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National Instruments NI-488.2 SRQ and Serial Polling with NI-488 Device Functions

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Chapter 7 GPIB Programming Techniques

© National Instruments Corp. 7-7 NI-488.2 User Manual for Windows

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 call as long as no GPIB I/O is currently in

progress. This means that an automatic serial poll can 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 whenever an

application calls a board-level NI-488 function or any NI-488.2 routine, or the stuck SRQ

(ESRQ) condition occurs.

If autopolling is enabled and interrupts are disabled, you can use autopolling in the

following situations only:

• During a device-level ibwait for RQS

• Immediately after a device-level NI-488 function is completed, before control is

returned to the application program

SRQ and Serial Polling with NI-488 Device Functions

You can use the device-level NI-488 function ibrsp to conduct a serial poll. ibrsp

conducts a single serial poll and returns the serial poll response byte to the application

program. If automatic serial polling is enabled, the application program 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 illustrates the use of the ibwait and ibrsp functions in a

typical SRQ servicing situation when automatic serial polling is enabled.

#include "decl.h"

char GetSerialPollResponse ( int DeviceHandle )

{

char SerialPollResponse = 0;

ibwait ( DeviceHandle, TIMO | RQS );

Contents

Main Page Limited Warranty Copyright Trademarks WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS Contents About This Manual Chapter One Introduction Chapter 2 Application Examples Chapter 3 Developing Your Application Chapter 4 Debugging Your Application Chapter 5 wibicWindows Interface Bus Interactive Control Utility Chapter 6 GPIB Spy Chapter 7 GPIB Programming Techniques Chapter 8 wibconfWindows Interface Bus Configuration Utility Page Tables About This Manual How to Use This Manual Set Organization of This Manual Conventions Used in This Manual italic monospace Related Documentation Customer Communication Chapter 1 Introduction GPIB Overview Talkers, Listeners, and Controllers Controller-In-Charge and System Controller GPIB Addressing Sending Messages Across the GPIB Page Setting Up and Configuring Your System Configuration Requirements The NI-488.2 Software Package NI-488.2 Driver and Driver Utilities C Language Files Visual Basic Language Files Win 32s Files Sample Application Files How the NI-488.2 Software Works with Windows Windows Unloading and Reloading the NI-488.2 Driver Chapter 2 Application Examples Example 1: Basic Communication National Instruments Corp. 2-3 NI-488.2 User Manual for Windows Figure 2-1. Program Flowchart for Example 1 Example 2: Clearing and Triggering Devices National Instruments Corp. 2-5 NI-488.2 User Manual for Windows Figure 2-2. Program Flowchart for Example 2 Example 3: Asynchronous I/O National Instruments Corp. 2-7 NI-488.2 User Manual for Windows Figure 2-3. Program Flowchart for Example 3 Example 4: End-of-String Mode National Instruments Corp. 2-9 NI-488.2 User Manual for Windows Figure 2-4. Program Flowchart for Example 4 Example 5: Service Requests Page Application Examples Chapter 2 NI-488.2 User Manual for Windows 2-12 National Instruments Corp. (continues) Figure 2-5. Program Flowchart for Example 5 National Instruments Corp. 2-13 NI-488.2 User Manual for Windows (Continued) Figure 2-5. Program Flowchart for Example 5 (Continued) Example 6: Basic Communication with IEEE 488.2-Compliant Devices National Instruments Corp. 2-15 NI-488.2 User Manual for Windows Figure 2-6. Program Flowchart for Example 6 Example 7: Serial Polls Using NI-488.2 Routines National Instruments Corp. 2-17 NI-488.2 User Manual for Windows SendList Figure 2-7. Program Flowchart for Example 7 "SRQ=HI" WaitSRQ FindRQS Example 8: Parallel Polls National Instruments Corp. 2-19 NI-488.2 User Manual for Windows Figure 2-8. Program Flowchart for Example 8 Example 9: Non-Controller Example National Instruments Corp. 2-21 NI-488.2 User Manual for Windows fffffffffff Figure 2-9. Program Flowchart for Example 9 Chapter 3 Developing Your Application Choosing How to Access the NI-488.2 DLL Choosing Between NI-488 Functions and NI-488.2 Routines Using NI-488 Functions: One Device for Each Board Using NI-488.2 Routines: Multiple Boards and/or Multiple Devices Checking Status with Global Variables Status Word ibsta Page Error Variable iberr Count Variables ibcnt and ibcntl Using wibic to Communicate with Devices Writing Your NI-488 Application Items to Include Chapter 3 Developing Your Application National Instruments Corp. 3-7 NI-488.2 User Manual for Windows NI-488 Program Shell Figure 3-1. General Program Shell Using NI-488 Device Functions General Program Steps and Examples Page Page Writing Your NI-488.2 Application Items to Include Developing Your Application Chapter 3 NI-488.2 User Manual for Windows 3-12 National Instruments Corp. NI-488.2 Program Shell Figure 3-2. General Program Shell Using NI-488.2 Routines Figure 3-2 is a flowchart of the steps to create your application program using NI-488.2 routines. General Program Steps and Examples Page Page Page Compiling, Linking, and Running Your Application Microsoft C Borland C++ Visual Basic Direct Entry with C Page Page Page Page Direct Entry with Visual Basic Chapter 4 Debugging Your Application Running wibtest gpibx x Presence Test of Driver Running GPIBInfo Debugging with the Global Status Variables Debugging with wibic Debugging with GPIB Spy GPIB Error Codes Configuration Errors Timing Errors Communication Errors Repeat Addressing Termination Method Common Questions Page Page Chapter 5 wibicWindows Interface Bus Interactive Control Utility Example Using NI-488 Functions Page Page wibic Syntax Number Syntax String Syntax Address Syntax wibic Syntax for NI-488 Functions Page Page wibic Syntax for NI-488.2 Routines Status Word Error Information Count Common NI-488 Functions ibfind ibdev Page ibwrt ibrd Common NI-488.2 Routines in wibic Set Send and SendList Receive Auxiliary Functions Set (Select Device or Board) Help (Display Help Information) ! (Repeat Previous Function) - (Turn Display Off) and + (Turn Display On) n* (Repeat Function n Times) $ (Execute Indirect File) Print (Display the ASCII String) Buffer (Set Buffer Display Mode) Chapter 6 GPIB Spy Starting GPIB Spy Exiting GPIB Spy Viewing Call Details GPIB Spy Configuration Options Calls To Highlight Calls To Trap On Buffer History Set Highlight Color GPIB Spy Output Options To Screen To File Clear Screen GPIB Spy Help Performance Considerations Chapter 7 GPIB Programming Techniques Termination of Data Transfers High-Speed Data Transfers (HS488) Enabling HS488 System Configuration Effects on HS488 Waiting for GPIB Conditions Device-Level Calls and Bus Management Talker/Listener Applications Waiting for Messages from the Controller Using the Event Queue Requesting Service Serial Polling Service Requests from IEEE 488 Devices Service Requests from IEEE 488.2 Devices Automatic Serial Polling SRQ and Serial Polling with NI-488 Device Functions SRQ and Serial Polling with NI-488.2 Routines Page Parallel Polling Implementing a Parallel Poll Page Page Chapter 8 wibconfWindows Interface Bus Configuration Utility Starting wibconf driver Upper and Lower Levels of wibconf Upper-Level Device Map Page Lower-Level Device/Board Characteristics Page Board and Device Configuration Options Primary GPIB Address Secondary GPIB Address Timeout Setting Page Send EOI at End of Write System Controller (Board Characteristic Only) Assert REN when SC (Board Characteristic Only) Enable Auto Serial Polling (Board Characteristic Only) Enable CIC Protocol (Board Characteristic Only) Bus Timing (Board Characteristic Only) Cable Length for High Speed (Board Characteristic Only) Parallel Poll Duration (Board Characteristic Only) Use This GPIB Interface (Board Characteristic Only) Base I/O Address (Board Description Only) DMA Channel (Board Characteristic Only) Interrupt Jumper Setting (Board Characteristic Only) Enable Repeat Addressing (Device Characteristic Only) GPIB-PCII/IIA Mode Switch Default Configurations in wibconf Exiting wibconf Checking for Errors wibconf Batch Mode Page Page Appendix A Status Word Conditions ERR (dev, brd) TIMO (dev, brd) END (dev, brd) SRQI (brd) RQS (dev) SPOLL (brd) EVENT (brd) CMPL (dev, brd) LOK (brd) REM (brd) CIC (brd) ATN (brd) TACS (brd) LACS (brd) DTAS (brd) DCAS (brd) Appendix B Error Codes and Solutions EDVR (0) ECIC (1) ENOL (2) EADR (3) EARG (4) ESAC (5) EABO (6) ENEB (7) EDMA (8) drive path EOIP (10) ECAP (11) EFSO (12) EBUS (14) ESTB (15) ESRQ (16) ETAB (20) Appendix C Customer Communication Technical Support Form Page Documentation Comment Form Page Glossary A B C D E G H I K L M N P R S T U W Index Symbols A Page B C D E Page Page F G H I L M N O P R S T V W