DAQ device control reference bug

[Mister_Rose]

I have found a bug when using a reference to a DAQ (8.3.0f3) physical channel control. We have a control that is hidden from view in a tab container and we have found that until the control is painted on the screen, we cannot extract the "value" property. Attached is a VI to illustrate the problem. To replicate the problem, do the following.

1) Open the VI - you should see only the text control.
2) Run the VI a number of times - the text control will not update.
3) Scroll left and bring the DAQ control into view.
4) Scroll right and bring the text control into view.
5) Run the VI - everything works fine.

I can force the control onto the screen and make it briefly visible to get around it, but it looks sloppy.

[Wayne.C]

Brian,

Able to duplicate problem on my machine using LV 8.2 and DAQmx 8.5.   

[Sandra_T]

Hello Brian,

Thank you for posting to the discussion forum. I was able to test the issue with LabVIEW 8.2 and DAQmx 8.5. I agree that this is an issue. I will formally report this to R&D. Unfortunately at this time we do not have a workaround for this issue. I will post back here if I have any new updates on this issue.

Thank you for the feedback, it is much appreciated.

Regards,
  Sandra T.

Applications Engineer | National Instruments

[Jarrod_S.]

One better workaround would be to place the ring control on screen, but cover it up with a decoration the same color as the front panel. It would effectively be invisible to the user, but LabVIEW would still think it had to draw it, thus resolving the problem. I tested it and it works. It's at least better than briefly moving it onto the screen programmatically.

Just curious, though: is there a reason you can't just read the value from the terminal instead of a reference and property node and pass that value to wherever you need it?

Message Edited by Jarrod S. on 05-17-2007 10:03 PM

[Mister_Rose]

Just curious, though: is there a reason you can't just read the value from the terminal instead of a reference and property node and pass that value to wherever you need it?

We are using a cluster of references to the front panel controls to pass to various subVIs that perform the operations. Since we have many controls that are manipulated at various times, we decided it was easier to just pass them all around and dereference them where we needed them. This way we have one wire connecting the various VIs instead of a ratsnest of wire and logic.

The problem is that our main program front panel is a tabbed container. Our main window is in tab 1 and various other configuration controls are in the other tabs. We can't hide the control under something because the user may need to change it, so it would have to be accessable. The main front panel VI also does very little work and instead simply handles button presses and control updates and calls the appropriate subVI.