What should I do when I can communicate with my instrument through NI MAX and other programs, but not LabVIEW?

[optoelectro]

Hi all, this is an issue I've had a few times before in one form or another.

I use a Boxcar Integrator (SRS 245 is the interface) for my experiment. I connect to it via GPIB using my Agilent GPIB/USB interface. My program runs in LabVIEW, and I have successfully used it in the (very recent) past.

However, sometimes, if I exit LabVIEW or something, weird stuff starts happening when trying to connect to it. For example, after exiting LV and starting it up again, and then attempting to run my program, it throws the error:

Error -1073807339 occurred at VISA Read in OR_Boxcar_ReadAnalogPort3.vi->OR_Boxcar_SimpleTest.vi

Possible reason(s):

VISA: (Hex 0xBFFF0015) Timeout expired before operation completed.

Which basically means it can't connect for some reason or another (don't worry, I'm using the right GPIB address).

So then I go to either NI MAX or Agilent's equivalent (Keysight Connection Expert), go to the VISA communication part for either, and manually communicate with the machine. And it works! So clearly my computer is communicating with the machine at this point, but LabVIEW won't.

What could be causing this, and what could I try? thank you!

[Rscd27]

Can you attach a simplified version of your VI?

[optoelectro · Accepted solution]

Oh damn, I forgot about this! I solved the problem, it was actually a 'me' problem, not a LV problem. Even my solution wouldn't help anyone else who finds this. I was trying to read from my instrument but it is in synchronous mode, so it throws an error if you try to read from it when a data point hasn't been loaded into its buffer. I was doing something unusual so there wasn't a data point being loaded into its buffer.