Teststand duplicate visa session

[MacDroid]

I have a teststand sequence that uses several GPIB instruments.

Using the 'Open VISA Session Monitor.vi' I can see that, when it hits the initialize for the first instrument, a session for each instrument is started.

Except one instrument starts 2 sessions.

This runs fine the first time the sequence is run after a reboot of the PC and 'Open VISA Session Monitor.vi' shows all sessions have ended. But, the second time, again sessions are created for all instruments with two for that particular instrument.

Later in the second run, several calls to the instrument with 2 sessions work, but a later call  fails, complaining that a required input to the vi can't be empty. (Remember this call worked fine first run.)

Is Teststand supposed to create sessions for all GPIB instruments automatically on first access of any VISA device?

Why is it creating 2 sessions for just one device?

Regards,

Mac

[Dennis_Knutson]

What sort of steps are you using? The IVI steps shouldn't be creating multiple sessions. If you are using LabVIEW steps with a driver, then it's possible the VISA Open in an Initialize VI is set to open a new session each time it is called. Please provide the details on what exactly you are doing.

[MacDroid]

I don't know a lot of details.

I am using Labview drivers.

One thing I discovered was that the first time any Labview driver is called, a session is created for all 11 devices in the sequence.

The first driver call is NOT the device with the error.

Two sessions are created for the device with the error. For a total of 12 sessions.

[Dennis_Knutson]

It does sound like one of the Open functions is set to create a new session each time. Look at the block diagram of the initialize function. The open is not even required so you can delete all instances.