Screen Lock up

[Nariman]

Hi,

I am developing a big application Using LabVIEW 7.1, and the project is almost done and is currently being V&Ved. We ran in to a problem however that seems rather odd and I thing might be a bug in LabVIEW. I was wondering if anyone has ran into this problem before or knows who to resolve this. Here is the situation:

When I change the value of a numeric field and immediately without pressing enter or clicking the mouse change the tab (I have big tab view in my program with lots of controls in each tab), the screen freezes and does not respond to mouse or keyboard. I checked and the background process and the code is still running but it seems that the LabVIEW's "View/Control" module which should be in charge of updating the screen, and getting inputs from the screen, lock up. I am guessing that part of it might be due to the speed of the computer that I am using (P2 550, 512 MB ram) and if I use a faster computer the problem might go away. I haven't had the time to run the application on faster computer yet. BTW the problem is there on both LabVIEW debug mode and the executable made with application builder.


helps, suggestions, and comments are greatly appreciated.

[drval]

Check out the Front Side Bus speed of the system -- that can be a factor as well -- but I suspect that one issue may very well be the overall spec and setup of your computer.

[drval]

Check out the Front Side Bus speed of the system -- that can be a factor as well -- but I suspect that one issue may very well be the overall spec and setup of your computer.

[tst]

One thing would be to make sure you don't have an event structure locking up your screen.
If you have a value change event for the control AND it's set to lock the FP until the event completes AND there is some code in there that's still running, that's probably it.
You can easily tell if it's this, because if it is, you will have no problems in the block diagram.

[Nariman]

thanks for your inputs guys.

tst I think your idea might be a possible reason as well. Actually I thought of that myself but I don't know a way to test this idea. I do have a value change event for the control however I don't lock the front panel during the event. I do call a subVI though but that subVI just adds units to the new value and saves it in a Global variable. If you know of a way to test and fix problem I will appreciate your input.

[Megan B.]

Hi Nariman,

Are you able to replicate this problem in a smaller application? A much smaller application that just has a tab control and an event handler for the value change would be a great place to start. If that runs without error, than you can build up from there to see when the trouble starts.

Otherwise, it could simply be a system specs issue as suggested.

Hope this is helpful!

Megan B.
Applications Engineering
National Instruments

[tst]

Just to be sure I understand correctly, the screen locks up when you change the value on the numeric and then try to change the page on the tab, or does the tab have nothing to do with it?
In any case, does this happen only after changing the numeric? Does it happen if you change the numeric and do something else before changing the page? Does it happen when switching to every page? If not, what is on that specific page? As was said, an example would be very helpful (the smaller, the better).

Like I said, if this is caused by an event locking the screen, you should still have free access to your BD (place probes, open subVIs, open other VIs). Just open it before you run the VI. You can try canceling all the locks in the event structure to make sure it's not caused by this. Also, once it stops, you can try turning highlight execution on to see where it is.

Of course, testing it on a faster computer wouldn't hurt and should also be tried.

[Nariman]

Thanks for the input Megan. I have tried it on a smaller application using a simple tab and events before and I don't get this problem over there. I suspect it is because this application is huge compared to the test application that I build.

tst Here is the situation: when I change a field in criteria cluster (I don't press enter or click anywhere on the screen after the new value is typed in) I just click on another tab (for example Extract tab), the page switches to the extract tab but then it locks up. This doesn't happen all the time though and it happens randomly. What I am suspecting is that the mouse click will invoke two events:
1. The value change event for the Criteria occurs.
2. The event to change the tab page occurs.

My hypothesis is that these two events sometimes interfere and therefore the view/control module of labview locks up. Also as I said before I have checked that the block diagram and it is running the code and it is working fine but it seems the screens doesn't respond to mouse event. I am guessing this since the mouse Icon does not change as I move it over numeric fields.

I have also attached three pictures.

1. The code where the value change event occurs (please note that the Mutex used there, is not occupied when the event occurs and there is no wait for the mutex to be released)

2. The criteria tab page where I change a criteria.

3. A locked up screen after the tab page has been switched. (Note that the mouse icon is locked, when it is in the window but when I move it over the minimize icon on the top right corner the mouse icon changes and I can minimize and maximize the screen)

I hope this helps you guys understand the situation better and thanks for all your inputs. I will soon try this program on a faster machine and let you know about the results.

[Nariman]

Criteria page

[Nariman]

Locked Screen