Plot Visibility Not Working in LabVIEW Chart Legend

Updated Jan 12, 2023

Reported In

Software

  • LabVIEW

Issue Details

I have a chart that has over 256 plots in it. I want to select which plots are visible by using the legend to select the check box next to the plot number or name. However, I have found that if I choose one of my plots that is over the index of 256, it does not check the box or show the desired information, and a different plot shows up in the chart. What is happening and how do I fix it?
 

Solution

While this is a known limitation of the legend, you can programmatically set the visibility of charts larger than index 256 using LabVIEW property nodes. 
  1. Right click on the chart and go to Create»Property Node»Active Plot
  2. Drop the Property Node on the block diagram
  3. Expand the Property Node by hovering over it with the mouse and dragging down the blue dot that appears on the bottom 
  4. Click on the new box and select Visible
  5. Right click on the property node and select Change All to Write

You can now assign the plot you would like to make visible to the active plot property and set the visibility to true. The final property node configuration can be shown in the code snippet below:

 

 

Additional Information

The Visibility check box feature of the chart legend in LabVIEW has a known limitation of 256 elements. While a chart may have many more available plots, the legend was built on an unsigned 8-bit integer structure, which rolls over at an index of 256 elements. This means that selecting the Visibility check mark for a chart at index X, where X is higher than 256, will actually activate the chart of index X-256. For instance, checking plot 276 will actually turn on plot 20.

 

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