USB 6009 lock-ups?

Question

Hello,
I'm having a strange problem with my newly aquired USB 6009. I've written an app to read the temperature from a temperature controller using the 6009 and that all works fine. However, the problem comes when I port this code into another application. The code is intended to run in a parallel loop to the main execution loop, to continuously read the temperature whilst other data is captured and process (all done in the main loop). Both applications run quite happily when separate. When I bring them together the applications sometimes, but not all the time, refuse to quit and just lock up. I have no idea what is happening as it is not a case of one loop remaining running (I've tried separate stop buttons) and they will run together quite happily. The problem only comes when I hit the button that terminates the main loop (this also triggers the other loop to stop - I'm sure this bit works as I've used the same method in another vi).
The main loop should, in theory, just close. The loop with the USB reads (using DAQmx Base) will stop and then clear the task (DAQmx Base Clear I think). Sometimes the DAQmx Base Clear runs and the program stops fine, other times it runs and the program locks, other times it locks as soon as I hit the quit button.
Any thoughts as I'm completely stumped on this one? Like I say, apart from the one button triggering both loops to terminate there is no link between the two loops.
My only thought is it could be a USB issue as the PC also has a USB keyboard and mouse. I know from my home experience, when for instance plugging in my camera, it can cause the USB to lock if, say, my USB modem is running.

Answer 1

See the thread
http://forums.ni.com/ni/board/message?board.id=250&message.id=13722
John Weeks
WaveMetrics, Inc.
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www.wavemetrics.com