VISA problems with upgrade from LV 2010 to 2012

[joe5213]

Hello, I recently upgraded from LV 2010 to LV 2012 and am having troubles with my VISA Write calls. In 2010 my VISA Writes had no problems. I've attached a screen shot that shows the error message when in 2012. 

I always get this error message and am having trouble finding a solution. I am sending GPIB commands to an HP8510 Network Analyzer. I was sending multiple commands per VISA Write but have decided to break out the commands so I have one command per VISA Write. That seems to have helped but I still keep getting this error message. I have made sure that I always do a VISA Close after my VISA Write/Reads. Could this be related to the version of VISA I have installed?

Here is my configuration:

I have tried using a VISA Clear before my VISA Writes but that doesn't help. If anyone has any ideas or some rules of thumb for using VISA Writes/Reads please let me know. 

Thanks,

joe

[Dennis_Knutson]

You have not mentioned what version of VISA and GPIB you are using or shown how the devices are listed in MAX. The message indicates the resource name does not exist so do a rescan and check the alias.

[mikeporter]

Also it appears that you are constantly opening and closing the resource. This extra work typically isn't necessary.

Can we see what you LV code looks like?

Mike...

[joe5213]

Hello and thanks for responding to my post. I followed your recommendations of not opening and closing every VISA connection. I removed all VISA opens and all VISA close and also for every VISA Write I also connected an ERROR IN, which before I did not connect on for any of the VISA Opens. Once I made those changes things started working just fine. Thank you very, very much. joe

[JÞB]

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@joe5213 wrote:

Hello and thanks for responding to my post. I followed your recommendations of not opening and closing every VISA connection. I removed all VISA opens and all VISA close and also for every VISA Write I also connected an ERROR IN, which before I did not connect on for any of the VISA Opens. Once I made those changes things started working just fine. Thank you very, very much. joe

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That would explain it.

In LabVIEW 2010 ONLY there was a bug where VISA Reads and Writes would allways return synchronously and the asynch flag was not respected.  Converting to 2012 removed this bug and your reads began to operate asynchronously.  While an asynchronous read is in progress, an error occurs if you execute another write or asynchronous read operation.  Enforcing dataflow by wiring the error chain would resolve the issue you saw (and is good practice anyway):smileywink: