VISA Read hangs. Get Resetting VI dialog on abort.

[Craigginsberg]

Hey,

I receved your message to late i had ended task and restarted. I will try IO trace in MAX next time it comes up and report my findings here.

I happen to have a very power full magnet at my disposal, i will try and generate EMI using that and see if it generates the problem quicker.

~Craig

[David22JRA]

Hi Craig

Have you tried to use a LabVIEW example (LabVIEW>>Help>>Find Examples>>Search Tab>>Serial)

Regards

[Craigginsberg]

Hey David,

Looking at the examples there is no diffrence in the implementation of the VISA read and write.  If it gets stuck inside a VISA read and never times out then the program will hang at the VISA read block no matter what the implementation is. This problem has plagued me for years.

~Craig

[LindsW]

Hi all,

For those of you communicating with GPIB instruments, I would highly recommend upgrading to NI-488.2 15.0. There are a number of bug fixes included in this driver that resolve hangs during communication.

If after upgrading to 15.0, you are still experiencing this issue, we’d definitely like to investigate it further. As Alisha_P mentioned previously, if you are able to reproduce the issue we’d like to get two IO traces from you:

• 1 with LabVIEW disabled
• 1 with LabVIEW and VISA disabled

You can change these settings in Tools>>Options>>View Selection.

For both of these traces, make sure you include the calls before and during the hang. In addition, please follow the steps here for configuring IO Trace prior to starting a capture. Lastly, under Tools>>Options>>General>>Call history depth, make sure you make this number large enough to capture your entire test.

[Craigginsberg]

hey get this error when trying to open Visa test panel

Error opening resource:
ASRL27::INSTR

VISA:  (Hex 0xBFFF0072) The resource is valid, but VISA cannot currently access it.

I will try and install the 2015 visa next and post the log term result here

[Dennis_Knutson]

That error is common and if you had done a search for it, you would have found the solution. It is not related to the problem in this thread and updating VISA will not help. Just close the other application that is using the serial port.

[Craigginsberg]

I do not have any thing else open that i know of.

Would you refering to the VI it self thats stuck in the Visa read?

[LindsW]

Hi Craigginsberg,

As Dennis mentioned, it sounds like you are having a different issue. In your case, VISA Open is returning an error. This thread is focused on calls to VISA Read that are hanging inside the function call and not returning an error. Take a look at this article, and if you continue having problems please start a new thread.

[Craigginsberg]

Hello,

No i am definatley in the Right place. The Visa read in my VI hangs DOES NOT RETURN ERROR AND DOES NOT TIME OUT. Resetting vi on abort happens with an end task or process end, the results vary often there is a system wide crash when i try and end task.

The error above is what i experience when trying to open a "visa test panel" in MAX while this error condition had occurred. I was instructed to do this by some one in this thread in an attempt to perform an “I/O trace”

THE ERROR DID NOT COME FROM THE VI BECAUSE THE VISA READ IT IS STUCK IN WILL NOT TIME OUR OR RETURN AN ERROR OF ANY KIND. Hence it will Not be possible for the VI to return an error. The error is not from my vi it is from MAX

And by error condition i am referring to "Visa read in my VI hangs DOES NOT RETURN ERROR AND DOES NOT TIME OUT"

So at the same time while this error state is occurring. I tried to "open a VI test panel" in MAX and i received the error posted above.

I updated to VISA 2015 and installed the GPIB drivers recommended above. I believe i am experiencing same a problem even more frequently now. I will continue to investigate. I have spent a year developing my app, i will not be going any were.

[Albert.Geven]

Does your vi use 'end character enabled'?