Waveform Chart behaves oddly with Minimum Time property

[carlos_camargo]

Hi All!

I have a question about this waveform chart and its behavior with different inputs for XScale.Minimum property.  I definitely want to have this graphing with a timestamp as the x-axis.  However when I input an minimum that is anything above some very small value, the charts stop working.  Values don't plot and the chart behaves badly, with the x-axis range scale flickering across values oddly.

The example I am posting is from the built-in examples "Waveform Chart Data Types and Update Modes.vi".  I removed all the irrelevant parts and added bits so the working and non-working states can be easily examined.  Just select the radio button and that will be set as the x-minimum when you press the Run arrow and then the graphs will then get data plotted to them.

What I would like to be able to do is set the start time for when data collection starts (in my real application).  Am I just misunderstanding the XScale.Minimum property?  Why do some values work but not others (current time)?

[thols · Accepted solution]

If you change the data type to a waveform you can set the timestamp for the data. See my modified VI.

[carlos_camargo]

Thank you very much for your solution.  I like how you handled the data and your example of t0 usage is something I didn't understand before.  After examining your example and experimenting more with what I was doing, it appears the magic trick was to zero the history data at the outset, before entering the loop.  After doing that to my example, it also works.  Yours works even if I don't clear the history (with some jankiness between restart times, which is probably expected) so I will most likely follow your implementation in my code.

Thanks again!

 C