It could be the card, I'm obviously not an expert on MC's GPIB cards. An error like this at a GPIB write would make me think that the GPIB card addressed the device to listen and itself to talk, but for some reason the GPIB bus/instrument responded incorrectly or the card responded incorrectly to the commands that were sent to it. Since it seems sporadic, perhaps it could be timing or a questionable cable.
If you suspect that it may be the GPIB card, your sales rep would be more than happy to find a loaner NI PCI-GPIB card for you. If you do not know your sales representative, you can call 800-433-3488 to get in touch with them. Scott B. Applications Engineer National Instruments
