Labview Auto Close VI Reference?

Question

I'm having trouble with what I think is Labview auto closing a VI reference. Here's my setup:
I have a number of VI's that require a termination when the program ends.
Upon the first call of the VI, it essentially registers a termination VI that will call that VI with the terminate flag set. This is done by opening a reference to the termination VI and adding it to an array in an FGV.
Upon exit, the VI containing the FGV is called. It runs each VI in the array to terminate any VI's that need it.
The problem is, it keeps complaining that the VI reference is not valid. I've check at the point of putting the VI in the array to be sure the VI reference is valid an it is fine. It's only when it tries to call it upon exit that is has a problem. Would labview close any references to VI's automatically?
I've used this scheme successfully before, but on an older version of Labview (8.0). Has something changed since then?
Solved!
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Answer 1

Once the VI hierarchy that called the Open Reference goes idle, any reference is automatically closed. LabVIEW does not have a reference count system like Java or Lua, where the runtime environment controls the life time of objects depending on if they are assigned to a variable. Instead it controls the life time of it's "objects" (almost anything that is represented with refnums) by the lifetime of the top level VI in whose hierarchy the Open call was done.
So if you have a startup VI that spawns your main VI and also creates the refnums and then terminates, those refnums are gone the instant your startup VI stops executing.You will have to make sure the refnums are opened inside a VI that stays executing for the entire lifetime of your application, which in most cases would be the main VI that starts eventually other sub panels as needed.
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions