GPIB control through applications not working

[RenaeTM]

Hello,

On a fresh windows 10 installation, version 1909, I'm having trouble with my GPIB-USB-HS not controlling several pieces of equipment (agilent 6623, 81110, r&s sml01). I'm using older scripts (unable to modify this legacy code) written in python 2.3 and a vb gui to control the equipment over GPIB. I'm getting errors when trying to read or write to the equipment. However, NI MAX is able to see the equipment and I'm able to manually send queries and writes that are working. 

On a second machine with the same configuration, but hasn't been updated yet, windows 10 version 1809, I am able to use everything just fine.

Any suggestions on anything to try that may be blocking use of the GPIB bus by 3rd party applications? I'm at a complete loss.

We have tried installing and reinstalling the older 488.2 version that's on the second computer as well as trying the latest 488.2 version. We've disabled firewalls, app lockers, and anti-virus. We've checked a ridiculous amount of group policies and compared them between machines to look for differences.

I'm desperate to try anything to get this to work. 

[santo_13]

Since NI MAX can discover the instruments correctly, that means no issue with 488.2 driver. What kind of error? what kind of operations work?

May be look into termination character settings and stuff?

[mkossmann]

Does it allready fail when opening the instrument ? Or does it fail on some random command ? 

You might try to log your scripts with NI-IOTrace on both PCs and compare these logs. 

[RenaeTM · Accepted solution]

The problem ended up being that there were two gpib devices in the computer - a PCI GPIB and a GPIB-USB-HS. I was using the USB without problems until the update. After the update, it seems that since the pci card was listed as device 0, my scripts and applications must have been attempting to use that device over the usb (which is what was actually connected to the instruments). Regardless of why, using the PCI GPIB caused instrument control to function again. Removing the PCI GPIB and using the USB also works.