viRead timeout error using VISA with NI GPIB board

[BruceH]

I have a program written in VB 6 several years ago which will talk to a GPIB device using VISA. It has always worked fine. Now we have a situation where we have an NI PCI-GPIB board on an Windows XP machine where viRead often results in a timeout error. If I send the same query multiple times eventually I get a response from the device using the exact same viRead code. To make this even stranger if NI Spy is running the problem goes away and there a no timeout errors at all. This tells me there is not likely any problem with the GPIB device I am sending the query to but there is a some issue with my NI software. What could NI Spy be doing to make it work? Why doesn't it work with this setup but has worked previously? Nothing has been changed in the source code. The only difference is this is on another operating system with newer versions of NI software.

I found another article with someone having a similar strange issue where NI Spy resolved it :

http://forums.ni.com/ni/board/message?board.id=180&message.id=12773&requireLogin=False

We have the following hardware and software installed on the machine in question:
PCI-GPIB board
NI-488.2 ver 2.10
NI SPY ver 2.1.0.12
VISA32.DLL ver 3.2.0.19
Measurement & Automation Explorer Ver 3.1.0.3021

[Cyril]

Hi,

You may want to check this KB out:
GPIB Timeout Errors (EABO) after Updating to Faster Computers

Running NI-Spy in the background actually slows down the communication on the GPIB bus, so I strongly suspect that what's explained above is what you're experiemcing.

Hope this helps,

[BruceH]

Cyril,
Thank you for your post. I think you may be on to something. I have added the delays but will not be able to have it tested until Monday because the device is in another location. I'll post the results then.

Bruce

[BruceH]

Cyril,
We tried the GPIB device with at 75 ms delay inserted before every GPIB read or write. It worked fine. So it looks like you are right, the GPIB device is not working properly with the newer faster computer. My company makes the GPIB device and we are using at TMS9914 GPIB chip. This is an old device and up until now we did not know there was anything wrong. It seems like the TMS9914 should prevent commands from being sent from the GPIB master if it is not ready.

Thanks for your help on this.

Bruce