Time stamp control dialog kills System Exec.vi !

[Blokk]

Hello!

I just experiance a really strange behaviour in my application. I managed to reduce it to a much smaller VI, please do not look at the framework but at the actual problem, this test MAIN vi looks like this since it is a skeleton of a bigger application (i had to remove many non-relevant and confidential parts).

So. I have a USB watchdog relay from a 3rd party company, which I can use perfectly in my application via a supplied EXE. I call this exe from LabVIEW using the System Exec.vi , and it works perfectly and the Watchdog functions as it should. However I see a strange bug (?): if I launch a Time stamp control dialog browser window, it "pauses" somehow the System Exec.vi. So my watchdog command setting stops, relay opens, problem!

I zipped my test application and I can reproduce this same problem even if I just call a command line PAUSE win command. Note that, in my real application, the Time stamp control is located in a separate, dynamically callled (call and forget method) VI, but I get the same bug!!!

Steps to reproduce the bug:

1. start my application
2. observe as the bottom loop iterates
3. Click on the Time Stamp control's browser to pop-up the dialog window.
4. You can see the iteration of the bottom loop stopped (DAQ loop iterations)
5. if you close the dialog window, the bottom loop continues execution

What the heck is this??? 🙂

How is this possible, why there is "interference" between a totally separated control and a bottom loop System Exec.vi ???

Thanks for any suggestion!

In my real app, as a workaround, I just hide the browser element of the Time stamp control...

[tst · Accepted solution]

LabVIEW has a software component called the root loop which is used by different parts of LV. Opening that dialog blocks the root loop, which is most likely what blocks the DLL call inside the system exec VI. You will probably be able to also do this by opening a menu and leaving it open.

You can do a search for the term to find more about this, but I don't think there's anything you can actually do about it.

[Blokk]

Thanks! Yep, I can do a workaround, like create my own time stamp dialog window to pop-up if i wanna be "fancy".

But this is important to keep in mind, if we use the SystemExec vi!

If someone can explane this issue/feature deeper, I will be happy, but I mark this above post as solution, thanks! 🙂