GPIB error in the instrument while no communication error

Question

I am developing a test system by connecting several measurement instruments through GPIB with LabVIEW 6.i. The driver is written by using VISA command. GPIB control card is NI PCMCIA. When using laptop everything runs fine. When using an old PC with something like EISA to PCI converting card for slotting in the NI PCMCIA card. One instrument always displays an GPIB error. The error is instrument specific, no further detail is given by the manual. When the error comes out, no GPIB or VISA error exists. If only the driver for this instrument is installed so that the software only communicates with this particular instrument, no error. With other driver installed, there is no error in the first or two commnunication
. Later on the error is surely out and display in the instrument screen only. Once again, no any other GPIB or VISA communication error. Anybody can help on this ? Thanks a lot.

Answer 1

Hi JLS,
First of all, thank you very much for your prompt response. I am not sure some of your questions because our hardware engineer is away for a week. I am trying to explain what I know and see whether you could help to figure out the reason.
0. The operation system in the old PC is Win98. The CPU is PII 350MHz, 32G Hard disk and 320M RAM. The reason why we are using the old PC is that we have a 3rd party motion controller. Its control card is a ISA card.
1. The conversion device is a kind of card, put in the ISA slot in the PC extention I/O bus. We can slot in 2 PCMCIA cards in the conversion device. The driver for the NI PCMCIA card is supposed to be the same with that in laptop.
2. The driver that works with the instrument is developed by me by using NI-VISA. The instrument is a signal generator (SG) from Marconi instruments. Basically what the driver does is to turn on or turn off SG and read back its on-off status. When turning on SG, send setting frequency and signal level data as well. The calling of the driver is in a loop where frequency is stepping up.
3. There are other measuring instruments. e.g. electric field monitor probe to get the electric field strength etc. All these instruments' driver are developed by me by using NI-VISA. I also develop a set of dummy driver for all the instrument for demo purpose. Dummy drive did not communicate with instrument, inside, control is directly wired to status. When all other instruments except SG uses dummy driver, The running is OK. No error is displayed in the SG screen. If I use any of the other instrument's driver with that of SG, there is no problem at the first run (that means at the beginning of the loop), problem surely comes out later on. But it is OK when running in the laptop of which the OS is Win2000. The funny thing is if I takes out the status readback in SG driver, there will be no error at all even running with other instruments' driver in the old PC. I have compare through the GPIB card setting in the old PC and laptop, make sure that the EOI setting, primary address, EOS etc. to be the same in the two computer. It does not work.
4 & 5. The error displayed in the instrument screen is Error#403 "Data Expected". The manual said it is caused by the GPIB programming wrongly. No further explaination on how it may happen. Even there is such error display, no any GPIB or VISA error happens in my driver, the error cluster is clear. I debug the problem and find that the SG error appears when executing VISA resource open. I have also checked through all the NI GPIB help. It seems I could not find the answer.
6. I am not sure how to check the version of NI-488.2 and NI-VISA. NI-VISA is installed with the LabVIEW 6.i together.
Best Regards
Jason