Visa session lack of response

[UnfortunatePOSMuser]

After one attempts to open a visa session with a serial or GPIB device that is ethernet connected and the instrument is not found (for most any reason, cable not connected, instrument switched off, wrong GPIB address ...) when the problem is corrected, LabVIEW refuses to open a VISA session with it even though the instrument is now present and working. This problem also happens once a VISA session is established and for one reason or another, the instrument is off line when the VI tries to contact it. One must quit LabVIEW entirely and start it once again before LabVIEW will open a session with that device. It seems as though LabVIEW makes only one attempt at contact and then writes that device off until such time that LabVIEW is re-started.
Does anyone know of a solution to this problem short of quitting LabVIEW and restarting it to bring things back in order once again? A work-around possibly?

[JoshuaP]

What version of LabVIEW are you using? I have LV 7.1 and I don't see this problem. I tried placing a VISA Open and VISA Close in an application. I can turn my instrument off and it reports errors. Then, I can power it back up and run the application again and it works fine. Also, what is the exact error code that the VISA Open is returning?

I would suggest making sure you have a VISA Close at the end of your application, even when an error occurs. Just to make sure it clears everything out.

I hope this helps out.

-Josh

[UnfortunatePOSMuser]

Thanks Josh,

Yes I do also have LabView 7.1 running on a MAC OSX and a PC Win2Kpro. I also have been using a visa close religiously. I did discover the cure, on the MAC at least was to create a static configuration for the instrument with VisaConfig. That took care of the problem. I had been using a dynamic configuration (type the whole thing in the Visa Resource Name box e.g. TCPIP::125.55.236.95::GPIB0,7::INSTR ) The problem I described was the only down side. I had exactly the opposite problem with LabVIEW 6.1 and win2kpro when I did use a static configuration and an alias in MAX. Go figure, each version of LabVIEW and each OS combination has its' own bugs. I do so wish they could rattle them all out.

Thanks for your suggestions and ans
wer.