is set is stored in a queue associated with the device that sent it The RQS bit of the device status word ibsta is set 4 The polling continues until SRQ is unasserted or an error condition is detected 5 To empty the queue use the ibrsp function ibrsp returns the first queued response Other responses are read in first in first out FIFO fashion If the RQS bit of the status word is not set when ibrsp is called a serial poll is conducted and returns the response received Empty the queue as soon as an automatic serial poll occurs because responses might be discarded if the queue is full 6 If the RQS bit of the status word is still set after ibrsp is called the response byte queue contains at least
71. ay Interactive utility online help function table 6 11 help option function Interactive utility 6 11 Index NI 488 2 User Manual for Windows I 6 National Instruments Corporation HS488 high speed data transfers 7 2 to 7 3 enabling HS488 7 2 to 7 3 setting cable length 7 2 system configuration effects 7 3 HS488 configuration message 7 3 I ibask function 7 3 ibclr function clearing devices example 3 10 using in Interactive Control example 6 4 ibcnt and ibcntl variables 3 8 ibconfig function configuring GPIB board as CIC 7 2 configuring NI 488 2 driver 4 4 determining assertion of EOI line 7 2 enabling autopolling 7 13 enabling high speed data transfers 7 2 to 7 3 ibdev function opening devices example 3 9 to 3 10 using in Interactive Control example 6 3 ibeos function 7 1 ibeot function 7 1 iberr error variable 3 7 to 3 8 ibnotify function asynchronous event notification in Win32 applications example 7 5 to 7 9 calling 7 4 to 7 5 ibonl function placing device offline example 3 10 3 13 using in Interactive Control example 6 5 ibppc function conducting parallel polls 7 17 to 7 18 unconfiguring device for parallel polling 7 18 ibrd function communicating with device example 3 10 using in Interactive Control example 6 4 ibrpp function 7 18 ibrsp function automatic serial polling 7 13 SRQ and serial polling 7 14 ibsta See status word ibsta ibwait function
72. bility to carry out an operation or when a particular capability has been disabled in the software and a call is made that requires the capability Solutions Check the validity of the call or make sure your GPIB interface and the driver both have the needed capability EFSO 12 EFSO results when an ibrdf or ibwrtf call encounters a problem performing a file operation Specifically this error indicates that the function is unable to open create seek write or close the file being accessed The specific operating system error code for this condition is contained in ibcntl Solutions Possible solutions for this error are as follows Make sure the filename path and drive that you specified are correct Make sure that the access mode of the file is correct Make sure there is enough room on the disk to hold the file EBUS 14 EBUS results when certain GPIB bus errors occur during device functions All device functions send command bytes to perform addressing and other bus management Devices are expected to accept these command bytes within the time limit specified by the default configuration or the ibtmo function EBUS results if a timeout occurred while sending these command bytes Appendix C Error Codes and Solutions NI 488 2 User Manual for Windows C 8 National Instruments Corporation Solutions Possible solutions for this error are as follows Verify that the instrument is operating
73. ce n Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation 7 7 NI 488 2 User Manual for Windows return 0 set up the asynchronous event notification on RQS ibnotify ud RQS MyCallback NULL if ibsta amp ERR printf ibnotify call failed n return 0 while ReadingsTaken lt 1000 amp amp DeviceError Your application does useful work here For example it might process the device readings or do any other useful work disable notification ibnotify ud 0 NULL NULL Call the ibonl function to disable the hardware and software ibonl ud 0 return 1 int __stdcall MyCallback int LocalUd int LocalIbsta int LocalIberr long LocalIbcntl void RefData char SpollByte char ReadBuffer 40 If the ERR bit is set in LocalIbsta then print an error message and return if LocalIbsta amp ERR printf GPIB error d has occurred No more callbacks n LocalIberr DeviceError TRUE return 0 Read the serial poll byte from the device If the ERR bit is set in ibsta then print an error message and return LocalIbsta ibrsp LocalUd amp SpollByte if LocalIbsta amp ERR printf ibrsp failed No more callbacks n DeviceError TRUE Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 8 National Instruments Corporation return 0 If the returned status byte equals the
74. ce so that the GPIB interface is Controller In Charge CIC The only argument of SendIFC is the GPIB interface number typically 0 for GPIB0 Step 2 Determine the GPIB Address of Your Device Use FindLstn to find all the devices attached to the GPIB The FindLstn function requires the following parameters Interface number typically 0 for GPIB0 A list of primary addresses terminated with the NOADDR constant A list for reported GPIB addresses of devices found listening on the GPIB Limit which is the number of the GPIB addresses to report Use FindLstn to test for the presence of all of the primary addresses that are passed to it If a device is present at a particular primary address then the primary address is stored in the GPIB addresses list Otherwise all secondary addresses of the given primary address are tested and the GPIB address of any devices found are stored in the GPIB addresses list When you have the list of GPIB addresses you can determine which one corresponds to your instrument and use it for subsequent calls Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 12 National Instruments Corporation Alternately if you already know your GPIB device s primary and secondary address you can create an appropriate GPIB address to use in subsequent NI 488 2 calls as follows a GPIB address is a 16 bit value that contains the primary address in the low by
75. ce status code D 2 to D 3 EDVR error conditions D 1 to D 2 Windows NT E 1 to E 4 common questions E 2 to E 4 examining NT system log using Event Viewer E 2 using diagnostic tools E 1 to E 2 verifying NI 488 2 installation E 1 to E 2 viewing or changing GPIB interface settings Windows 98 95 2 14 to 2 15 Windows NT 2 15 to 2 16
76. cimal notation Mnemonic constant of each bit set in ibsta Mnemonic value of the error variable iberr if an error exists the ERR bit is set in ibsta Count value for each read write or command function Data received from your instrument Getting Started with Interactive Control This section shows you how to use the Interactive Control utility to test a sequence of NI 488 2 calls To start Interactive Control launch Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB From the Explorer select a GPIB interface under Devices and Interfaces in the left window frame right click and select Interactive Control as shown in Figure 6 1 Chapter 6 Interactive Control Utility NI 488 2 User Manual for Windows 6 2 National Instruments Corporation Figure 6 1 Select Interactive Control Utility When the Interactive Control utility starts it displays the following banner message Interactive Control Copyright 1999 National Instruments Corporation All rights reserved Type help for help or q to quit First you must open either an interface handle or device handle to use for further NI 488 2 calls Use ibdev to open a device handle ibfind to open an interface handle or the set 488 2 command to switch to a 488 2 prompt For help on any Interactive Control command type in help followed by the command for example help ibdev or help s
77. ction to handle NI 488 2 errors This function takes the device offline and closes the application If the function is declared as void gpiberr char msg function prototype Then your application invokes it as follows if ibsta amp ERR gpiberr NI 488 2 error General Program Steps and Examples The following steps show you how to use the device level traditional NI 488 2 calls in your application The NI 488 2 software includes the source code for an example written in C devquery c and the source code for the example written to use direct entry to access gpib 32 dll dlldevquery c The NI 488 2 software also includes a sample program written in Visual Basic devquery frm Initialization Step 1 Open a Device Use ibdev to open a device handle The ibdev function requires the following parameters Connect board index typically 0 for GPIB0 Primary address for the GPIB instrument refer to the instrument user manual or use the FindLstn function to dynamically determine the GPIB address of your GPIB device as described in Step 2 Determine the GPIB Address of Your Device in the section Applications That Use Multiple Interfaces or Communicate with Multiple GPIB Devices later in this chapter Secondary address for the GPIB instrument 0 if the GPIB instrument does not use secondary addressing Timeout period typically set to T10s which is 10 seconds End of transfer mode t
78. d and the access of the globals is not protected by synchronization In this case synchronization of access to these globals is not necessary because of the way they are used in the application only a single thread is writing the global values and that thread only adds information increases the count or adds another reading to the array of floats int __stdcall MyCallback int ud int LocalIbsta int LocalIberr long LocalIbcntl void RefData int ReadingsTaken 0 float Readings 1000 BOOL DeviceError FALSE char expectedResponse 0x43 int main int ud Assign a unique identifier to the device and store it in the variable ud ibdev opens an available device and assigns it to access GPIB0 with a primary address of 1 a secondary address of 0 a timeout of 10 seconds the END message enabled and the EOS mode disabled If ud is less than zero then print an error message that the call failed and exit the program ud ibdev 0 connect board 1 primary address of GPIB device 0 secondary address of GPIB device T10s 10 second I O timeout 1 EOT mode turned on 0 EOS mode disabled if ud lt 0 printf ibdev failed n return 0 Issue a request to the device to send the data If the ERR bit is set in ibsta then print an error message that the call failed and exit the program ibwrt ud SEND DATA 9L if ibsta amp ERR printf unable to write to devi
79. ddress is made up of two parts a primary address and an optional secondary address The primary address is a number in the range 0 to 30 The Controller uses this address to form a talk or listen address that is sent over the GPIB when communicating with a device A talk address is formed by setting bit 6 the TA Talk Active bit of the GPIB address A listen address is formed by setting bit 5 the LA Listen Active bit of the GPIB address For example if a device is at address 1 the Controller sends hex 41 address 1 with bit 6 set to make the device a Talker Because the Controller is usually at primary address 0 it sends hex 20 address 0 with bit 5 set to make itself a Listener Figure A 1 shows the configuration of the GPIB address bits Figure A 1 GPIB Address Bits With some devices you can use secondary addressing A secondary address is a number in the range hex 60 to hex 7E When you use secondary addressing the Controller sends the primary talk or listen address of the device followed by the secondary address of the device Sending Messages across the GPIB Devices on the bus communicate by sending messages Signals and lines transfer these messages across the GPIB interface which consists of 16 signal lines and 8 ground return shield drain lines The 16 signal lines are discussed in the following sections Data Lines Eight data lines DIO1 through DIO8 carry both data and command messages Bit Position 7 6
80. device at the same time The advantage of parallel polling is that a single parallel poll can easily check up to eight individual devices at once In comparison eight separate serial polls would be required to check eight devices for their serial poll response bytes The value of the individual status bit ist determines the parallel poll response Implementing a Parallel Poll You can implement parallel polling with either the traditional or multi device NI 488 2 calls If you use multi device NI 488 2 calls to execute parallel polls you do not need extensive knowledge of the parallel polling messages However you should use the traditional NI 488 2 calls for parallel polling when the GPIB interface is not the Controller and the interface must configure itself for a parallel poll and set its own individual status bit ist Parallel Polling with Traditional NI 488 2 Calls Complete the following steps to implement parallel polling using traditional NI 488 2 calls Each step contains example code 1 Configure the device for parallel polling using the ibppc function unless the device can configure itself for parallel polling ibppc requires an 8 bit value to designate the data line number the ist sense and whether the function configures the device for the parallel poll The bit pattern is as follows 0 1 1 E S D2 D1 D0 E is 1 to disable parallel polling and 0 to enable parallel polling for that particular device S is 1 if th
81. device to be polled That device must also be addressed to talk See SPD SRQ Service Request The GPIB line that a device asserts to notify the CIC that the device needs servicing status byte The IEEE 488 2 defined data byte sent by a device when it is serially polled status word See ibsta synchronous Refers to the relationship between the GPIB driver functions and a process when executing driver functions is predictable the process is blocked until the driver completes the function System Controller The single designated Controller that can assert control become CIC of the GPIB by sending the Interface Clear IFC message Other devices can become CIC only by having control passed to them Glossary NI 488 2 User Manual for Windows G 8 National Instruments Corporation T TAD Talk Address See MTA Talker A GPIB device that sends data messages to Listeners TCT Take Control The GPIB command used to pass control of the bus from the current Controller to an addressed Talker timeout A feature of the GPIB driver that prevents I O functions from hanging indefinitely when there is a problem on the GPIB TLC An integrated circuit that implements most of the GPIB Talker Listener and Controller functions in hardware U ud Unit descriptor A variable name and first argument of each function call that contains the unit descriptor of the GPIB interface or other GPIB device that is the object of the functio
82. dle for ud and a mask of RQS CMPL END or TIMO If you are using board level calls you call ibnotify with a board handle for ud and a mask of any values except RQS or ERR The ibnotify mask bits are identical to the ibwait mask bits In the example of waiting for your Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation 7 5 NI 488 2 User Manual for Windows GPIB device to request service you might choose to pass ibnotify a mask with RQS for device level or SRQI for board level The callback function that you register with the ibnotify call is invoked by the NI 488 2 driver when one or more of the mask bits passed to ibnotify is TRUE The function prototype of the callback is as follows int __stdcall Callback int ud unit descriptor int ibsta ibsta value int iberr iberr value long ibcntl ibcntl value void RefData user defined reference data The callback function is passed a unit descriptor the current values of the NI 488 2 global variables and the user defined reference data that was passed to the original ibnotify call The NI 488 2 driver interprets the return value for the callback as a mask value that is used to automatically rearm the callback if it is non zero For a complete description of ibnotify refer to the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instrum
83. e Control Syntax The following special rules apply to making calls from the Interactive Control utility The ud or BoardId parameter is implied by the Interactive Control prompt therefore it is never included in the call The count parameter to functions is unnecessary because buffer lengths are automatically determined by Interactive Control Function return values are handled automatically by Interactive Control In addition to printing out the return ibsta value for the function it also prints other return values If you do not know what parameters are appropriate to pass to a given function call type in the function name and press lt Enter gt The Interactive Control utility then prompts you for each required parameter Number Syntax You can enter numbers in either hexadecimal or decimal format Hexadecimal numbers You must prefix hexadecimal numbers with 0x For example ibpad 0x16 sets the primary address to 16 hexadecimal 22 decimal Decimal numbers Enter the number only For example ibpad 22 sets the primary address to 22 decimal Chapter 6 Interactive Control Utility NI 488 2 User Manual for Windows 6 6 National Instruments Corporation String Syntax You can enter strings as an ASCII character sequence hex bytes or special symbols ASCII character sequence You must enclose the entire sequence in quotation marks Hex byte You must use a backslash character and an x fo
84. e device is to assert the assigned data line when ist is 1 and 0 if the device is to assert the assigned data line when ist is 0 D2 through D0 determine the number of the assigned data line The physical line number is the binary line number plus one For example DIO3 has a binary bit pattern of 010 The following example code configures a device for parallel polling using traditional NI 488 2 calls The device asserts DIO7 if its ist is 0 Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 18 National Instruments Corporation In this example the ibdev command opens a device that has a primary address of 3 has no secondary address has a timeout of 3 s asserts EOI with the last byte of a write operation and has EOS characters disabled The following call configures the device to respond to the poll on DIO7 and to assert the line in the case when its ist is 0 Pass the binary bit pattern 0110 0110 or hex 66 to ibppc include decl 32 h char ppr dev ibdev 0 3 0 T3s 1 0 ibppc dev 0x66 If the GPIB interface configures itself for a parallel poll you should still use the ibppc function Pass the interface index or an interface unit descriptor value as the first argument in ibppc Also if the individual status bit ist of the interface needs to be changed use the ibist function In the following example the GPIB interface is to configure itself to participate in a parallel poll It as
85. e you can connect to our Web sites around the world http www natinst com niglobal and access technical support http www natinst com support FTP Site To access our FTP site log in to our Internet host ftp natinst com as anonymous and use your e mail address such as yourname anywhere com as your password The support files and documents are located in the support directories Fax on Demand Support Fax on Demand is a 24 hour information retrieval system containing a library of documents in English on a wide range of technical information You can access Fax on Demand from a touch tone telephone at 512 418 1111 E Mail Support You can submit technical support questions to the applications engineering team through e mail at support natinst com Remember to include your name address and phone number so we can contact you with solutions and suggestions NI 488 2 User Manual for Windows F 2 National Instruments Corporation Telephone and Fax Support National Instruments has branch offices all over the world Use the following list to find the technical support number for your country If there is no National Instruments office in your country contact the source from which you purchased your software to obtain support Country Telephone Fax Australia 03 9879 5166 03 9879 6277 Austria 0662 45 79 90 0 0662 45 79 90 19 Belgium 02 757 00 20 02 757 03 11 Brazil 011 284 5011 011 288 8528 Canada Ont
86. eaded Win32 NI 488 2 Applications 7 9 Device Level Calls and Bus Management 7 11 Talker Listener Applications 7 11 Serial Polling 7 12 Service Requests from IEEE 488 Devices 7 12 Service Requests from IEEE 488 2 Devices 7 12 Automatic Serial Polling 7 13 Stuck SRQ State 7 13 Autopolling and Interrupts 7 13 SRQ and Serial Polling with Device Level Traditional NI 488 2 Calls 7 14 SRQ and Serial Polling with Multi Device NI 488 2 Calls 7 15 Example 1 Using FindRQS 7 15 Example 2 Using AllSpoll 7 16 Parallel Polling 7 17 Implementing a Parallel Poll
87. ent you can select a method for accessing the driver and based on your NI 488 2 programming needs you can choose how to use the NI 488 2 API Choosing a Method to Access the NI 488 2 Driver Applications can access the NI 488 2 dynamic link library DLL gpib 32 dll either by using an NI 488 2 language interface or by direct access Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 4 National Instruments Corporation NI 488 2 Language Interfaces You can use a language interface if your program is written in Microsoft Visual C C 2 0 or later Borland C C 4 0 or later or Microsoft Visual Basic 4 0 or later Otherwise you must access gpib 32 dll directly Direct Entry Access You can access the DLL directly from any programming environment that allows you to request addresses of variables and functions that a DLL exports gpib 32 dll exports pointers to each of the global variables and all the NI 488 2 calls Choosing How to Use the NI 488 2 API The NI 488 2 API has two subsets of calls to meet your application needs Both of these sets the traditional calls and the multi device calls are compatible across computer platforms and operating systems so you can port programs to other platforms with little or no source code modification For most applications the traditional NI 488 2 calls are sufficient If you have a complex configuration with one or more interfaces and multiple de
88. ents NI 488 2 Explore GPIB Then select an interface under Devices and Interfaces in the left window frame right click and select NI 488 2 Help to view the online help Note The ibnotify callback is executed in a separate thread of execution from the rest of your application If your application will be performing other NI 488 2 operations while it is using ibnotify use the per thread NI 488 2 globals that are provided by the ThreadIbsta ThreadIberr ThreadIbcnt and ThreadIbcntl functions described in the Writing Multithreaded Win32 NI 488 2 Applications section of this chapter In addition if your application needs to share global variables with the callback use a synchronization primitive for example a semaphore to protect access to any globals For more information about the use of synchronization primitives refer to the documentation about using Win32 synchronization objects that came with your development tools ibnotify Programming Example The following code is an example of how you can use ibnotify in your application Assume that your GPIB device is a multimeter that you program it to acquire a reading by sending SEND DATA The multimeter requests service when it has a reading ready and each reading is a floating point value Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 6 National Instruments Corporation In this example globals are shared by the Callback thread and the main threa
89. environment Running Existing NI 488 2 Applications Running Existing Win32 and Win16 NI 488 2 Applications The NI 488 2 software includes the necessary components to allow existing Win32 and Win16 NI 488 2 applications to run properly Running Existing DOS NI 488 2 Applications Under Windows 98 95 Make sure that no older version of the NI 488 2 DOS device driver is loaded from your config sys file a file located on the boot drive of your computer The older NI 488 2 DOS device driver is loaded with the following command line device path gpib com Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 18 National Instruments Corporation where path is the directory in which you installed the NI 488 2 DOS software for example c at gpib Delete this command line to ensure that the older NI 488 2 DOS driver does not load To configure the NI 488 2 software to run your existing DOS NI 488 2 applications complete the following steps after you install the NI 488 2 software and GPIB hardware First start Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB To enable NI 488 2 DOS support under Windows 98 95 follow these steps 1 Select a GPIB interface under Devices and Interfaces in Measurement amp Automation Explorer 2 Select Tools Settings NI 488 2 3 Enable or disable DOS support in the NI 488 2 Software Settings dial
90. equest Any device can drive the SRQ line to asynchronously request service from the Controller EOI end or identify Talker uses the EOI line to mark the end of a data message Controller uses the EOI line when it conducts a parallel poll National Instruments Corporation B 1 NI 488 2 User Manual for Windows B Status Word Conditions This appendix gives a detailed description of the conditions reported in the status word ibsta For information about how to use ibsta in your application program refer to the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select an interface under Devices and Interfaces in the left window frame right click and select NI 488 2 Help to view the online help Each bit in ibsta can be set for device calls dev board calls brd or both dev brd The following table shows the status word layout Mnemonic Bit Position Hex Value Type Description ERR 15 8000 dev brd NI 488 2 error TIMO 14 4000 dev brd Time limit exceeded END 13 2000 dev brd END or EOS detected SRQI 12 1000 brd SRQ interrupt received RQS 11 800 dev Device requesting service CMPL 8 100 dev brd I O completed LOK 7 80 brd Lockout State REM 6 40 brd Remote State CIC 5 20 brd Controller In Charge ATN 4 10 brd
91. er It includes extensive troubleshooting information and the answers to frequently asked questions To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces in the left window frame right click and choose NI 488 2 Help to view the online help National Instruments Corporation 5 1 NI 488 2 User Manual for Windows 5 NI Spy Utility This chapter introduces you to NI Spy a utility that monitors and records multiple National Instruments APIs for example NI 488 2 and VISA Overview NI Spy monitors records and displays the NI 488 2 calls made from Win32 Win16 and DOS NI 488 2 applications It is a useful tool for troubleshooting errors in your application and for verifying that the communication with your GPIB instrument is correct Starting NI Spy To start NI Spy launch Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces in the left window frame right click and select NI Spy as shown in Figure 5 1 Chapter 5 NI Spy Utility NI 488 2 User Manual for Windows 5 2 National Instruments Corporation Figure 5 1 Select NI Spy When you launch NI Spy it displays the main NI Spy window By default capture is off Start capture by clicking on the blue arrow button in the NI Spy toolb
92. er LACS is set whenever the GPIB interface detects that its listen address and secondary address if enabled has been sent either by the GPIB interface itself or by another Controller LACS is also set whenever the GPIB interface shadow handshakes as a result of the ibgts function LACS is cleared whenever the GPIB interface detects the Unlisten UNL command its own talk address Interface Clear IFC or that the ibgts function has been called without shadow handshake DTAS brd DTAS indicates whether the GPIB interface has detected a device trigger command DTAS is set whenever the GPIB interface as a Listener detects that the Group Execute Trigger GET command has been sent by another Controller DTAS is cleared on any call immediately following an ibwait call if the DTAS bit is set in the ibwait mask parameter DCAS brd DCAS indicates whether the GPIB interface has detected a device clear command DCAS is set whenever the GPIB interface detects that the Device Clear DCL command has been sent by another Controller or whenever the GPIB interface as a Listener detects that the Selected Device Clear SDC command has been sent by another Controller If you use the ibwait or ibnotify function to wait for DCAS and the wait is completed DCAS is cleared from ibsta after the next NI 488 2 call The same is true of reads and writes If you call a read or write function such as ibwrt or Send and DCAS is set in ibsta the I O operatio
93. error codes table C 1 error conditions communication errors 4 5 repeat addressing 4 5 termination method 4 5 configuration errors 4 4 Interactive Control error information 6 12 timing errors 4 4 error variable iberr 3 7 to 3 8 ESAC error code C 5 ESRQ error code C 8 to C 9 ESTB error code C 8 ETAB error code C 9 event notification See asynchronous event notification in Win32 applications Event Status bit ESB 7 12 execute function n times n function Interactive Control 6 11 execute indirect file function Interactive Control 6 11 execute previous function n times n function Interactive Control 6 11 existing applications debugging 4 3 running under Windows 98 95 DOS NI 488 2 applications 3 17 to 3 18 Win16 NI 488 2 applications 3 17 running under Windows NT 3 18 F fax and telephone support F 2 Fax on Demand support F 1 FindLstn routine determining GPIB address example 3 11 to 3 12 using in Interactive Control example 6 3 Index National Instruments Corporation I 5 NI 488 2 User Manual for Windows FindRQS routine description 7 15 SRQ and serial polling example 7 15 to 7 16 FTP support F 1 functions See NI 488 2 API G General Purpose Interface Bus See GPIB Getting Started Wizard 2 3 to 2 4 global variables 3 6 to 3 8 count variables ibcnt and ibcntl 3 8 debugging applications 4 2 to 4 3 error variable iberr 3 7 to 3 8 status word ibsta
94. et Chapter 6 Interactive Control Utility National Instruments Corporation 6 3 NI 488 2 User Manual for Windows If you want to use device level calls open a device handle using ibdev The following example shows you how to use ibdev to open a device assign it to access interface gpib0 choose a primary address of 6 with no secondary address set a timeout of 10 seconds enable the END message and disable the EOS mode ibdev enter board index 0 enter primary address 6 enter secondary address 0 enter timeout T10s enter EOI on last byte flag 1 enter end of string mode byte 0 ud0 If you enter a command and no parameters you are prompted for the necessary arguments If you already know the required arguments you can enter them from the command line as follows ibdev 0 6 0 T10s 1 0 ud0 If you do not know the GPIB primary and secondary address of your GPIB instrument use the FindLstn call as follows set 488 2 n where n is the index of your GPIB interface Use SendIFC to become controller in charge 488 2 0 SendIFC Next use FindLstn to find all the Listeners on the GPIB 488 2 0 FindLstn 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 The call returns the number of listeners found in ibcnt and then lists the found listeners count 1 count is the number of listeners found Listeners 5 Chapter 6 Interactive Control Utility NI 488 2 User Manual f
95. et of low level functions are called board level functions They access the interface directly and require you to handle the addressing and bus management protocol These functions give you the flexibility and control to handle situations such as the following Communicating with non compliant non IEEE 488 2 devices Altering various low level interface configurations Managing the bus in non typical ways Board level functions that an NI 488 2 application might use include the following ibcmd ibrd ibwrt and ibconfig For a detailed list refer to the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces right click and choose NI 488 2 Help to view the online help Using Multiple Interfaces and or Multiple Devices When your system includes an interface that must access multiple devices use the multi device NI 488 2 calls which can perform the following tasks with a single call Find the Listeners on the bus using FindLstn Find a device requesting service using FindRQS Determine the state of the SRQ line or wait for SRQ to be asserted using TestSRQ or WaitSRQ Address multiple devices to receive a command using SendList You can mix board level traditional NI 488 2 calls with the multi d
96. evice NI 488 2 calls to have access to all the NI 488 2 functionality Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 6 National Instruments Corporation Checking Status with Global Variables Each NI 488 2 API call updates four global variables to reflect the status of the device or interface that you are using These global status variables are the status word ibsta the error variable iberr and the count variables ibcnt and ibcntl They contain useful information about the performance of your application Your application should check these variables after each NI 488 2 call The following sections describe each of these global variables and how you can use them in your application Note If your application is a multithreaded application refer to the section Writing Multithreaded Win32 NI 488 2 Applications in Chapter 7 NI 488 2 Programming Techniques Status Word ibsta All NI 488 2 calls update a global status word ibsta which contains information about the state of the GPIB and the GPIB hardware The value stored in ibsta is the return value of all the traditional NI 488 2 calls except ibfind and ibdev You can examine various status bits in ibsta and use that information to make decisions about continued processing If you check for possible errors after each call using the ibsta ERR bit debugging your application is much easier ibsta is a 16 bit value A bit value of one 1
97. f NT devices Device Status Started GPIB Board Class Driver Started Automatic GPIB Device Class Driver Started Automatic You should also see one or more lines similar to the following Device Status Started GPIB Port Driver AT GPIB System GPIB Port Driver PCI GPIB System The GPIB Board Class Driver and the GPIB Device Class Driver should have a status of Started If not refer to the next section Examining the NT System Log Using the Event Viewer Appendix E Windows NT Troubleshooting and Common Questions NI 488 2 User Manual for Windows E 2 National Instruments Corporation At least one of the GPIB Port Drivers listed by the Devices applet should have a status of Started If not refer to the next section Examining the NT System Log Using the Event Viewer If the GPIB Class Driver lines are not present or at least one GPIB Port Driver line is not present the NI 488 2 software is not installed properly You should reinstall the NI 488 2 software from the NI 488 2 for Windows CD Examining the NT System Log Using the Event Viewer Windows NT maintains a system log If the NI 488 2 driver is unable to start it records entries in the system log explaining why it failed to start To examine the system log through the Event Viewer utility select Start Programs Administrative Tools Event Viewer Events that might appear in the system log include the following The system cannot locate
98. face ASCII American Standard Code for Information Interchange asynchronous An action or event that occurs at an unpredictable time with respect to the execution of a program automatic serial polling A feature of the GPIB software in which serial polls are executed automatically by the driver whenever a device asserts the GPIB SRQ line Also called autopolling B base I O address See I O address BIOS Basic Input Output System board level function A rudimentary function that performs a single operation Glossary NI 488 2 User Manual for Windows G 2 National Instruments Corporation C CFE Configuration Enable The GPIB command which precedes CFGn and is used to place devices into their configuration mode CFGn These GPIB commands CFG1 through CFG15 follow CFE and are used to configure all devices for the number of meters of cable in the system so HS488 transfers occur without errors CIC Controller In Charge The device that manages the GPIB by sending interface messages to other devices CPU Central processing unit D DAV Data Valid One of the three GPIB handshake lines See handshake DCL Device Clear The GPIB command used to reset the device or internal functions of all devices See SDC device level function A function that combines several rudimentary board operations into one function so that the user does not have to be concerned with bus management or other GPIB protocol matters
99. hapter describes Measurement amp Automation Explorer an interactive utility you can use with the NI 488 2 software To open Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Overview You can perform the following GPIB related tasks in Measurement amp Automation Explorer Establish basic communication with your GPIB instruments Scan for instruments connected to your GPIB interface Launch the NI 488 2 Getting Started Wizard to get started with GPIB instrument communication Launch the NI 488 2 Troubleshooting Wizard to troubleshoot GPIB and NI 488 2 problems Launch NI Spy to monitor NI 488 2 or VISA API calls to GPIB interfaces View information about your GPIB hardware and NI 488 2 software Reconfigure the GPIB interface settings Locate additional help resources for GPIB and NI 488 2 Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 2 National Instruments Corporation Starting Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Figure 2 1 shows Measurement amp Automation Explorer Figure 2 1 Measurement amp Automation Explorer Chapter 2 Measurement amp Automation Explorer National Instruments Corporation 2 3 NI 488 2 User Manual for Windows Getting Star
100. he Controller must then determine which device asserted the SRQ line and respond accordingly The most common method for SRQ detection and servicing is the serial poll This section describes how to set up your application to detect and respond to service requests from GPIB devices Service Requests from IEEE 488 Devices IEEE 488 devices request service from the GPIB Controller by asserting the GPIB SRQ line When the Controller acknowledges the SRQ it serial polls each open device on the bus to determine which device requested service Any device requesting service returns a status byte with bit 6 set and then unasserts the SRQ line Devices not requesting service return a status byte with bit 6 cleared Manufacturers of IEEE 488 devices use lower order bits to communicate the reason for the service request or to summarize the state of the device Service Requests from IEEE 488 2 Devices The IEEE 488 2 standard refined the bit assignments in the status byte In addition to setting bit 6 when requesting service IEEE 488 2 devices also use two other bits to specify their status Bit 4 the Message Available bit MAV is set when the device is ready to send previously queried data Bit 5 the Event Status bit ESB is set if one or more of the enabled IEEE 488 2 events occurs These events include power on user request command error execution error device dependent error query error request control and operation complete The device can
101. he control functions of the devices automatically access their respective interfaces Figure 1 2 Example of Multiboard System Configuration Configuration Requirements To achieve the high data transfer rate that the GPIB was designed for you must limit the number of devices on the bus and the physical distance between devices The following restrictions are typical A maximum separation of 4 m between any two devices and an average separation of 2 m over the entire bus A maximum total cable length of 20 m A maximum of 15 devices connected to each bus with at least two thirds powered on One GPIB Another GPIB Digital Voltometer Plotter Printer gpib0 gpib1 Chapter 1 Introduction National Instruments Corporation 1 3 NI 488 2 User Manual for Windows For high speed operation the following restrictions apply All devices in the system must be powered on Cable lengths must be as short as possible with up to a maximum of 15 m of cable for each system There must be at least one equivalent device load per meter of cable If you want to exceed these limitations you can use a bus extender to increase the cable length or a bus expander to increase the number of device loads You can order bus extenders and expanders from National Instruments National Instruments Corporation 2 1 NI 488 2 User Manual for Windows 2 Measurement amp Automation Explorer This c
102. he items in the list as they are highlighted 3 Start to use NI 488 2 Run an existing NI 488 2 application or Develop a new NI 488 2 application Troubleshoot NI 488 2 Problems To troubleshoot NI 488 2 problems run the NI 488 2 Troubleshooting Wizard Select Measurement amp Automation in the left window frame of Measurement amp Automation Explorer then choose Help Troubleshooting NI 488 2 Troubleshooting Wizard as shown in Figure 2 4 Chapter 2 Measurement amp Automation Explorer National Instruments Corporation 2 5 NI 488 2 User Manual for Windows Figure 2 4 Select NI 488 2 Troubleshooting Wizard Figure 2 5 show the Troubleshooting Wizard after it has tested a GPIB interface You can access online help for the Troubleshooting Wizard by clicking on the Help button Figure 2 5 NI 488 2 Troubleshooting Wizard Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 6 National Instruments Corporation Scan for GPIB Instruments To scan for connected GPIB instruments follow these steps 1 Make sure that your instrument is connected to the GPIB interface and powered on 2 Select the GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click and choose Scan for Instruments as shown in Figure 2 6 Figure 2 6 Select Scan for Instruments Each instrument that is found is listed in the right
103. icon under Start Settings Control Panel In the System Properties box that appears select the Device Manager tab and click on the View devices by type button at the top of the tab Check to see if the interface listing in the Device Manager appears with an exclamation point or X by it If it does click on the interface listing and then click on the Properties button to view the General tab for the interface In the Device Status section look for the status description and Appendix D Windows 98 95 Troubleshooting and Common Questions National Instruments Corporation D 3 NI 488 2 User Manual for Windows status code number Locate the error code in the following list to find out why your GPIB interface is not working properly Code 9 Windows had a problem reading information from the GPIB interface This problem can occur if you are using an older revision of the AT GPIB TNT or AT GPIB TNT PnP interface Contact National Instruments to upgrade your GPIB interface Code 22 The GPIB interface is disabled To enable the GPIB interface check the appropriate configuration checkbox in the Device Usage section of the General tab Code 24 The GPIB interface is not present or the Device Manager is unaware that the GPIB interface is present To solve this problem select the interface in the Device Manager and click on the Remove button Next click on the Refresh button At this point the system rescans the in
104. icrosoft Visual C C programming instructions 3 13 multiple interfaces or multiple GPIB devices becoming Controller In Charge 3 11 communicating with devices 3 12 determining GPIB address of device 3 11 to 3 12 general steps and examples 3 11 to 3 13 initialization 3 11 to 3 12 initializing devices 3 12 items to include 3 10 to 3 11 placing device offline 3 13 multithreaded Win32 NI 488 2 applications writing 7 9 to 7 10 N n execute previous function n times function Interactive Control 6 11 n execute function n times function Interactive Control 6 11 NDAC not data accepted line table A 3 NI Spy utility debugging applications 4 1 to 4 2 existing applications 4 3 using global status variables 4 2 to 4 3 exiting 5 4 locating errors 5 3 main window figure 5 3 online help 5 3 overview 5 1 performance considerations 5 4 starting 4 1 to 4 2 5 1 to 5 2 viewing properties for recorded calls 5 3 NI 488 2 API See also application development debugging asynchronous event notification in Win32 applications 7 4 to 7 9 calling ibnotify function 7 4 to 7 5 ibnotify programming example 7 5 to 7 9 communicating with one GPIB device 3 4 to 3 5 device level calls and bus management 7 11 getting started with NI 488 2 2 3 to 2 4 high speed data transfers 7 2 to 7 3 enabling HS488 7 2 to 7 3 system configuration effects 7 3 Interactive Control syntax 6 5 to 6 11 board level traditional
105. if LocalIbsta amp ERR printf ibwrt failed No more callbacks n DeviceError TRUE return 0 else return RQS Writing Multithreaded Win32 NI 488 2 Applications If you are writing a multithreaded NI 488 2 application and you plan to make all of your NI 488 2 calls from a single thread you can safely continue to use the traditional NI 488 2 global variables ibsta iberr ibcnt ibcntl The NI 488 2 global variables are defined on a per process basis so each process accesses its own copy of the NI 488 2 globals If you are writing a multithreaded NI 488 2 application and you plan to make NI 488 2 calls from more than a single thread you cannot safely continue to use the traditional NI 488 2 global variables without some form of synchronization for example a semaphore To understand why refer to the following example Assume that a process has two separate threads that make NI 488 2 calls thread 1 and thread 2 Just as thread 1 is about to examine one of the NI 488 2 globals it gets preempted and thread 2 is allowed to run Thread 2 proceeds to make several NI 488 2 calls that automatically update the NI 488 2 globals Later when thread 1 is allowed to run the NI 488 2 global that it is ready to examine is no longer in a known state and its value is no longer reliable The previous example illustrates a well known multithreading problem It is unsafe to access process global variables from multiple
106. igher using a three wire handshake The bus supports one System Controller usually a computer and up to 14 additional instruments The ANSI IEEE Standard 488 2 1992 extends IEEE 488 1 by defining a bus communication protocol a common set of data codes and formats and a generic set of common device commands Talkers Listeners and Controllers GPIB devices can be Talkers Listeners or Controllers A Talker sends out data messages Listeners receive data messages The Controller usually a computer manages the flow of information on the bus It defines the communication links and sends GPIB commands to devices Some devices are capable of playing more than one role A digital voltmeter for example can be a Talker and a Listener If your system has a National Instruments GPIB interface and software installed it can function as a Talker Listener and Controller Controller In Charge and System Controller You can have multiple Controllers on the GPIB but only one Controller at a time can be the active Controller or Controller In Charge CIC The CIC can be either active or inactive standby Control can pass from the current CIC to an idle Controller but only the System Controller usually a GPIB interface can make itself the CIC Appendix A GPIB Basics NI 488 2 User Manual for Windows A 2 National Instruments Corporation GPIB Addressing All GPIB devices and interfaces must be assigned a unique GPIB address A GPIB a
107. igure CFGn message 7 3 Configure Enable CFE message 7 3 Index National Instruments Corporation I 3 NI 488 2 User Manual for Windows Controller in Charge CIC active Controller as CIC A 1 becoming Controller In Charge example 3 11 making GPIB board CIC 7 11 System Controller as A 1 Controllers definition A 1 idle Controller A 1 monitoring by Talker Listener applications 7 11 to 7 12 System Controller A 1 count information in Interactive Control 6 12 count variables ibcnt and ibcntl 3 8 D data lines A 2 data transfers high speed HS488 7 2 to 7 3 enabling 7 2 to 7 3 system configuration effects 7 3 terminating 7 1 to 7 2 DAV data valid line table A 3 DCAS status word condition bit position hex value and type table 3 7 description B 5 Talker Listener applications 7 12 debugging See also NI Spy utility troubleshooting and common questions communication errors 4 5 repeat addressing 4 5 termination method 4 5 configuration errors 4 4 existing applications 4 3 global status variables 4 2 to 4 3 GPIB error codes table C 1 NI Spy 4 1 to 4 2 NI 488 2 error codes 4 3 other errors 4 6 timing errors 4 4 DevClearList routine example 3 12 Device Manager device status codes troubleshooting D 2 to D 3 device level calls and bus management 7 11 direct access to NI 488 2 dynamic link library 3 4 documentation conventions used in manual xii overview of NI 488 2 doc
108. igure from your application using ibconfig or reconfigure using the NI 488 2 Configuration utility Note National Instruments recommends using ibconfig to modify the configuration If your application uses ibconfig it works properly regardless of the previous configuration For more information about ibconfig refer to the description of ibconfig in the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces in the left window frame right click and choose NI 488 2 Help to view the online help Termination Method You should be aware of the data termination method that your device uses By default your NI 488 2 software is configured to send EOI on writes and terminate reads on EOI or a specific byte count If you send a command string to your device and it does not respond it might not be recognizing the end of the command In that case you need to send a termination message such as lt CR gt lt LF gt after a write command as follows ibwrt dev COMMAND x0A x0D 9 Chapter 4 Debugging Your Application NI 488 2 User Manual for Windows 4 6 National Instruments Corporation Other Errors If you experience other errors in your application refer to the NI 488 2 online help available through Measurement amp Automation Explor
109. indicates that a certain condition is in effect A bit value of zero 0 indicates that the condition is not in effect Each bit in ibsta can be set for device level traditional NI 488 2 calls dev board level traditional NI 488 2 calls and multi device NI 488 2 calls brd or all dev brd Table 3 1 shows the condition that each bit position represents the bit mnemonics and the type of calls for which the bit can be set For a detailed explanation of each status condition refer to Appendix B Status Word Conditions Table 3 1 Status Word Layout Mnemonic Bit Pos Hex Value Type Description ERR 15 8000 dev brd NI 488 2 error TIMO 14 4000 dev brd Time limit exceeded END 13 2000 dev brd END or EOS detected Chapter 3 Developing Your NI 488 2 Application National Instruments Corporation 3 7 NI 488 2 User Manual for Windows The language header file defines each of the ibsta status bits You can test for an ibsta status bit being set using the bitwise and operator amp in C C For example the ibsta ERR bit is bit 15 of ibsta To check for an NI 488 2 error use the following statement after each NI 488 2 call if ibsta amp ERR printf NI 488 2 error encountered Error Variable iberr If the ERR bit is set in ibsta an NI 488 2 error has occurred When an error occurs the error type is specified by iberr To check for an NI 488 2 error use the following statement after each NI 48
110. instrument in the Interactive Control utility For example you might use ibdev ibclr ibwrt ibrd and ibonl Type in help to view the online help for Interactive Control Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 10 National Instruments Corporation About Instrument Communication Refer to the documentation that came with your GPIB instrument for a description of the commands that your instrument understands Most instruments respond to the IDN command by returning an identification string Adding a New GPIB Instrument To add a new GPIB instrument in Measurement amp Automation Explorer follow these steps 1 Make sure that your instrument is connected to the GPIB interface and powered on 2 Scan for connected GPIB instruments For help refer to the section Scan for GPIB Instruments Each instrument that is powered on and connected to the selected interface is listed in the right window frame Figure 2 10 shows a successful scan where two instruments were detected Chapter 2 Measurement amp Automation Explorer National Instruments Corporation 2 11 NI 488 2 User Manual for Windows Figure 2 10 Scan for New Instrument After Scanning Note If the message Instruments not Found appears in the right window frame Scan for Instruments failed because it did not find any instruments Make sure that your GPIB instruments are properly connected to the GPIB interface with a
111. is CIC Controller In Charge Only the CIC is able to send command bytes to the devices on the bus to perform device addressing or other bus management activities Use one of the following methods to make your GPIB interface the CIC If your GPIB interface is configured as the System Controller default it automatically makes itself the CIC by asserting the IFC line the first time you make a device level call If your setup includes more than one Controller or if your GPIB interface is not configured as the System Controller use the CIC Protocol method To use the protocol issue the ibconfig function option IbcCICPROT or use the NI 488 2 Configuration utility to activate the CIC protocol If the interface is not CIC and you make a device level call with the CIC protocol enabled the following sequence occurs 1 The GPIB interface asserts the SRQ line 2 The current CIC serial polls the interface 3 The interface returns a response byte of hex 42 4 The current CIC passes control to the GPIB interface If the current CIC does not pass control the NI 488 2 driver returns the ECIC error code to your application This error can occur if the current CIC does not understand the CIC protocol If this happens you could send a device specific command requesting control for the GPIB interface Then use a board level ibwait command to wait for CIC Talker Listener Applications Although designed for Controller In
112. ith the END bit set if the END condition occurs before or during that call END is cleared when any I O operation is initiated Some applications might need to know the exact I O read termination mode of a read operation EOI by itself the EOS character by itself or EOI plus the EOS character You can use the ibconfig function option IbcEndBitIsNormal to enable a mode in which the END bit is set only when EOI is asserted In this mode if the I O operation completes because of the EOS character by itself END is not set The application should check the last byte of the received buffer to see if it is the EOS character Appendix B Status Word Conditions National Instruments Corporation B 3 NI 488 2 User Manual for Windows SRQI brd SRQI indicates that a GPIB device is requesting service SRQI is set whenever the GPIB interface is CIC the GPIB SRQ line is asserted and the automatic serial poll capability is disabled SRQI is cleared either when the GPIB interface ceases to be the CIC or when the GPIB SRQ line is unasserted RQS dev RQS appears in the status word only after a device level call and indicates that the device is requesting service RQS is set whenever one or more positive serial poll response bytes have been received from the device A positive serial poll response byte always has bit 6 asserted Automatic serial polling must be enabled it is enabled by default for RQS to automatically appear in ibsta You can
113. les reflect the number of bytes sent Using Interactive Control to Communicate with Devices Before you begin writing your application you might want to use the Interactive Control utility to communicate with your instruments interactively by typing in commands from the keyboard rather than from an application You can use the Interactive Control utility to learn to communicate with your instruments using the NI 488 2 API For specific device communication instructions refer to the user manual that came with your instrument For information about using the Interactive Control utility and detailed examples refer to Chapter 6 Interactive Control Utility Programming Models Applications That Communicate with a Single GPIB Device This section describes items you should include in your application and provides general program steps with an NI 488 2 example Items to Include Include the following items in your application Header files In a C application include the header files windows h and decl 32 h The standard Windows header file windows h contains definitions used by decl 32 h and decl 32 h contains prototypes for the NI 488 2 calls and constants that you can use in your application Error checking Check for errors after each NI 488 2 call Chapter 3 Developing Your NI 488 2 Application National Instruments Corporation 3 9 NI 488 2 User Manual for Windows Error handling Declare and define a fun
114. listed in the logical device templates that are part of the NI 488 2 Configuration utility an EDVR error condition occurs with ibcntl set to 0xE0140035 EDVR Error Condition with ibcntl Set to 0xE0320029 533594071 or 0xE1050029 519765975 If a call is made with an interface number that is assigned to a GPIB interface that is unusable because of a resource conflict an EDVR error condition occurs with ibcntl set to 0xE0320029 or 0xE1050029 This error is also returned if you remove a PCMCIA GPIB or PCMCIA GPIB while the driver is accessing it or if you try to access a PCMCIA GPIB when 32 bit PCMCIA drivers are not enabled EDVR Error Condition with ibcntl Set to 0xE0140004 535560188 This error might occur if the GPIB interface has not been correctly installed and detected by Windows For details on how to install the GPIB hardware refer to the online GPIB hardware guide which is available by choosing View Documentation from the NI 488 2 for Windows CD autorun screen EDVR Error Condition with ibcntl set to 0xE1030043 519897021 This error occurs if you have enabled DOS NI 488 2 support and attempted to run an existing NI 488 2 DOS application that was compiled with an older unsupported DOS language interface Troubleshooting Device Manager Problems If you are having trouble with your GPIB interface use the Windows Device Manager to troubleshoot your problems To start the Device Manager double click on the System
115. llowed by the hex value For example hex 40 is represented by x40 Special symbols Some instruments require special termination or end of string EOS characters that indicate to the device that a transmission has ended The two most common EOS characters are r and n r represents a carriage return character and n represents a linefeed character You can use these special characters to insert the carriage return and linefeed characters into a string as in IDN r n Address Syntax Some of the NI 488 2 calls have an address or address list parameter An address is a 16 bit representation of the GPIB device address The primary address is stored in the low byte and the secondary address if any is stored in the high byte For example a device at primary address 6 and secondary address 0x67 has an address of 0x6706 A NULL address is represented as 0xffff An address list is represented by a comma separated list of addresses such as 1 2 3 Interactive Control Commands Tables 6 1 and 6 2 summarize the syntax of the traditional NI 488 2 calls in the Interactive Control utility Table 6 3 summarizes the syntax of the multi device NI 488 2 calls in the Interactive Control utility Table 6 4 summarizes the auxiliary functions that you can use in the Interactive Control utility For more information about the function parameters use the online help available by typing in help If you enter only the function name the Interactive Control
116. mory resident Resident in RAM MLA My Listen Address A GPIB command used to address a device to be a Listener It can be any one of the 31 primary addresses MSA My Secondary Address The GPIB command used to address a device to be a Listener or a Talker when extended two byte addressing is used The complete address is a MLA or MTA address followed by an MSA address There are 31 secondary addresses for a total of 961 distinct listen or talk addresses for devices MTA My Talk Address A GPIB command used to address a device to be a Talker It can be any one of the 31 primary addresses multitasking The concurrent processing of more than one program or task Glossary NI 488 2 User Manual for Windows G 6 National Instruments Corporation N NDAC Not Data Accepted One of the three GPIB handshake lines See handshake NRFD Not Ready For Data One of the three GPIB handshake lines See handshake P parallel poll The process of polling all configured devices at once and reading a composite poll response See serial poll PC Personal computer PCI Peripheral Component Interconnect PIO See programmed I O PPC Parallel Poll Configure It is the GPIB command used to configure an addressed Listener to participate in polls PPD Parallel Poll Disable It is the GPIB command used to disable a configured device from participating in polls There are 16 PPD commands PPE Parallel Poll Enable It is the GPIB c
117. n UNL Unlisten The GPIB command used to unaddress any active Listeners UNT Untalk The GPIB command used to unaddress an active Talker National Instruments Corporation I 1 NI 488 2 User Manual for Windows Index Numbers Symbols repeat previous function function Interactive Control 6 11 filename execute indirect file function Interactive Control 6 11 turn ON display function Interactive Control 6 11 turn OFF display function Interactive Control 6 11 A active Controller See Controller in Charge CIC addresses See GPIB addresses AllSpoll routine description 7 15 SRQ and serial polling example 7 16 application development See also debugging NI 488 2 API accessing NI 488 2 driver 3 3 to 3 4 choosing a method 3 3 to 3 4 direct entry access 3 4 NI 488 2 language interfaces 3 4 checking status with global variables 3 6 to 3 8 count variables ibcnt and ibcntl 3 8 error variable iberr 3 7 to 3 8 status word ibsta 3 6 to 3 7 communicating with single GPIB device 3 8 to 3 10 clearing devices 3 10 device communication 3 10 general steps and examples 3 9 to 3 10 items to include 3 8 to 3 9 opening devices 3 9 to 3 10 placing device offline 3 10 instrument control interactive 3 3 simple using NI 488 2 Communicator 3 1 to 3 3 Interactive Control for communicating with devices 3 8 language specific instructions 3 13 to 3 17 Borland C C 3 13 direct entry
118. n a spy file After you save your data select File Exit to exit the NI Spy utility Performance Considerations NI Spy can slow down the performance of your NI 488 2 application and certain configurations of NI Spy have a larger impact on performance than others For example configuring NI Spy to record calls to an output file or to use full buffers might have a significant impact on the performance of both your application and your system For this reason use NI Spy only while you are debugging your application or in situations where performance is not critical National Instruments Corporation 6 1 NI 488 2 User Manual for Windows 6 Interactive Control Utility This chapter introduces you to the Interactive Control utility which lets you communicate with GPIB devices interactively Overview With the Interactive Control utility you communicate with the GPIB devices through functions you interactively type in at the keyboard For specific information about communicating with your particular device refer to the documentation that came with the device You can use the Interactive Control utility to practice communication with the instrument troubleshoot problems and develop your application The Interactive Control utility helps you to learn about your instrument and to troubleshoot problems by displaying the following information on your screen after you enter a command Results of the status word ibsta in hexade
119. n is aborted DCAS is cleared from ibsta after the next NI 488 2 call National Instruments Corporation C 1 NI 488 2 User Manual for Windows C Error Codes and Solutions This appendix lists a description of each error some conditions under which it might occur and possible solutions The following table lists the GPIB error codes Error Mnemonic iberr Value Meaning EDVR 0 System error ECIC 1 Function requires GPIB interface to be CIC ENOL 2 No Listeners on the GPIB EADR 3 GPIB interface not addressed correctly EARG 4 Invalid argument to function call ESAC 5 GPIB interface not System Controller as required EABO 6 I O operation aborted timeout ENEB 7 Nonexistent GPIB interface EDMA 8 DMA error EOIP 10 Asynchronous I O in progress ECAP 11 No capability for operation EFSO 12 File system error EBUS 14 GPIB bus error ESTB 15 Serial poll status byte queue overflow ESRQ 16 SRQ stuck in ON position ETAB 20 Table problem Appendix C Error Codes and Solutions NI 488 2 User Manual for Windows C 2 National Instruments Corporation EDVR 0 EDVR is returned when the interface or device name passed to ibfind or the interface index passed to ibdev cannot be accessed The global variable ibcntl contains an error code This error occurs when you try to access an interface or device that is not installed or configured properly EDVR is also returned if an in
120. n the length as an extra parameter For more information about function syntax for Visual Basic refer to the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces right click and choose NI 488 2 Help to view the online help Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 14 National Instruments Corporation Before you run your Visual Basic application include the niglobal bas and vbib 32 bas files in your application project file Direct Entry with C The following sections describe how to use direct entry with C gpib 32 dll Exports gpib 32 dll exports pointers to the global variables and all of the NI 488 2 calls Pointers to the global variables ibsta iberr ibcnt and ibcntl are accessible through these exported variables int user_ibsta int user_iberr int user_ibcnt long user_ibcntl Except for the functions ibbna ibfind ibrdf and ibwrtf all the NI 488 2 call names are exported from gpib 32 dll Thus to use direct entry to access a particular function and to get a pointer to the exported function you just need to call GetProcAddress passing the name of the function as a parameter For more information about the parameters to use when you invoke the function refer to the N
121. nd WaitSRQ Following are descriptions of each of the routines AllSpoll can serial poll multiple devices with a single call It places the status bytes from each polled instrument into a predefined array Then you must check the RQS bit of each status byte to determine whether that device requested service ReadStatusByte is similar to AllSpoll except that it only serial polls a single device It is also similar to the device level NI 488 2 ibrsp function FindRQS serial polls a list of devices until it finds a device that is requesting service or until it has polled all of the devices on the list The routine returns the index and status byte value of the device requesting service TestSRQ determines whether the SRQ line is asserted and returns to the program immediately WaitSRQ is similar to TestSRQ except that WaitSRQ suspends the application until either SRQ is asserted or the timeout period is exceeded The following examples use these calls to detect SRQ and then determine which device requested service In these examples three devices are present on the GPIB at addresses 3 4 and 5 and the GPIB interface is designated as bus index 0 The first example uses FindRQS to determine which device is requesting service and the second example uses AllSpoll to serial poll all three devices Both examples use WaitSRQ to wait for the GPIB SRQ line to be asserted Example 1 Using FindRQS This example shows
122. nd and ibdev return the status word ibsta in two forms a hex value in square brackets and a list of mnemonics in parentheses In the following example the status word is on the second line showing that the write operation completed successfully ud0 ibwrt IDN 0100 cmpl count 5 ud0 For more information about ibsta refer to Chapter 3 Developing Your NI 488 2 Application Table 6 4 Auxiliary Functions in Interactive Control Function Description set udname Select active device or interface where udname is the symbolic name of the new device or interface for example dev1 or gpib0 Call ibfind or ibdev initially to open each device or interface set 488 2 v Start using multi device NI 488 2 calls for interface v help Display the Interactive Control utility online help help option Display help information about option where option is any NI 488 2 or auxiliary call for example help ibwrt or help set Repeat previous function Turn OFF display Turn ON display n function Execute function n times where function represents the correct Interactive Control function syntax n Execute previous function n times filename Execute indirect file where filename is the pathname of a file that contains Interactive Control functions to be executed buffer option Set type of display used for buffers Valid options are full brief ascii and off Default is full q Exit or quit
123. nd choose Properties as shown in Figure 2 13 Figure 2 13 Select Properties Chapter 2 Measurement amp Automation Explorer National Instruments Corporation 2 15 NI 488 2 User Manual for Windows Figure 2 14 shows the NI 488 2 Configuration utility Properties page for an AT GPIB TNT Plug and Play interface Figure 2 14 View Interface Information under Windows 98 95 You can use the NI 488 2 Configuration utility to change the settings for your interface To view the online help click on the button in the upper right corner of the dialog box then click on the item you need help with Under Windows NT To view or change GPIB interface information follow these steps 1 Select a GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click and choose Properties as shown in Figure 2 13 Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 16 National Instruments Corporation Figure 2 15 shows the NI 488 2 Configuration utility Figure 2 15 View Interface Information under Windows NT 2 Select the correct GPIB interface and click on Configure You can use the NI 488 2 Configuration utility to change the settings for your interface To view the online help click on the Help button View GPIB Instrument Information To view GPIB instrument information follow these steps 1 Scan for connected GPIB instrument
124. nder Windows 98 95 2 18 Under Windows NT 2 19 Access Additional Help and Resources for NI 488 2 and GPIB 2 19 NI 488 2 Online Help 2 19 National Instruments GPIB Web Site 2 19 Contents NI 488 2 User Manual for Windows vi National Instruments Corporation GPIB ENET Network Settings Windows 98 95 Only 2 20 Assign IP Address 2 20 Configure Advanced IP Settings 2 20 Update GPIB ENET Firmware 2 20 Chapter 3 Developing Your NI 488 2 Application Simple Instrument Control 3 1 Interactive Instrument Control 3 3 Choosing Your Programming Methodology 3 3 Choosing a Method to Access the NI 488 2 Dri
125. nts Corporation device handle and frees the application from unneccessary device name requirements If you must modify a device template follow these steps Under Windows 98 95 To reconfigure GPIB device templates under Windows 98 95 follow these steps 1 Launch the Windows 98 95 Device Manager a Select Start Settings Control Panel b Double click on the System icon c Select the Device Manager tab 2 Select National Instruments GPIB Interfaces 3 Click on the Properties button 4 Select the Device Templates tab 5 Use the context sensitive help for more information Under Windows NT To reconfigure GPIB device templates under Windows NT follow these steps 1 Select a GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer right click and choose Properties to launch the NI 488 2 Configuration utility 2 Change the GPIB device templates Use the online help available in the NI 488 2 Configuration utility for more information Enable Disable NI 488 2 DOS Support Under Windows 98 95 To enable NI 488 2 DOS support under Windows 98 95 follow these steps 1 Select a GPIB interface under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer 2 Select Tools Settings NI 488 2 3 Enable or disable DOS support in the NI 488 2 Settings dialog box Chapter 2 Measurement amp Automation Ex
126. oduct and company names mentioned herein are trademarks or trade names of their respective companies WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS National Instruments products are not designed with components and testing for a level of reliability suitable for use in or in connection with surgical implants or as critical components in any life support systems whose failure to perform can reasonably be expected to cause significant injury to a human Applications of National Instruments products involving medical or clinical treatment can create a potential for death or bodily injury caused by product failure or by errors on the part of the user or application designer Because each end user system is customized and differs from National Instruments testing platforms and because a user or application designer may use National Instruments products in combination with other products in a manner not evaluated or contemplated by National Instruments the user or application designer is ultimately responsible for verifying and validating the suitability of National Instruments products whenever National Instruments products are incorporated in a system or application including without limitation the appropriate design process and safety level of such system or application National Instruments Corporation v NI 488 2 User Manual for Windows Contents About This Manual Overview of the NI 488 2 Documentation
127. og box You can now run your existing DOS NI 488 2 applications Running Existing DOS NI 488 2 Applications under Windows NT To run DOS NI 488 2 applications you must enable NI 488 2 DOS support under Windows NT To enable NI 488 2 DOS support under Windows NT follow these steps 1 Open your config nt file located in the Windows NT system32 directory for example c windows system32 2 Find the following lines of code REM To run DOS GPIB applications uncomment the REM following line REM device lt path gt doswin16 gpib nt com where lt path gt is the directory in which you installed the NI 488 2 software 3 Remove REM from the last line so that it reads device lt path gt doswin16 gpib nt com To disable DOS support add REM back to the line of code where it was removed National Instruments Corporation 4 1 NI 488 2 User Manual for Windows 4 Debugging Your Application This chapter describes several ways to debug your application NI Spy The NI Spy utility monitors NI 488 2 API calls made by NI 488 2 applications It records NI 488 2 API input and output values from all Win32 Win16 and DOS NI 488 2 applications For more information about NI Spy refer to its online help by selecting Help from the NI Spy menu To start NI Spy launch Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Device
128. ome examples ibtmo called with a value not in the range 0 through 17 ibeos called with meaningless bits set in the high byte of the second parameter ibpad or ibsad called with invalid addresses ibppc called with invalid parallel poll configurations A board level traditional NI 488 2 call made with a valid device descriptor or a device level traditional NI 488 2 call made with a board descriptor A multi device NI 488 2 call made with an invalid address PPollConfig called with an invalid data line or sense bit Solutions Possible solutions for this error are as follows Make sure that the parameters passed to the NI 488 2 call are valid Do not use a device descriptor in a board function or vice versa Appendix C Error Codes and Solutions National Instruments Corporation C 5 NI 488 2 User Manual for Windows ESAC 5 ESAC results when ibsic ibsre SendIFC or EnableRemote is called when the GPIB interface does not have System Controller capability Solutions Give the GPIB interface System Controller capability by calling ibrsc 1 or by using the NI 488 2 Configuration utility to configure that capability into the software EABO 6 EABO indicates that an I O operation has been canceled usually due to a timeout condition Other causes are calling ibstop or receiving the Device Clear message from the CIC while performing an I O operation Frequently the I
129. ommand used to enable a configured device to participate in polls and to assign a DIO response line There are 16 PPE commands PPU Parallel Poll Unconfigure It is the GPIB command used to disable any device from participating in polls programmed I O Low speed data transfer between the GPIB board and memory in which the CPU moves each data byte according to program instructions See DMA R RAM Random access memory resynchronize The GPIB software and the user application must resynchronize after asynchronous I O operations have completed RQS Request Service Glossary National Instruments Corporation G 7 NI 488 2 User Manual for Windows S s Seconds SDC Selected Device Clear The GPIB command used to reset internal or device functions of an addressed Listener See DCL semaphore An object that maintains a count between zero and some maximum value limiting the number of threads that are simultaneously accessing a shared resource serial poll The process of polling and reading the status byte of one device at a time See parallel poll service request See SRQ source handshake The GPIB interface function that transmits data and commands Talkers use this function to send data and the Controller uses it to send commands See acceptor handshake and handshake SPD Serial Poll Disable The GPIB command used to cancel an SPE command SPE Serial Poll Enable The GPIB command used to enable a specific
130. on bit position hex value and type table 3 7 description B 3 M manual See documentation Measurement amp Automation Explorer 2 1 to 2 20 accessing help and resources National Instruments GPIB Web site 2 19 NI 488 2 online help 2 19 adding new GPIB instruments 2 10 to 2 11 changing GPIB device templates 2 17 to 2 18 Windows 98 95 2 18 Windows NT 2 18 communicating with GPIB instruments 2 7 to 2 10 advanced communication 2 9 instrument commands 2 10 query read write communication 2 7 to 2 9 enabling disabling NI 488 2 DOS support 2 18 to 2 19 Windows 98 95 2 18 Windows NT 2 19 getting started with NI 488 2 2 3 to 2 4 GPIB ENET network settings Windows 98 95 assigning IP address 2 20 configuring advanced IP settings 2 20 updating GPIB ENET firmware 2 20 monitoring recording and displaying NI 488 2 calls 2 13 overview 2 1 scanning for GPIB instruments 2 6 to 2 7 starting 2 2 troubleshooting NI 488 2 problems 2 4 to 2 5 viewing GPIB instrument information 2 16 to 2 17 viewing NI 488 2 software version 2 12 viewing or changing GPIB interface settings 2 14 to 2 16 Windows 98 95 2 14 to 2 15 Windows NT 2 15 to 2 16 Message Available MAV bit 7 12 messages sending across GPIB A 2 to A 3 data lines A 2 handshake lines A 3 Index NI 488 2 User Manual for Windows I 8 National Instruments Corporation interface management lines A 3 Microsoft Visual Basic 3 13 to 3 14 M
131. on does not have built in error detection handling you can use NI Spy to determine which NI 488 2 call is failing To start NI Spy launch Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces in the left window frame right click and choose NI Spy After you have an NI Spy capture file you can use NI Spy to search for failed NI 488 2 calls by searching for calls with the ERR bit set Once you know which NI 488 2 call fails refer to Appendix B Status Word Conditions and Appendix C Error Codes and Solutions for help understanding why the NI 488 2 call failed This information is also available in the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces in the left window frame right click and choose NI 488 2 Help to view the online help NI 488 2 Error Codes The error variable is meaningful only when the ERR bit in the status variable ibsta is set For a detailed description of each error and possible solutions refer to Appendix C Error Codes and Solutions Chapter 4 Debugging Your Application NI 488 2 User Manual for Windows 4 4 National Instruments Corporation Configuration Errors Several applications
132. ondary address MSA The GPIB board has both a GPIB address and an I O address GPIB board Refers to the National Instruments family of GPIB interfaces GTL Go To Local The GPIB command used to place an addressed Listener in local front panel control mode H handshake The mechanism used to transfer bytes from the source handshake function of one device to the acceptor handshake function of another device DAV NRFD and NDAC three GPIB lines are used in an interlocked fashion to signal the phases of the transfer so that bytes can be sent asynchronously for example without a clock at the speed of the slowest device For more information about handshaking refer to the ANSI IEEE Standard 488 1 1987 Glossary NI 488 2 User Manual for Windows G 4 National Instruments Corporation hex Hexadecimal a number represented in base 16 For example decimal 16 is hex 10 high level function See device level function HS488 A high speed data transfer protocol for IEEE 488 This protocol increases performance for GPIB reads and writes up to 8 Mbytes s depending on your system Hz Hertz I ibcnt After each NI 488 I O function this global variable contains the actual number of bytes transmitted iberr A global variable that contains the specific error code associated with a function call that failed ibsta At the end of each function call this global variable status word contains status information IEE
133. one more response byte If this happens continue to call ibrsp until RQS is cleared Stuck SRQ State If autopolling is enabled and the GPIB interface detects an SRQ the driver serial polls all open devices connected to that interface The serial poll continues until either SRQ unasserts or all the devices have been polled If no device responds positively to the serial poll or if SRQ remains in effect because of a faulty instrument or cable a stuck SRQ state is in effect If this happens during an ibwait for RQS the driver reports the ESRQ error If the stuck SRQ state happens no further polls are attempted until an ibwait for RQS is made When ibwait is issued the stuck SRQ state is terminated and the driver attempts a new set of serial polls Autopolling and Interrupts If autopolling and interrupts are both enabled the NI 488 2 software can perform autopolling after any device level NI 488 2 call provided that no GPIB I O is currently in progress In this case an automatic serial poll can Chapter 7 NI 488 2 Programming Techniques NI 488 2 User Manual for Windows 7 14 National Instruments Corporation occur even when your application is not making any calls to the NI 488 2 software Autopolling can also occur when a device level ibwait for RQS is in progress Autopolling is not allowed when an application calls a board level traditional or multi device NI 488 2 call or the stuck SRQ ESRQ condition occurs Note The NI
134. or Windows 6 4 National Instruments Corporation Once you successfully complete ibdev you have a ud prompt The new prompt ud0 represents a device level handle that you can use for further NI 488 2 calls To clear the device use ibclr as follows ud0 ibclr 0100 cmpl To write data to the device use ibwrt Make sure that you refer to the documentation that came with your GPIB instrument for specific command messages ud0 ibwrt enter string IDN 0100 cmpl count 5 Or equivalently ud0 ibwrt IDN 0100 cmpl count 5 To read data from your device use ibrd The data that is read from the instrument is displayed For example to read 29 bytes enter the following ud0 ibrd enter byte count 29 0100 cmpl count 29 46 4C 55 4B 45 2C 20 34 FLUKE 4 35 2C 20 34 37 39 30 31 5 47901 37 33 2C 20 31 2E 36 20 73 1 6 44 31 2E 30 0A D 10 Or equivalently ud0 ibrd 29 0100 cmpl count 29 46 4C 55 4B 45 2C 20 34 FLUKE 4 35 2C 20 34 37 39 30 31 5 47901 37 33 2C 20 31 2E 36 20 73 1 6 44 31 2E 30 0A D 10 Chapter 6 Interactive Control Utility National Instruments Corporation 6 5 NI 488 2 User Manual for Windows When you are finished communicating with the device make sure you put it offline using the ibonl command as follows ud0 ibonl 0 0100 cmpl The ibonl command properly closes the device handle and the ud0 prompt is no longer available Interactiv
135. plorer National Instruments Corporation 2 19 NI 488 2 User Manual for Windows Under Windows NT To enable NI 488 2 DOS support under Windows NT follow these steps 1 Open your config nt file located in the Windows NT system32 directory for example c windows system32 2 Find the following lines of code REM To run DOS GPIB applications uncomment the REM following line REM device lt path gt doswin16 gpib nt com where lt path gt is the directory in which you installed the NI 488 2 software 3 Remove REM from the last line so that it reads device lt path gt doswin16 gpib nt com To disable DOS support add REM back to the line of code where it was removed Access Additional Help and Resources for NI 488 2 and GPIB NI 488 2 Online Help The NI 488 2 online help includes information on getting started troubleshooting application development and answers to frequently asked questions as well as a complete NI 488 2 API function reference To view the NI 488 2 online help from Measurement amp Automation Explorer select a GPIB interface in the left window frame under Devices and Interfaces right click and choose NI 488 2 Help National Instruments GPIB Web Site To access the National Instruments web site for GPIB from Measurement amp Automation Explorer select the Measurement amp Automation icon then select Help National Instruments on the Web GPIB Home Page Chapter 2 Measurement
136. pplication National Instruments Corporation 3 13 NI 488 2 User Manual for Windows Language Specific Programming Instructions The following sections describe how to develop compile and link your Win32 NI 488 2 applications using various programming languages Microsoft Visual C C Version 2 0 or Later Before you compile your Win32 C application make sure that the following lines are included at the beginning of your program include lt windows h gt include decl 32 h To compile and link a Win32 console application named cprog in a DOS shell type the following on the command line cl cprog c gpib 32 obj Borland C C Version 4 0 or Later Before you compile your Win32 C application make sure that the following lines are included at the beginning of your program include lt windows h gt include decl 32 h To compile and link a Win32 console application named cprog in a DOS shell type the following on the command line bcc32 w32 cprog c borlandc_gpib 32 obj Visual Basic Version 4 0 or Later With Visual Basic you can access the traditional NI 488 2 calls as subroutines using the BASIC keyword CALL followed by the traditional NI 488 2 call name or you can access them using the il set of functions With some of the NI 488 2 calls for example ibrd and Receive the length of the string buffer is automatically calculated within the actual function or subroutine which eliminates the need to pass i
137. rate how to use direct entry to access gpib 32 dll For more information about direct entry refer to the online help that is built into your development environment Directly Accessing the gpib 32 dll Exports Make sure that the following lines are included at the beginning of your application ifdef __cplusplus extern C endif include lt windows h gt include decl 32 h ifdef __cplusplus endif In your Win32 application you need to load gpib 32 dll before accessing the gpib 32 dll exports The following code fragment shows you how to call the LoadLibrary function to load gpib 32 dll and check for an error HINSTANCE Gpib32Lib NULL Gpib32Lib LoadLibrary GPIB 32 DLL if Gpib32Lib NULL return FALSE The prototypes for each function can be found in the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces right click and choose NI 488 2 Help to view the online help For functions that return an integer value like ibdev or ibwrt the pointer to the function needs to be cast as follows int _stdcall Pname where Pname is the name of the pointer to the function For functions that do not return a value like FindLstn or SendList the pointer to the function needs to be cast as follows void _stdc
138. s if you have not already done so For help refer to the section Scan for GPIB Instruments 2 Select the GPIB interface listed under Devices and Interfaces in the left window frame of Measurement amp Automation Explorer 3 View the instrument information in the right window frame of Measurement amp Automation Explorer as shown in Figure 2 16 Chapter 2 Measurement amp Automation Explorer National Instruments Corporation 2 17 NI 488 2 User Manual for Windows Figure 2 16 GPIB Instrument Information The Name column displays the logical instrument name assigned by Measurement amp Automation Explorer The Type column display the instrument s response to the identification query IDN The Value column display the primary PAD and secondary SAD addresses of the instrument The Description column identifies the instrument as a GPIB instrument Change GPIB Device Templates For older NI 488 2 applications you might need to modify one of the device templates to find a given GPIB instrument by name for example ibfind fluke45 These older applications still use ibfind instead of the preferred ibdev NI 488 2 call to get a device handle New applications should avoid using ibfind to obtain device handles and use ibdev instead ibdev allows you to dynamically configure your GPIB Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 18 National Instrume
139. s and Interfaces in the left window frame right click and choose NI Spy as shown in Figure 4 1 Chapter 4 Debugging Your Application NI 488 2 User Manual for Windows 4 2 National Instruments Corporation Figure 4 1 Select NI Spy Global Status Variables At the end of each NI 488 2 call the global status variables ibsta iberr ibcnt and ibcntl are updated If you are developing an NI 488 2 application you should check for errors after each NI 488 2 call If a NI 488 2 call failed the high bit of ibsta the ERR bit is set For a failed NI 488 2 call iberr contains a value that defines the error In some error cases the value in ibcntl contains even more error information You can use NI Spy to determine which NI 488 2 call is failing Once you know which NI 488 2 call fails refer to Appendix B Status Word Conditions and Appendix C Error Codes and Solutions for help understanding why the NI 488 2 call failed This information is also available in the NI 488 2 online help available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Chapter 4 Debugging Your Application National Instruments Corporation 4 3 NI 488 2 User Manual for Windows Then select a GPIB interface under Devices and Interfaces right click and choose NI 488 2 Help to view the online help Existing Applications If the applicati
140. s general program steps with an NI 488 2 example Items to Include Include the following items in your application Header files In a C application include the header files windows h and decl 32 h The standard Windows header file windows h contains definitions used by decl 32 h and decl 32 h contains prototypes for the NI 488 2 calls and constants that you can use in your application Error checking Check for errors after each NI 488 2 call Chapter 3 Developing Your NI 488 2 Application National Instruments Corporation 3 11 NI 488 2 User Manual for Windows Error handling Declare and define a function to handle NI 488 2 errors This function takes the device offline and closes the application If the function is declared as void gpiberr char msg function prototype Then your application invokes it as follows if ibsta amp ERR gpiberr NI 488 2 error General Program Steps and Examples The following steps show you how to use the multi device NI 488 2 calls in your application The NI 488 2 software includes the source code for an example written in C 4882query c and the source code for the example written to use direct entry to access the gpib 32 dll dll4882query c The NI 488 2 software also includes a sample program written in Visual Basic query4882 frm Initialization Step 1 Become Controller In Charge CIC Use SendIFC to initialize the bus and the GPIB interfa
141. serts DIO5 when ist is 1 if a parallel poll is conducted ibppc 0 0x6C ibist 0 1 2 Conduct the parallel poll using ibrpp and check the response for a certain value The following example code performs the parallel poll and compares the response to hex 10 which corresponds to DIO5 If that bit is set the ist of the device is 1 ibrpp dev amp ppr if ppr amp 0x10 printf ist 1 n 3 Unconfigure the device for parallel polling with ibppc Notice that any value having the parallel poll disable bit set bit 4 in the bit pattern disables the configuration so you can use any value between hex 70 and 7E ibppc dev 0x70 Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation 7 19 NI 488 2 User Manual for Windows Parallel Polling with Multi Device NI 488 2 Calls Complete the following steps to implement parallel polling the using multi device NI 488 2 calls Each step contains example code 1 Configure the device for parallel polling using the PPollConfig routine unless the device can configure itself for parallel polling The following example configures a device at address 3 to assert data line 5 DIO5 when its ist value is 1 include decl 32 h char response Addr4882_t AddressList 2 The following command clears the GPIB SendIFC 0 The value of sense is compared with the ist bit of the device and determines whether the data line is asserted PPollConfig
142. stalled hardware and the GPIB interface should show up without any problems If the problem persists contact National Instruments Code 27 Windows was unable to assign the GPIB interface any resources To solve this problem free up system resources by disabling other unnecessary hardware so that enough resources are available for the GPIB interface Common Questions What do I do if my GPIB hardware is listed in the Windows Device Manager with a circled X or an exclamation point overlaid on it Refer to the Troubleshooting Device Manager Problems section of this appendix for specific information about what might cause this problem If you have already completed the troubleshooting steps contact National Instruments How can I determine which type of GPIB hardware I have installed Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB The Measurement amp Automation Explorer lists your installed GPIB hardware under Devices and Interfaces How can I determine which version of the NI 488 2 software I have installed Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Select Appendix D Windows 98 95 Troubleshooting and Common Questions NI 488 2 User Manual for Windows D 4 National Instruments Corporation Measurement amp Automation in the left window frame then choose Help About
143. te and the secondary address in the high byte If you are not using secondary addressing the secondary address is 0 For example if the primary address is 1 then the 16 bit value is 0x01 otherwise if the primary address is 1 and the secondary address is 0x67 then the 16 bit value is 0x6701 Step 3 Initialize the Devices Use DevClearList to clear the devices on the GPIB The first argument is the GPIB interface number The second argument is the list of GPIB addresses that were found to be listening as determined in Step 2 Device Communication Step 4 Communicate with the Devices Communicate with the devices by sending them the IDN query and then reading back the responses Many devices respond to this query by returning a description of the device Refer to the documentation that came with your GPIB devices to see specific instruction on the proper way to communicate with them Step 4a Use SendList to send the IDN query command to multiple GPIB devices The address is the list of GPIB devices to be queried The buffer that you pass to SendList is the command message to the device Step 4b Use Receive for each device to read the responses from each device Continue communicating with the GPIB devices until you are finished Cleanup Step 5 Place the Interface Offline before Exiting Your Application Use ibonl to put the interface offline before you exit the application Chapter 3 Developing Your NI 488 2 A
144. ted with NI 488 2 The NI 488 2 Getting Started Wizard helps you get started with GPIB instrument communication using Measurement amp Automation Explorer The general steps to get started with NI 488 2 are as follows 1 Install the NI 488 2 software and GPIB hardware by following the instructions on your Getting Started card If you do not have a Getting Started card select the View Documentation option from the NI 488 2 for Windows CD autorun screen as shown in Figure 2 2 Then select your operating system and GPIB interface Figure 2 2 Select View Documentation 2 Verify the installation and establish basic communication with your GPIB instruments using the NI 488 2 Getting Started Wizard To run the Getting Started Wizard select Measurement amp Automation in the left window frame of Measurement amp Automation Explorer then choose Help Getting Started NI 488 2 Getting Started Wizard as shown in Figure 2 3 Note The NI 488 2 Getting Started Wizard runs automatically after you install the NI 488 2 for Windows software and restart you system Chapter 2 Measurement amp Automation Explorer NI 488 2 User Manual for Windows 2 4 National Instruments Corporation Figure 2 3 Select Getting Started Wizard The Getting Started Wizard guides you through the process of verifying installation and establishing communication with your instrument Follow the steps outlined by the Getting Started Wizard by clicking on t
145. tility NI 488 2 User Manual for Windows 6 8 National Instruments Corporation ibwait mask Wait for selected event where mask is a hex or decimal integer or a list of mask bit mnemonics such as ibwait TIMO CMPL ibwrt wrtbuf Write data ibwrta wrtbuf Write data asynchronously ibwrtf flname Write data from a file where flname is pathname of file to write Table 6 2 Syntax for Board Level Traditional NI 488 2 Calls in Interactive Control Syntax Description ibask option Return configuration information where option is a mnemonic for a configuration parameter ibcac v Become active Controller ibcmd cmdbuf Send commands ibcmda cmdbuf Send commands asynchronously ibconfig option value Alter configurable parameters where option is mnemonic for a configuration parameter ibdma v Enable disable DMA ibeos v Change disable EOS message ibeot v Enable disable END message ibfind udname Return unit descriptor where udname is the symbolic name of interface for example gpib0 ibgts v Go from Active Controller to standby ibist v Set clear ist iblines Read the state of all GPIB control lines ibln pad sad Check for presence of device on the GPIB at pad sad ibloc Go to local ibonl v Place device online or offline ibpad v Change primary address Table 6 1 Syntax for Device Level Traditional NI 488 2 Calls in Interactive Control Continued Syntax Description Chapter 6 Interactive Control
146. tomatically prints to the screen This font also emphasizes lines of code that are different from the other examples Related Documentation The following documents contain information that you may find helpful as you read this manual ANSI IEEE Standard 488 1 1987 IEEE Standard Digital Interface for Programmable Instrumentation ANSI IEEE Standard 488 2 1992 IEEE Standard Codes Formats Protocols and Common Commands National Instruments Corporation 1 1 NI 488 2 User Manual for Windows 1 Introduction This chapter explains how to set up your GPIB system Setting up and Configuring Your System Devices are usually connected with a cable assembly consisting of a shielded 24 conductor cable with both a plug and receptacle connector at each end With this design you can link devices in a linear configuration a star configuration or a combination of the two configurations Figure 1 1 shows the linear and star configurations Figure 1 1 Linear and Star System Configuration Device A Device B Device C Device D Device A Device C Device B a Linear Configuration b Star Configuration Chapter 1 Introduction NI 488 2 User Manual for Windows 1 2 National Instruments Corporation Controlling More Than One Interface Figure 1 2 shows an example of a multiboard system configuration gpib0 is the access interface for the voltmeter and gpib1 is the access interface for the plotter and printer T
147. umentation xi related documentation xii DOS NI 488 2 applications enabling disabling support under Windows 98 95 2 18 under Windows NT 2 19 running under Windows 98 95 3 17 to 3 18 under Windows NT 3 18 DTAS status word condition bit position hex value and type table 3 7 description B 5 Talker Listener applications 7 12 E EABO error code C 5 EADR error code C 4 EARG error code C 4 EBUS error code C 7 to C 8 ECAP error code C 7 ECIC error code C 2 to C 3 EDMA error code C 6 EDVR error code description C 2 troubleshooting D 1 to D 2 EFSO error code C 7 e mail support F 1 Index NI 488 2 User Manual for Windows I 4 National Instruments Corporation END status word condition bit position hex value and type table 3 6 description B 2 end of string character See EOS ENEB error code C 5 to C 6 ENOL error code C 3 EOI end or identify line purpose table A 3 termination of data transfers 7 1 EOIP error code C 6 to 6 7 EOS configuring EOS mode 7 1 to 7 2 EOS comparison method 7 1 EOS read method 7 2 EOS write method 7 1 to 7 2 ERR status word condition bit position hex value and type table 3 6 description B 2 error codes and solutions debugging applications 4 3 EABO C 5 EADR C 4 EARG C 4 EBUS C 7 to C 8 ECAP C 7 ECIC C 2 to C 3 EDMA C 6 EDVR C 2 EFSO C 7 ENEB C 5 to C 6 ENOL C 3 EOIP C 6 to 6 7 ESAC C 5 ESRQ C 8 to C 9 ESTB C 8 ETAB C 9 GPIB
148. urns If you want to use ibwait to wait for one or more events to occur pass a wait mask to the function The wait mask should always include the TIMO event otherwise your application is suspended indefinitely until one of the wait mask events occurs Asynchronous Event Notification in Win32 NI 488 2 Applications Win32 NI 488 2 applications can asynchronously receive event notifications using the ibnotify function This function is useful if you want your application to be notified asynchronously about the occurrence of one or more GPIB events For example you might choose to use ibnotify if your application only needs to interact with your GPIB device when it is requesting service After calling ibnotify your application does not need to check the status of your GPIB device Then when your GPIB device requests service the NI 488 2 driver automatically notifies your application that the event has occurred by invoking a callback function The callback function is registered with the NI 488 2 driver when the ibnotify call is made Calling the ibnotify Function ibnotify has the following function prototype ibnotify int ud unit descriptor int mask bit mask of GPIB events GpibNotifyCallback_t Callback callback function void RefData user defined reference data Both board level and device level ibnotify calls are supported by the NI 488 2 driver If you are using device level calls you call ibnotify with a device han
149. valid unit descriptor is passed to any traditional NI 488 2 call Solutions Possible solutions for this error are as follows Use ibdev to open a device without specifying its symbolic name Use only device or interface names that are configured in the NI 488 2 Configuration utility as parameters to the ibfind function Use the NI 488 2 Troubleshooting Wizard to ensure that each interface you want to access is working properly To start the NI 488 2 Troubleshooting Wizard first open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB Then select Measurement amp Automation in the left window frame and choose Help Troubleshooting NI 488 2 Troubleshooting Wizard Use the unit descriptor returned from ibdev or ibfind as the first parameter in subsequent traditional NI 488 2 calls Examine the variable before the failing function to make sure its value has not been corrupted Refer to the NI 488 2 online help for the NI 488 2 software available through Measurement amp Automation Explorer To start Measurement amp Automation Explorer select Start Programs National Instruments NI 488 2 Explore GPIB Then select a GPIB interface under Devices and Interfaces in the left window frame right click and select NI 488 2 Help to view the online help ECIC 1 ECIC is returned when one of the following board functions or routines is called while
150. ver 3 3 NI 488 2 Language Interfaces 3 4 Direct Entry Access 3 4 Choosing How to Use the NI 488 2 API 3 4 Communicating with a Single GPIB Device 3 4 Using Multiple Interfaces and or Multiple Devices 3 5 Checking Status with Global Variables 3 6 Status Word ibsta 3 6 Error Variable iberr 3 7 Count Variables ibcnt and ibcntl 3 8 Using Interactive Control to Communicate with Devices 3 8 Programming Models 3 8 Applications That Communicate with a Single GPIB Device 3 8 Items to Include 3 8 General Program Steps and Examples 3 9 Applications That Use Multiple Interfaces or
151. vices use the multi device NI 488 2 calls Whichever option you choose bus management operations necessary for device communication are performed automatically The following sections describe some differences between the traditional NI 488 2 calls and the multi device NI 488 2 calls Communicating with a Single GPIB Device If your system has only one device attached to each interface the traditional NI 488 2 calls are probably sufficient for your programming needs A typical NI 488 2 application with a single device has three phases Initialization use ibdev to get a handle and use ibclr to clear the device Device Communication use ibwrt ibrd ibtrg ibrsp and ibwait to communicate with the device Cleanup use ibonl to put the handle offline Refer to the sample applications that are installed with the NI 488 2 software to see detailed examples for different GPIB device types Chapter 3 Developing Your NI 488 2 Application National Instruments Corporation 3 5 NI 488 2 User Manual for Windows For NI 488 2 applications that need to control the GPIB in non typical ways for example to communicate with non compliant GPIB devices there are a set of low level functions that perform rudimentary GPIB applications If you use these functions you need to understand GPIB management details like how to address talkers and listeners Refer to Appendix A GPIB Basics for some details on GPIB management The s
152. with C 3 14 to 3 17 directly accessing gpib 32 dll exports 3 15 to 3 17 gpib 32 dll exports 3 14 to 3 15 Microsoft Visual Basic 3 13 to 3 14 Microsoft Visual C C 3 13 multiple interfaces or multiple GPIB devices becoming Controller In Charge 3 11 communicating with devices 3 12 determining GPIB address of device 3 11 to 3 12 general steps and examples 3 11 to 3 13 initialization 3 11 to 3 12 initializing devices 3 12 items to include 3 10 to 3 11 placing device offline 3 13 NI 488 2 API 3 4 to 3 5 communicating with one GPIB device 3 4 to 3 5 low level functions 3 5 multiple interfaces and or multiple devices 3 5 overview 3 4 applications existing See existing applications asynchronous event notification in Win32 applications 7 4 to 7 9 calling ibnotify function 7 4 to 7 5 ibnotify programming example 7 5 to 7 9 Index NI 488 2 User Manual for Windows I 2 National Instruments Corporation ATN attention line table A 3 ATN status word condition bit position hex value and type table 3 7 description B 4 automatic serial polling See serial polling auxiliary functions Interactive Control table 6 11 B Borland C C 3 13 buffer option function Interactive Control 6 11 C C language direct entry for application development 3 14 to 3 17 directly accessing gpib 32 dll exports 3 15 to 3 17 gpib 32 dll exports 3 14 to 3 15 cable length for high speed data transfers 7 2 7 3
153. y NI 488 2 application Examine the value of ibsta after each NI 488 2 call If a call fails the ERR bit of ibsta is set and an error code is stored in iberr For more information about global status variables refer to Chapter 4 Debugging Your Application What information should I have before I call National Instruments When you call National Instruments you should have the results of the NI 488 2 Troubleshooting Wizard Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB From there select Measurement amp Automation in the left window frame then choose Help Troubleshooting NI 488 2 Troubleshooting Wizard National Instruments Corporation F 1 NI 488 2 User Manual for Windows F Technical Support Resources National Instruments offers technical support through electronic fax and telephone systems The electronic services include our Web site an FTP site and a fax on demand system If you have a hardware or software problem please first try the electronic support systems If the information available on these systems does not answer your questions contact one of our technical support centers which are staffed by applications engineers for support by telephone and fax To comment on the documentation supplied with our products send e mail to techpubs natinst com Web Site The InstrumentationWeb address is http www natinst com From this Web sit
154. yntax in Interactive Control 6 5 O online help for NI Spy 5 3 P parallel polling 7 17 to 7 19 implementing 7 17 to 7 19 using multi device NI 488 2 calls 7 19 using traditional NI 488 2 calls 7 17 to 7 18 PPoll routine 7 19 PPollConfig routine 7 19 PPollUnconfig routine 7 19 primary GPIB address A 2 problem solving See debugging troubleshooting and common questions programming See application development debugging NI 488 2 API Q q function Interactive Control 6 11 R ReadStatusByte routine 7 15 Receive routine example 3 12 REM status word condition bit position hex value and type table 3 7 description B 4 REN remote enable line table A 3 repeat addressing 4 5 repeat previous function function Interactive Control 6 11 RQS status word condition bit position hex value and type table 3 7 description B 3 running existing applications See existing applications S scanning for GPIB instruments 2 6 to 2 7 secondary GPIB address A 2 SendIFC routine becoming Controller in Charge example 3 11 using in Interactive Control example 6 3 Index NI 488 2 User Manual for Windows I 10 National Instruments Corporation SendList routine example 3 12 serial polling 7 12 to 7 16 automatic serial polling 7 13 to 7 14 autopolling and interrupts 7 13 to 7 14 stuck SRQ state 7 13 service requests from IEEE 488 devices 7 12 from IEEE 488 2 devices 7 12 SR
155. ypically set to 1 so that EOI is asserted with the last byte of writes EOS detection mode typically 0 if the GPIB instrument does not use EOS characters A successful ibdev call returns a device handle ud that is used for all device level traditional NI 488 2 calls that communicate with the GPIB instrument Chapter 3 Developing Your NI 488 2 Application NI 488 2 User Manual for Windows 3 10 National Instruments Corporation Step 2 Clear the Device Use ibclr to clear the device This resets the device s internal functions to the default state Device Communication Step 3 Communicate with the Device Communicate with the device by sending it the IDN query and then reading back the response Many devices respond to this query by returning a description of the device Refer to the documentation that came with your GPIB device to see specific instructions on the proper way to communicate with it Step 3a Use ibwrt to send the IDN query command to the device Step 3b Use ibrd to read the response from the device Continue communicating with the GPIB device until you are finished Cleanup Step 4 Place the Device Offline before Exiting Your Application Use ibonl to put the device handle offline before you exit the application Applications That Use Multiple Interfaces or Communicate with Multiple GPIB Devices This section describes items you should include in your application and provide
156. ystem configuration Are interrupts and DMA required for the NI 488 2 software Neither interrupts nor DMA are required under Window 98 95 unless you are using a PCMCIA GPIB or GPIB hardware with Analyzer capability in which case at least one interrupt level is required Appendix D Windows 98 95 Troubleshooting and Common Questions National Instruments Corporation D 5 NI 488 2 User Manual for Windows How can I determine if my GPIB hardware and NI 488 2 software are installed properly Run the NI 488 2 Troubleshooting Wizard to make sure that your hardware and software are correctly installed Open Measurement amp Automation Explorer by selecting Start Programs National Instruments NI 488 2 Explore GPIB From there select Measurement amp Automation in the left window frame then choose Help Troubleshooting NI 488 2 Troubleshooting Wizard When should I use the Interactive Control utility You can use the Interactive Control utility to test and verify instrument communication troubleshoot problems and develop your application For more information refer to Chapter 6 Interactive Control Utility How do I use an NI 488 2 language interface For information about using NI 488 2 language interfaces refer to Chapter 3 Developing Your NI 488 2 Application What do I need to know to communicate properly with my GPIB instrument Refer to the documentation that came from the instrument manufacturer The command
157. yte is read in or the EOI line is asserted during a read High Speed Data Transfers HS488 National Instruments has designed a high speed data transfer protocol for IEEE 488 called HS488 This protocol increases performance for GPIB reads and writes up to 8 Mbytes s depending on your system HS488 is a superset of the IEEE 488 standard thus you can mix IEEE 488 1 IEEE 488 2 and HS488 devices in the same system If HS488 is enabled the TNT4882C hardware implements high speed transfers automatically when communicating with HS488 instruments If you attempt to enable HS488 on a GPIB interface that does not have the TNT4882C hardware the ECAP error code is returned Enabling HS488 To enable HS488 for your GPIB interface use the ibconfig function option IbcHSCableLength The value passed to ibconfig should specify the number of meters of cable in your GPIB configuration If you specify a cable length that is much smaller than what you actually use the transferred data could become corrupted If you specify a cable length longer than what you actually use the data is transferred successfully but more slowly than if you specified the correct cable length In addition to using ibconfig to configure your GPIB interface for HS488 the Controller In Charge must send out GPIB command bytes interface messages to configure other devices for HS488 transfers Chapter 7 NI 488 2 Programming Techniques National Instruments Corporation

NI-488.2 User Manual for Windows

Contents

Download Pdf Manuals

Related Search

Related Contents