xy graph or waveform?

[Ya-hoo]

If I have 2 analog signals acquired, such as pressure and temperature. I'd like to display a real time measurement on the screen. The test may run for many hours or a few minutes, we'd like to track back the display to the start point. We could either display the measurement within certain time range or in the whole time range? That means the X scale could be changed during program running. How can I do it?

Which one is better for my application, XY graph or waveform?

Any example code I can find?

Thanks in advance.

[Robert M]

Hello Ya-hoo,

I would recommend using a chart. You can set the history length to as many points as you want to see. You can turn the x-axis scroll bar on and off programmatically, letting you see the whole data set, or any particular range. You can display your pressure and temperature as separate plots on the same chart.

If none of these suggestions help, or if I�m not correctly understanding your issue, please reply with comments or answers to the discussion above and any additional information that may help, and I�ll be happy to look further into it.

Have a nice day!

Robert Mortensen
Applications Engineer
National Instruments

[Ya-hoo]

Thanks Robert.

How can I set more than one Y scales in one chart?

Thank you.

[Ya-hoo]

Hi Robert,

The thing is that I can't input culster to property node of that chart if the chart has more than one plots. I chose value property for that input.

The chart is in main vi and get the data to be displayed in subvi. So the chart's reference was passed to subvi.

Any suggestion?

Thanks.

[Jeremy_L]

Hi,

Actually in order to be able to wire a cluster to the chart, the chart itself must be represented as a cluster instead of an array. To do this, create your cluster by bundling up the values/signals you want. Then, delete the old waveform chart and wire the cluster to a fresh new Waveform chart. You should see the chart color icon change from orange to brown. Now, create a property node of this new chart. The value property should now allow you to pass in clusters, thus allowing you to make a multi-plot chart using property nodes. Hope this helps!

PS - You can see how clusters are used with Charts by opening up the example program Charts.vi, which is found in the NI Example Finder.

Jeremy L.
National Instruments