Why does visa write hang with Labview 2009 instrument drivers.

[Steve_Block]

I'm having an issue with a code package that I'm running. The pacakge is very complex and was written by someone other than me. It runs fine while using the labview 8.5 drivers, however, when the 2009 instrument drivers are install there is a visa write call to an instrument where the software will hang up at the VISA write VI. I tried setting the timeout attribute but that makes no difference. I would expect that if the visa write did not work, that it would time out with an error instead of hanging up.

Some additional information. The instrument is an EPM which is on a GPIB bus with other instruments. When I place the EPM2000 on a serparate bus this problem goes away, but I want to be able to operate on the same GPIB bus.

Has anyone experienced a similar problem? What can I try to help troubleshoot the problem. I tried opening NI Spy but that shows no activity going on.

[JD_war_eagle]

Hi Steve,

This driver is a third party driver that is not officially certified or supported by National Instruments.  However, here is a resource for troubleshooting Instrument Drivers in Labview that may help you out: http://digital.ni.com/public.nsf/allkb/EFBD8C6A3ADC81EA862576AC00720DC8?OpenDocument

Also check to make sure that there have no been changes to the way this driver functions now.  As a third party driver, there may have been a significant overhaul in how this driver will be used.  Also the fact that it works on a separate GPIB bus may point to an addressing conflict of some sort.

[Steve_Block]

I'm sending raw visa write commands which are supported by NI.

[JD_war_eagle]

Hi Steve,

My apologies, when you said instrument drivers I assumed you were refering to the individual drivers for your instrument.  Were you refering to the VISA drivers?  If so, the latest version of these is 5.1.1 which can be downloaded here: http://joule.ni.com/nidu/cds/view/p/id/2659/lang/en.

Also are you able to communicate with this device using the test panels in Measurement & Automation Explorer?  There is also a tool called NI IO Trace (or it may still be called NI-SPY in 2009) that can be opened from MAX that monitors all GPIB commands sent and received on the machine.  Getting a log of the commands when the hang occurs may help to diagnose it.

It is possible this issue could be caused by opening and closing the VISA reference frequently in the code such as in a loop iteration.  Is this is case in your code?

[Steve_Block]

We use a specific version (The Labview 2009 driver set) as opposed to the latest because we need to control our configurations so loading the latest is not a viable option. I already tried NI-SPY and nothing happens. Communication with the instrument normally works, but this is a specific instance in a complicated peice of code where it is hanging up. Since it is hanging up inside of an NI vi, I'm wondering what else we might be able to try to troubleshoot the problem.

[JD_war_eagle]

Hi Steve,

Since the instrument communication works normally, the cause of this behavior must be something in the way your code is structured.  Some causes of this may be that VISA references are not being properly opened and then closed after you have finished using them or that VISA operations are being performed simultaneously on the same bus.  I would suggest to look through the code to see if there is any instance where these situations may occur.

Also could you give me some more information on your version upgrade?  You said you installed the 2009 driver set, but what version are you using for development of this program?