Waveform chart sweep rate

[jbphili]

I inherited this application and am a beginner to LabView. I am hoping someone can give me some idea about the problem I am having.

The application originally display data using a set of waveform charts (sweep plot). I need to add a new set of charts that do the identical thing with slightly different data. Most of the charts are working great, except one. Somehow this one chart is sweeping twice as fast as the others. My new charts all started as clones of the original charts, so I don't understand why one is not working like the others. I didn't see any properties that appear to affect the sweep rate in my vi either.

I'd appreciate some starting point to look what can be causing the faster sweep rate.

Thank you very much.

[garrettmarsh · Accepted solution]

You will probably need to post code or screenshots to get some useful responses.

That said, there could be a couple things at play here. The chart history length sets how much data is stored, and if that length is reduced, the chart will appear to sweep faster. It is set at edit time from the chart's right-click menu and would not be apparent from looking at the block diagram.

Also, the chart is updated each time a value is written to its terminal so it could be updating faster if it is in a loop with shorter delay (for example). This is where it would help to see the BD.

Finally, since you are new to LabVIEW, I would take a look at this if you haven't already:

https://www.ni.com/docs/en-US/bundle/labview/page/types-of-graphs-and-charts.html

[jbphili]

You are right. The problem is that that particular waveform has buffer size half of everyone else. After changing the buffer size and the x-axis scale to match the others it is working as expected.

Now the mystery is how it got set differently to begin with, since it was copied off existing waveform chart.

Thanks.