issue talking with 2 devices connected via GPIB

[markanddave]

We installed a PCI-GPIB, with NI-488.2, in a windows XP machine with the latest drivers 2.7.3. The install went fine. We have two pieces of gear connected; under Measurement & Automation Explorer we can query the (Solartron 1252A, Frequency Response Analyzer) which is on address  4, and it will respond to the ident command, and the other (Solartron 1287, Potentiostat) on address 2 which will not respond to a query.
Now here is where it gets weird under the two software programs (Corrware and Zplot) that we use these instruments with we can talk with the 1287 just fine, but we can’t talk with the 1252A which is the one that will query in explorer? I have found a temporary solution to this, when I open NI Spy and hit run, we can talk with the 1252A just fine but ONLY while NI Spy in running? We had this setup working perfectly since January, but just now had to swap out the PC, so the address and all cables are in the exact configuration as before. The only thing that has changed is the PC. NI-488.2 Troubleshooting Utility shows a pass on the software and hardware.

Any suggestions would be greatly appreciated,

-Mark

[Albert.Geven]

The solartron is quite slow on the bus. Please change the busspeed to 2u seconds.

Also the use of spy points to this slowness

[markanddave]

Tried this before and did not work. Tried it again and still does not seem to work. Any other suggestions?

Thanks

-Mark

[Albert.Geven]

The only other thing I can think of is to uncheck autopolling but see no direct proof for that.

The busspeed and good cabling should be enough.

How long is your cable and what kind of cable are you using?

Also how many powered off devices are on the bus ( I believe at most 2 in your case)

[markanddave]

Well didnt work either with Autopolling on or off. The cabling works fine when the NI spy is on, so I would not think the cabling is an issue. The cable is about 1 meter. Not exactly sure on the cable specifics, but it is made by NI and seems like a standard IEEE-488 cable.

[markanddave]

Oh forgot to reply about the powered off devices. I was not sure what this meant. But I see that I have two instruments that communicate on addresses 2 and 4 and 2 more available instruments on addresses 3 and 5 which are not in use.

[Dennis_Knutson]

Very, very big item to forget to mention. The GPIB specification requires at least two thirds of the instruments be powered. Turn them on or disconnect them so you have the proper loading of the bus.

[markanddave]

Could you explain more about turning on/off the instruments. I have only 2 GPIB cables connected to the pci card and when I scan for instruments I always seem to get 4 available addresses (usually 2 through 5). I can not seem to delete one of these instruments after the Scan for Instruments. Thanks so much for explaination!

[Dennis_Knutson]

I don't see how you can have 4 separate instruments, two of which are turned off, not connected, and yet have MAX report 4. What are the makes and models of all the instruments?

[markanddave]

Both instruments are made by Solartron. One is a Frequency Response Analyzer, model 1252A. The other is a potentiostat/galvanostat, model 1287 also called an electrochemical interface.