I have a conflict between two GPIB instruments.

[Andy Goddard]

I have two old GPIB (488) compatible instruments, one lacking in instruction books (a LAS LDL 205 dye laser) and a SRS computer interface module. I am using a NI PCI-GPIB (488.2) card in my PC. I have managed to write a Labview driver for each device, and they work independently. But if both devices are connected then only the laser (the one with least available information!) works and the boxcar communicator cannot communicate. These devices have different addresses assigned. Eventually the boxcar device times out. I have changed the connecting cables, changed the boxcar address and even swapped the affected instrument for a similar one, but to no avail. Any suggestions welcome.

[Ray K]

Try communicating via IBIC when both devices are hooked up.

If also could be a problem with your cabling. 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(if your devices are not 488.2 compliant these guidelines might be stricter):
• 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 or controllers connected to each bus,
with at least two-thirds powered on.

Ray K
NI Applications Engineer