get image invoke method: no image if Front Panel minimized 8.2.1

[joe s]

Hello all,

In my application, I have to run a Labview executable eith the Front Panel minimized, and it is not possible to run it unminimized or to use a Front panel property node to momentarily set the Front panel state to standard and then back to minimized during the get image invoke node

 get image invoke node does not return an image when the front panel is minimized

what can we do to resolve this problem ?

I have an example VI that I have atached.

Steps to reproduce:

1. click run

2. specify the name of a jpeg output file within 15 seconds

3.  wait for first few snapshots to occurto occur

4. minimize

5. wait for next snapshot to occur

expected result:

 you get correct spanshots of the table after steps 3 and 5

actual result:

 no snapshot after step 4

any help would be greatly appreciated

thanks in advance

JS

[smercurio_fc]

This is by design, and it is documented. From the Help on the Get Image method:

If a front panel is not visible, LabVIEW does not update the values in the objects on the front panel. If you call a VI whose front panel is not visible and you use the Get Image method to create an image of a front panel object, the image does not reflect any value changes that occurred when you ran the VI.

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joe s wrote:
 

what can we do to resolve this problem ?

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Don't minimize the front panel.

Other comments:

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1. click run

2. specify the name of a jpeg output file within 15 seconds

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Or... a better solution is to feed the path into a shift register. If the path is initially empty then the Write JPEG VI will ask for a file, and the path output of that VI will be the new path that you can feed to the shift register on the right.

Also, on the left you are writing a value to the indicator and also using a property node. This is redundant.

[chilly_charly]

Sorry smercurio, but the Help says also : "If you want the image to reflect value changes, make sure the front panel is open before any values change. If you do not want to display the front panel but want the image to reflect value changes, create a Property Node from any front panel terminal on the block diagram of the VI for which you want to create a front panel control image."

Actually this seems to be a bug, specific to the Widows platform, since, on my Mac, Get image behave as described in the Help, and the image is correctly saved. The same vi, running on a PC, returns only a small chunk of the table control.

[smercurio_fc]

I stand corrected. You're right, this appears to be a bug. It still exists in 2009 as far as I can tell.

[Roy_F]

A similar problem was reported via CAR 35573. I've updated that CAR with your information. If it turns out the two issues are not related, a separate CAR will be created.