From 04:00 PM CDT – 08:00 PM CDT (09:00 PM UTC – 01:00 AM UTC) Tuesday, April 16, ni.com will undergo system upgrades that may result in temporary service interruption.

We appreciate your patience as we improve our online experience.

LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

Bug? Tab control breaks graph autoscale (+workaround)

I had this really annoying problem where two of my graphs did autoscale and the other two didn't... Although all the code and graph properties were exactly the same.
 
I finally figured it out...  The graphs are in a tab control. And only the graphs that are on top get autoscaling.  Labview 'forgets' to autoscale the other graphs when you show those other tabs. Even when I use a property node, I can't force the graphs to autoscale, unless they are on the showing tab.
 
Feels like a bug to me.... I can understand that graphs aren't updated/autoscaled when they're not shown for performance reasons... but I think the axis should then be updated/autoscaled as soon as the corresponding tab is shown.  And it certainly would be nice if the axis does autoscale when I explicitely ask for it using the property node...
 
 
Now that I understood the problem, I could also make a work-around.   I made a 'value changed' event for the tab control, and put the property node autoscale code in it.  That way, I ask for an autoscale right after showing the new tab page.  (See attached vi for example of the problem and work-around.)
 
The workaround works fine... but I think that this should be default built-in behaviour for graphs in tabs that have the autoscale enabled.
Message 1 of 3
(2,941 Views)
Hi Anthony,

This is a known issue that was partially fixed in LabVIEW 8, which you appear to be using. By partially, I mean that the behavior only persists when you update the value of your graph using a property node (either Value or Value Signaling). If you update the value using a direct wire connection to the graph terminal, or using a local variable, then the problem goes away. I would recommend using either of these methods, because they will fix your issue. Also, in general a direct wire connection or a local variable will greatly improve LabVIEW's efficiency in terms of updating the front panel. The only situation where this fails is if you need to update your graphs from inside a subVI using control references.

Because that last note is a very real situation, we will notify R&D of this matter so that they can investigate this further. Thanks for bringing this to our attention.
Jarrod S.
National Instruments
0 Kudos
Message 2 of 3
(2,918 Views)
I'm wondering if I'm having a similar problem.  I have a waveform chart with 6 y-axes on it.  They are in a tab control and the values are getting updated with a property node with control references.  Y-axes 2 through 6 autoscale properly.  Y-axis 1 will never go below 350 as the top unit but it will autoscale up from there.  I am using 8.0.1.  Is this the same issue?
 
Lee Jay
0 Kudos
Message 3 of 3
(2,881 Views)