Can I add limit lines on my front-panel Waveform Chart?

[AdamS]

I have a chart plotting weight measurements from a scale... the data goes to a chart on my front-panel. I have some "LED's" that go on when the data point is outside the limits, but I'd like to have some lines that represent these limits on the graph. Any ideas?

[becktho]

Hi AdamS

That's not so difficult.

If you are using a chart-control, you have to bundle the values (see attachment) to display multiple signals. To do the same using a graph-control, you have to build an array with the values.

Hope this helps.

Thomas

[chilly_charly]

This is something that can be done easily with cursors. Unfortunately, cursors are not available with charts. But you could adapt a waveform graph to your need. The attached example is an illustration of what can be done.

Message Edited by chilly charly on 04-22-2005 07:09 AM

Message Edited by chilly charly on 04-22-2005 07:17 AM

[Odd_Modem]

Here is a good example

\LabVIEW 7.1\examples\measure\maxmpl.llb\Limit Testing Measurement.vi

[AdamS]

Do you have this example in 7.0?

Sorry for the trouble... I really appreciate the help.

[AdamS]

Hey, that worked great! Easy. One follow up question, though...

Can I change the color of the lines on the chart? We have spec limits, so-called "upper and lower green", "upper and lower yellow", as dictated by good 'ol procedure. I'd like my lines to be these same colors. Whattayathink?

Thanks a million!

[becktho]

Hi

This is also very easy. You have two possibilities:

1. Right-click the line on the plot legend of the control to set the color during development (see frontpanel.jpg).

2. Create a property-node on the blockdiagram, set the active plot and the color (for this you can use the color-box constant / see blockdiagram.jpg).

Hope this helps.

Thomas

[AdamS]

That worked great... should have figured it would be that easy.

I have one last question (maybe)... I've been trying to figure this out but to no avail. How do I clear the chart at the beginning of every run? Is there a property node that can do this or is it even simpler than that?

Once again, thanks. You help has been much appreciated.

[chilly_charly]

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AdamS wrote...Is there a property node that can do this or is it even simpler than that?...

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You can use the "History data" property node, and write an empty array to it.

CC