Question about using LabVIEW DLL from CVI...

[Joe Roberts]

Windows 2000 SP1
TestStand 2.01f
LabWindows CVI 6.0
LabVIEW 6.1 Runtime

We have a framework based on TestStand and CVI. A customer has supplied us
with a DLL written in LabVIEW 6.1 that we need to call from a CVI test
library DLL. They supplied the DLL and a .H file, exporting a single
application function. We generate a .LIB from the .H file using CVI. We
installed the LabVIEW 6.1 run-time. We add the .LIB to the CVI DLL project.
Everything compiles and links fine. Stuff runs okay except...

However, periodically, we experience an application 'lock up'. If I bring
up task manager, on the 'Applicaions' tab, the item name LabVIEW is marked
as 'not responding'. Sometime it seems to come back after a long (5+
minute) del
ay, sometimes not at all. The LabVIEW item is the only item
marked 'not responding' and the LabVIEW item shows up only when we link the
LabVIEW DLL into our CVI test library.

Is this a valid set up? Is it valid to call a LabVIEW DLL from CVI which is
in turn called from TestStand?

Is there any addition steps we must take to use LabVIEW DLL in a
TestStand/CVI environment? Right now we just call the LabVIEW DLL function
from C as if it were in a 'normal' WIN32 DLL. Is this valid?

Does anyone have any suggestions on what to check or what might be causing
these hang-ups?

Thanks,

---
Joe

[Jeremy Braden]

Wow, that sounds like a complicated program. Have you tried to remove some of the layers? Does the program hang if you call the LV Dll from straight CVI? Also have you used something like a debug print statements in CVI to verify that the code is in the LV dll when it hangs (I know what the task manager says)? It sounds like it might be a deadlock situation. Does the LV dll call any global resources?

You might also consider posting to the test stand forum.