Get image invoke method gives blank image when I try to capture waveform graph picture

[Ben]

I belive LV 8.5 had some issues with updating the image of graphs that were on non-viewed tab pages but I can not speak for trying to grab the image.

THe work-around I normally suggest trying are all techniques that force a redraw of the screen and or object in question. All of the following may not be required but may help.

Before the data update of the graph fist defer front panel updates then hide the graph. Update the graph, un-hid the graph, then un-defer the FP updates.

In you case is sounds like the image data may be empty. If so you can use that as a trigger to invoke the "Jiggle the handle" appraoch I outlined above.

Yes I realize the above will take some learning of LV to implement.

Sorry but I do not have an easy suggestions.

Ben

[mavi]

Hi

I have tried different delay times, flat sequence and both also. Some times it gives correct pictures but some times blank .If any body knows how Get image  method works or alternate code to capture wavegraph image except export image node that is also behaving in same way as Get image, Please reply?

[mavi]

Hi Ben,

could you please explain me  in a little bit detail.

[mavi]

Hi

I modified the vi as Ben suggested but still getting same results - some times correct some times blank images.

[Bublina]

If you are having trouble with the current solution, you can do it some other way around.

Try getting the image via export image invoke node.

[mavi]

I don't find Forceredraw node in labview 8.5.1. Appreciate your active participation.

[Bublina]

You do not need forcedraw, the export image is enough. I thought it is in there, I tried to save these two nodes for 8.5 version and it did not fire any errors.

[mavi]

Belive on me Export image method is doing same as Get image means it also give blank images some times not every time.

[P@Anand]

Are you able to see the plots all the time in the graph?.

[Ben]

I ran your code under LV 8.6 with no errors.

Bumped up the code to spit out 120 images still OK.

So I suspect we are dealing with two possibilities to explain what you are seeing.

1) Bug in LV 8.5.1 that was fixed in LV 8.6

2) Something with the machine you are using. Occationally the Graphic acceleator setting for the PC display are set too high that cause problems. These are usually manifest as weird graphics but I can't say I have seen or read about every problem.

But I am leaning toward it being a bug in LV 8.5.1

Ben