Autopolling And Interrupts; Srq And Serial Polling With Device-Level Traditional Ni-488.2 Calls - National Instruments NI-488.2 User Manual

Chapter 7 NI-488.2 Programming Techniques

SRQ and Serial Polling with Device-Level Traditional NI-488.2 Calls

NI-488.2 User Manual for Windows

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
occur even when your application is not making any calls to the NI-488.2
software. Autopolling can also occur when a device-level
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.
Windows 98/95
In Windows 98/95, you can use your GPIB interface without interrupts, but
the NI-488.2 software performance is significantly slower without
interrupts. For example, transfer sizes between 1 and 10 bytes transfer at a
rate of only 2% of the transfer rate with enabled interrupts. As the transfer
size increases, the performance degradation decreases slightly, but it
remains a significant problem for all transfers under 1 Mbyte. For
instructions on how to assign an interrupt to your GPIB interface if one was
not assigned, refer to the
Windows 98/95: Troubleshooting and Common
Windows 2000/NT
The NI-488.2 software for Windows 2000/NT does not function properly
if interrupts are disabled.
You can use the device-level traditional NI-488.2 call
serial poll. conducts a single serial poll and returns the serial poll
ibrsp
response byte to the application. If automatic serial polling is enabled, the
application can use
ibwait
appears in the status word,
obtain the serial poll response byte.
The following example shows you how to use the
functions in a typical SRQ servicing situation when automatic serial polling
is enabled:
#include "decl-32.h"
char GetSerialPollResponse ( int DeviceHandle )
{
Enabling Interrupts
to suspend program execution until RQS
. The program can then call
ibsta
7-14
for RQS
ibwait
section in Appendix D,
Questions.
to conduct a
ibrsp
ibrsp
and
ibwait ibrsp
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