queue handle interference with visa communication

[GerdW]

From time to time I get an error message from Labview with Error #1 on an Release Queue subvi (invalid parameter). How can this be?
Hint: I have a straight connection from Obtain Queue to Release Queue, I dont use globals for the handle.
Can the handle be destroyed somehow?

Best regards,
GerdW

[Ben]

I will assume you are using LV 6.1 or later. (Note Queue references changed between LV 6.0 and 6.1 in that each obtain queue returns a unique reference now. Previously the same reference was returned.)

The Release Queue will destroy the queue and invalidate all reference to the queue if the "force destroy" boolean is true.

I suspect that elsewhere in your application, there is a realease queue being called that has this input wired true. I also have to guess that the destroy is occationally executing between when you obtain the queue reference and when you release it.

The attached VI (in LV 7.0) and jpg illustrate this condition and return the error code 1 as you mentioned.

Run the VI in exection highlihting and you will see how this hap
pens.

BTW
If you are seeing this in RT, I have another story that applies in that environment.

I hope this helps,

Ben