Instrument Control (GPIB, Serial, VISA, IVI)

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VISA Close makes LV freeze

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Hi,

 

I'm using VISA Read & Write to interface a FTDI FT232BL USB-to-Serial converter. The FTDI driver created a virtual COM port.

 

Everything worked great with LabVIEW 8.0 and 8.2, and some weeks with 8.51. But suddenly my VI froze when I ran my shutdown code.

Fortunately, I was able to track it down to VISA Close, with just displays that it's running (using the yellow bulb symbol) but never finishes. I can close other LV windows except the Project Explorer and the running top-level VI. The red Abort-button is clickable but shows no effect.

The Open VISA Session Monitor VI in the labview\vi.lib\Utility\visa.llb shows no open VISA sessions.

 

When I kill LabVIEW using the Windows task manager, another LabVIEW.exe process stays there (it says I don't have the right to stop it) and a new LabVIEW session freezes at once.

 

I've activated "auto close VISA sessions" but it doesn't seem to make a difference 😞 

 

 

Has someone experienced similar difficulites? 

 

 

I tried VISA 4.3 and 4.4 with LabVIEW 8.51 on Win2000. It also happens as a built .exe on a different PC, and also at a different GUI with uses the same hardware interface VIs (the ones with used VISA open/r/w/close)...

 

regards

Marco 

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here's a picture:

 

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sorry for spamming, but it seems I'm too slow for the edit time slot.

 

 

The VISA flush has no effect on the freezing. 

 

And I have to correct myself:

after I kill LabVIEW using the task manager, the original LabVIEW.exe process stays there and still uses about 80 MB RAM, and is not kill-able (even not with admin priveledges), but all LabVIEW windows disappear.

 

regards

Marco 

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Solution
Accepted by topic author marco.geisler

This points to a hang in the release of the FTDI dll.

What version are you using? Did you check for an update on the FTDI web?

greetings from the Netherlands
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Thanks for your answer.

 

I've downloaded the latest driver some weeks ago, but the update seems to have failed.

Now I'm using V2.04.06 (the latest version) and we'll see if it crashes again...

 

The bug ID 93267 mentioned here should be a problem as I'm using VISA 4.4.1.

 

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Seems to be solved 😄

 

On 2 PCs, installing the latest FTDI driver seems to be the solution.

 

On the PC running the executable, problems disappeared when i re-installed VISA 4.4.1 on the PC building the executables/installers.

 

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