XY graph does not connect dots

[jand]

In LabView 7.0 Express I am generating a graph by taking voltage and current measurements from an instrument.  However, whenever it graphs a point, it erases the previous data point.  What I would like is for it to keep all data points and connect them with a line.  How can I  make this a reality?

[Dennis_Knutson]

You are seeing expected behavior. An XY or waveform graph does not maintain a history. A chart does. An XY or waveform graph is designed to display data when the acquisition is complete and you have an array of point. You can use the shipping example called XY Chart or use the Express XY Graph. The Express VI uses a local variable to store the last data points and then append the new ones.

[jand]

Thank you.

-jand

[mikeporter]

There is a way to have the graphing functionality of an XY plot and the memory of a chart, but you have to program it yourself. Attached is an example I made for someone else. I shows how to build the "memory" for an XY plot. It actually does a bit more than you need in that each time you press the new plot button a separate plot is created, but the important thing is the concepts behind it.

Note that the points sort of dance around the plot area because the X and Y values are derived from random number generators.

Mike...

Message Edited by mikeporter on 07-13-2007 08:59 PM