Disable NI-VISA Runtime on XP

[srscott]

Sorry if this is posted to the wrong place. My question is about NI-VISA, but I don't see a forum dedicated to that.

My Tektronix oscilloscope interfaces to the PC via USB. The tektronix application is called OpenChoice. It uses NI-VISA to communicate with the scope over USB. NI-VISA is installed as part of SignalExpress_TektronixEdition_1.2.exe. The OpenChoice install requires only NI-VISA from the SignalExpress install. Since SignalExpress was enormous, and all I needed was NI-VISA, I downloaded NI-VISA Runtime 4.1 and installed that.

OpenChoice worked fine. However, now my older version of Matlab crashes on startup if NI-VISA is installed. I tried NI-VISA 4.2, but that didn't make any difference.

So I'd like to disable NI-VISA when I'm not running OpenChoice and don't need to communicate with the oscilloscope. Is this possible?

I'm running Windows XP, SP2.

thanks

-steve

[Ted_H]

Hi Steve,

There is no way to "disable" VISA besides uninstalling it.  I do have some questions though to clarify the problem.  How exactly does Matlab crash?  Are you running applications that maybe using VISA when Matlab crashes?   Are there any error codes or messages associated with the crash?  How do you know that it is VISA that is causing Matlab to crash?

If you can answer some of these questions, we'll be able to narrow down the cause of the crash.

Thanks,

Ted

[srscott]

Hi Ted:

Thanks for replying. My version of Matlab is an older version (R12). It crashes on startup when I try to launch. As the program is launching, I just see the standard Windows XP "encountered an error" dialog box asking me if I want to send info to Microsoft. The application never gets a chance to even open any of its windows. I never even get into  Matlab.

There is only one application installed on my PC which uses VISA, and that is the Tektronix OpenChoice application I mentioned in the original post. VISA was installed as part of that application's install process. Open Choice is not running when I try to launch Matlab. But apparently the VISA driver is running. I was hoping VISA was a service or something similar that could be disabled through the Services application.

Matlab worked fine until I installed VISA. In tracking down the problem, I did a system restore to the point before I installed VISA and Matlab again worked fine. Then I reinstalled VISA, and Matlab quit working. Then I uninstalled VISA, and Matlab started working again. Finally, I reinstalled VISA again, and Matlab quit working.

I don't have any way to tell Matlab to ignore the VISA driver. Apparently it just looks for it when Matlab launches, even if I don't have Matlab's instrument control toolbox installed. So I was hoping for a way to disable the VISA driver.

Thanks!

--steve

[JoshuaP]

The only thing that I could think of is to rename the visa32.dll before launching Matlab.  If they are trying to dynamically load visa32.dll and aren't handling it correctly it could crash.  However, if you rename visa32.dll it may think it is just uninstalled.

-Josh