Intermittent visa error BFFF0011 with viOpen

[monkeyfinger]

I am communicating with a Keithey 2700 DMM via TCP/IP and very occasionally, when I call viOpen, it fails with error code BFFF0011. Has anyone else experienced this before and if so, what was the cause? I have checked the ethernet patch lead and in any case (I think) it has happened on a second instrument on the system.

Does anyone have any suggestions as to what I might try?

Thanks

[Wilson54910]

Hi monkeyfinger 

Other than the BFFF0011 code you get is there any other message with it? Do you have a picture of the error?

When you say it happens " very occasionally" is there anything related between those occasions? (plugging in hardware etc) 

[monkeyfinger]

Thanks for the reply.

I am not sure how I would find out if there are any other error messages. I am not using LabView, I am calling VISA functions from a C++ application and the ViOpen call sometimes fails with the above error code. The network is never changed, nothing is plugged or unplugged at any time and everything is using static IP addresses. I don't think that there is a network problem because I don't get errors communicating with the Compact Fieldpoint devices on the same network although I do not use VISA to communicate with these.

To make matters worse, this equipment is active - in that it is recording important experimental data so I am restricted as to what I can do.

Does any of this help?

[JÞB]

The problem isn't VISA its that darned Keithley 2700

The poor device just hates re-opening sessions and sometimes goes out to lunch when repeatedly re-initialized.  The solution is of course to only open 1 session to the device and close it only when your application terminates.

[monkeyfinger]

Thanks for the suggestion. I think this would work. My only concern with keeping the instrument open is if it looses power - I seem to remember that it causes the calling thread to hang but maybe this is an easier problem to deal with!

I will have to give it a go.

Thanks again for the suggestion.

[JÞB · Accepted solution]

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@monkeyfinger wrote:

Thanks for the suggestion. I think this would work. My only concern with keeping the instrument open is if it looses power - I seem to remember that it causes the calling thread to hang but maybe this is an easier problem to deal with!

I will have to give it a go.

Thanks again for the suggestion.

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If the device looses power VISA (Modern versions of NI-VISA) calls will return with either a TMO error (Device found but not recognizing session handle) or an error 1 (Device not present, "still powered off")  Simple errors to handle by reconfiguring the device in the first case or prompting the tech to go see why the device fell offline in the second case. 

Any system that requires high reliablility needs a UPS!  So, power is not interupted.  Any Long term test needs a means to gracefully suspend for maintainence.

[monkeyfinger]

Just a quick update on this problem. I modified the code to keep the voltmeters open as you suggested and I have not had a single error over the last 3 or 4 weeks so I think it has solved the problem.

Thanks again fot your suggestion