How to stop LabVIEW indicator from flickering?

[nitulandia]

Hello all,

The version in use: LabVIEW 2011

You'll need two machines to see the issue I'm about to present. One of them will obviously have the LV development suite installed on it, while the second one will only have the Run-Time Engine (RTE) installed.

Step One:

Open the attached project, run the VI, and you'll see that the "simple timer" works as expected (the display does not flicker)

Step Two:

Create an executable and copy it to the machine that has only the RTE installed. Run the executable and you'll see the issue then: the display flickers! I'm trying to figure out a way to stop that behavior.

Would you please share your thoughts?

In advance, thank you very much.

edp

TimerProject.zip

[nitulandia]

Hello,

In case you were following this one... here is an update:

I have found a work around! But regardless, the "flickering" problem I'm seeing on my production machine MIGHT (not proven just yet) be related to HARDWARE!! yes, the video drivers on each of my machines is different!! My dev machine is a GATEWAY - and no, I'm not getting a commission for using the brand-name :-) where as my Production machine is an "ACER". One of my colleagues has an "ACER" as his dev machine, and the "flickering" problem is there as well!

In any case, take a look at the workaround. First png on top is the original VI with the flickering problem, and the 2nd png on the bottom is the workaround

[viSci]

I had a problem with a flickering numeric display and was able to fix it by placing caption text inside of the indicator. In my case it was a time display so the caption 's' to the right of the left justified numeric seemed fitting.

[Beuf]

Still valid in LV2020 on brand new HP workstation, tip of viSci works for me. Just placed a caption '.' over the control where it isn't visible and flickering is gone!

[Rolf Kalbermatter]

1 hour ago, Beuf said:

Still valid in LV2020 on brand new HP workstation, tip of viSci works for me. Just placed a caption '.' over the control where it isn't visible and flickering is gone!

That's because if you do any overlay of anything in LabVIEW, LabVIEW will be forced to fully redraw the entire control every single time rather than trying to use optimized region update APIs in Windows. And the graphics driver for your video card seems to have some trouble with proper region drawing.

Of course full redraw will be usually considerably slower so it isn't a perfect solution at all.

Edited October 16, 2020 by Rolf Kalbermatter

[Neil Pate]

I normally place a small transparent decoration over the control and this fixes it. Especially useful for tables where you are updating a reasonable amount of text.

[Lipko]

Same trick can solve flickering of the cursors of a graph when the graph data is updated. However, it can result in seemingy unrelated errors, for example triggering an autoscale on an axis with property-node doesn't work the same way as without the transplarent overlay, so far as I remember. This is obviously just a simptom of some updating (order) thing. So if you have any "special" behaviour of your control/idicator, you better test everything (which is close to impossible), or try to recall this hack if something that once worked stops working as expected.