Persistant graph trace

[BartSchroder]

Hello,

does anyone know how to make a trace on a Labview Graph persistant. One way would be to find a way to avoid the deletion of the trace when the graph is redrawn.

I have been able to do this witha bit map graph, but the management overhead is serious, and the graph is slower than a native graph.

The idea here is to be able to show a visual history of previous plots - much like you can see on some scopes.

Any help very welcome,

Bart Schroder

[Louis Manfredi]

I've needed to do the same thing. Only way I've found to do it is to save the data that I want to keep-- For example by passing it to a shift register in the for or while loop-- and then bundling this old data with the new data to which I want to make the comparison.

Perhaps there's a more elegant solution, but this method is probably more efficient than using a bit map, and I suspect handles things like rescaling of the graph more gracefully too.

(To get really complicated-- if you use Max & Min function from the comparison menu to generate two historical traces, on the minimum of each time sample from all past traces , and one the maximum of each from all time, and then play around with the "Fill Baseline" plot properties for these traces, you can get something that looks very much like the display on an old anlog storage scope...)

Hope this helps...

[BartSchroder]

Thanks Loius, I'll give it a try!

Bart Schroder

[JackHamilton]

Hey a Chart with "Sweep" option enabled shows the previous trace until it's replaced by the new data point-by-point.

This is a quicker way...