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Chapter 4
Reconfiguring the NI-488.2M Software
Several applications require customized configuration of the GPIB 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 use either
the ibconf utility to permanently reconfigure the driver, or you can use the
dynamic configuration function call ibconfig to modify the driver while
your application is running.
ibconfig does not permanently change the state of the driver. Using
dynamic configuration automatically configures the driver as necessary.
Note:
To change settings other than base I/O address, interrupt level, or
DMA channel, National Instruments recommends using ibconfig
instead of running the ibconf utility.
If your program uses dynamic configuration, it will always work regardless of
the previous driver configuration. For more information, refer to the description
of ibconfig in the NI-488.2M Function Reference Manual for OS/2.
Timing Errors
If your application fails but the same calls issued in ibic 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.
A well-behaved IEEE 488 device should hold off handshaking and set the
appropriate transfer rate. 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 GPIB call. One way to perform this action
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 will be controlled by the device and your application can adjust itself and
work independently on any platform. Other delay mechanisms will probably
cause varying delay times on different platforms.
© National Instruments Corp.
Debugging Your Application
4-5
NI-488.2M SRM for OS/2
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