GPIB Duplicate Path: New I/O Attempted with old I/O in progress.

[MicTomReiSr]

I am getting a GPIB I/O error and am not sure why. Appreciate any assistance. I am controlling two identical test units on one bus line. Each unit consists of three instruments. The addresses for unit 1 are 5, 1, and 10. The addresses for unit two are 6, 3, and 11. The GPIB bus line is through a PCI GPIB card. The error is "NI-488: New I/O Attempted with old I/O in progress". Shouldn't the PCI GPIB card automatically handle this type of synchronization issues? Perhaps this is not the issue at all. A troubling aspect is that the same software and hardware function seamlessly on another identical PC and dual-test setup.

[MicTomReiSr]

Could this be related to sending commands synchronously versus asynchronously? I changed my command flow to Synchronous (right click on the GPIB command VIs and select Sync.) but have yet attempted to test it.

[John E]

Hi Mike,
You are welcome to try changing the command flow to Syncronous however I doubt that will resolve the issue.  I would recommend looking at what are the differences if the 2 setups.  You can also run NI-SPY on both machines and find out where the error is occurring.  Also the following links may be useful to you.

Error 10
http://digital.ni.com/public.nsf/websearch/E185E6BE180AC660862568EA0080DF3E#EOIP

http://digital.ni.com/public.nsf/websearch/E185E6BE180AC660862568EA0080DF3E#EOIP

Regards,

[MicTomReiSr]

Changing asunch to synch did it. (Right click on the GPIB VI's and select Synchronous mode) The key difference between the two stations was the GPIB controller card. In the station that worked fine, the controller was an ethernet-based controller (part number unknown as I write this) and the other one had a PCI-based GPIB card. If there's an interest, I'll look up the P/N's. Perhaps one handles comms synchronously by defualt, whereas the other gives the programmer enough lattitude to really get themselves in trouble.