Communication Errors; Repeat Addressing; Termination Method - National Instruments NI-488.2M Software Reference Manual

Debugging Your Application Chapter 4

Communication Errors

Repeat Addressing

Some devices require GPIB addressing before any GPIB activity. 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. You might
need to configure your NI-488.2M driver to perform repeat addressing if your
device does not remain in its currently addressed state. Refer to Chapter 7,
ibconf—Interface Bus Configuration Utility, or to the description of ibconfig
in the NI-488.2M Function Reference Manual for OS/2 for more information
about reconfiguring your software.

Termination Method

You should be aware of the termination method that your device uses. By
default, your NI-488.2M 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 the device does not respond, it may not recognize the end of
the command. You may need to send a termination message, such as <CR>
<LF>, after a write command, as follows:
ibwrt(dev,"COMMAND\x0A\x0D",9);
NI-488.2M SRM for OS/2 4-6 © National Instruments Corp.