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TestStand User Interface in LabVIEW Hangs

Primary Software: TestStand
Primary Software Version: 4.1
Primary Software Fixed Version: 4.1.1
Secondary Software: LabVIEW Development Systems>>LabVIEW Base Package

Problem:
I am using a TestStand user interface built in LabVIEW and sometimes it hangs.  What are possible reasons for this hang?

Solution:
One possible reason for this hang is if you call a subroutine VI within an ActiveX callback VI.

In TestStand 4.1 and previous, there is a subroutine VI in the ActiveX callback VI for the Wait event that can cause this hang.  To fix the problem follow the steps below.

1. Open the Simple OI - Merge Errors.vi or the Full UI - Merge Errors.vi.
2. Open the VI properties window by selecting File»VI Properties.
3. Select the Execution category from the pull-down menu.
4. Change the Priority to Normal Priority.

The reason this hang can occur is when LabVIEW calls an ActiveX callback VI, the thread that handles the user interface waits for that callback to complete.  If the callback VI tries to call a non-reentrant subroutine VI, a deadlock can occur.

In LabVIEW 8.5.1 and previous, a deadlock can also be caused by interacting with front panel controls while an ActiveX callback was running.

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Report Date: 12/02/2008
Last Updated: 12/02/2008
Document ID: 4S18UPT3

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