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xy graph on TAB container does not update

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I have attached a simple VI, and I would like to understand why I see this behaviour:


When I run the VI when the first tab page is visible (where the xygraph is located), I get what I expect: I calculate the offsets, and I redraw the graph with property node.

But If I run the VI when the second TAB page is visible, I get a wrong result, the graph does not make the offset calculation and modification on the graph. (Array gives zero elements)


Does it mean that, if my graph is in a TAB page what is not shown, I cannot use its property nodes ? 

Thanks for help!

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Message 1 of 4
Accepted by topic author Blokk
08-27-2015 04:09 PM

Are yous eeing this for any property node or specifically the cursors?  You can see the same behavior if you make the XY Grpah invisible but leave it on Tab 1.  It appears that the cursors properties don't work properly if the XY Graph is not visible.  I would consider this a bug.


How do you determine the cursor values?  Is a user setting them, or are you calculating them and setting?  If there are hardset or calculated at some point, store the cursor values and use those instead of looking at the cursor property.


If the user selects them, use the event structure to trigger an event when the user releases the cursor.  Get the cursor values at that point, store them, and use those values.

Message 2 of 4



Actually I do know already several working solutions, to avoid this problem. You mentioned some of these.

But here I am purely interested about this behaviour. Is this a bug, or this is a normal behaviour? Like LabView saves system resources, so If we do not see a graph on the front panel, it does not update its values? (i mean the cursor values).

So I would like to see and understand whats going on when someone runs this particular example. (so I do not use this in a real project, this is only to show and examine this behaviour).


Also a bit dirty workaround: I could set the first TAB page via property node, when I run the code, so we always get the required result...


Anyone who could explain how a graph works in this example?


Thanks very much!

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Message 3 of 4

Rethinking this scenario again, I think the user event solution will be just good. Actually this bug is only a problem, when I have only a prototype VI like the example what I posted. When I will use my final VI structure in my project, it will contain Event structure with state machine, so I mark the prev. post as solution, thanks...


ps.: but I am still interested what's going on behind the curtain, so why a graph behaves like this (I thought first this behaviour can be turned on and off by the "synchronous mode" property node or something called similar -now I do not have labview on this terminal to check it- , but it did not solve this "bug")....

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