Getting an error when closing a VISA session

[lmtis]

I have a VI that uses VISA to talk to an instrument through aLAN/GPIB gateway.  It works fine when talking to my laser.  When I try to communicate with my OSA, all of the commands work, and I get the data, but I get an error message from the VISA Close.  The OSA is an older unit, but I thought that the VISA stuff was all internal to the PC and OS.  Any help or insight would be appreciated.

Jim

[smercurio_fc]

It would help if you provided the error code that you're getting.

As for VISA, it's basically just a software layer between your application (in this case LabVIEW) and the specific driver for the bus that you're using (GPIB, Serial, TCP/IP, etc.). It doesn't really have anything to do with the OS.

[mfitzsimons]

Sounds to me that you are getting the error before you VISA Close.  Ar you displaying the error in more than one place in your code?

Matt

[lmtis]

Sorry for the missing info.

Error code:  –1073807338  

Which in NI help is indicated as:  VI_ERROR_CLOSING_FAILED  -   The VISA driver failed to properly close the session or object reference. This might be due to an error freeing internal or OS resources, a failed network connection, or a lower level driver or OS error.

Watching the VI execute in highlighted mode, there are no errors out of any of the VISA writes or reads before the Close.

Jim

[lmtis]

BTW - running LabVIEW 7.1 on XP Pro.

Message Edited by lmtis on 03-02-2006 07:52 AM

[Chris_R. · Accepted solution]

Hello,
What version of NI-VISA do you have?  There was a problem with the viClose on earlier versions of NI-VISA (before 3.1).  I suggest upgrading to the latest version here.  If you don't already have the latest version, try it and see if it fixes the problem.

Chris R.
Applications Engineer
National Instruments

[lmtis]

Chris,

How do I find out what version of VISA I have installed? 

Jim

[Chris_R.]

Hello,
You can go into Measurement and Automation Explorer from the start menu and expand the "Software" folder from the configuration tree.  Find NI-VISA and click on it.  The version number should then be displayed in the box on the right side.  Let me know if you have any trouble.

Chris R.

[lmtis]

Thank you Chris.  Upgrading VISA from 3.1 to 3.5 not only fixed the Close VISA problem, but also fixed NI Max.  It was rebooting my PC every time I ran it, but now it works fine.  Thanks for the advice.

Jim

[Chris_R.]

No problem!  I was happy to help!  Best of luck to you!

Chris R.
Applications Engineer
National Instruments