reentrant execution of controls

[tst]

We can't help you with where to begin either, since we don't see your code and your explanations don't mean anything to us.

I can make guesses, but I have no idea about their relation to the truth:

1. You say you use ActiveX to connect to a (presumably) remote device. Is the ActiveX code thread-safe? Is it possible that is what's blocking you?
2. The second part is probably a bug in your code. Presumably whichever mechanism you use to clear the info does the wrong thing. If you want to debug it, add some probes or indicators to that area of the code and see what happens.
3. If you're concerned that the problem is with running all the parallel VIs in the same process, you could run them as separate processes if you compile it into an executable and then call that 16 times. You will have to add the line AllowMultipleInstances=TRUE to the app's INI file. Personally, I wouldn't prefer this option, mainly because it makes the communication harder and has its own potential problems.

[mrbean]

What steps can I take to see if the ActiveX code is thread-safe?  Also, I originally wanted to go the route of calling multiple EXEs but I wasn't sure how to do that.  I don't have an "AllowMultipleInstances" in my ini.  Do I have to add it, or should it already be there?

[tst]

I have no idea how to check for thread safety in an ActiveX class. I assume it should appear in the documentation, but if not, there may be other ways. I would probably just test it by trying to run the code in parallel, but I'm not sure that's guaranteed to give you a definite answer.

As for the line, it's not in the file by default.