How do you clear the chart in an AI Waveform Scan VI upon program start?

[marshri]

I am using a waveform scan vi in a program. The output of the vi is set to "Waveform". What I want to do is have the program automaticly clear the waveform chart each time the program starts. Currently I must start the program, right click on the chart and select clear. I have attempted to use the chart history property node, which I assumed is the correct path to take but so far my attempts have been unsuccessful.

[Jonnie_5]

Are you wiring an empty array to the history property node?

See ex.

[marshri]

I looked at you example and gave it a try. Did not work. I tried using the build waveform from the waveform tools and building an empty waveform, did not work. If I look at the "Context Help" I get this description. Property: History Data History ( 2-D array of Waveform ). I would assume that I could build an empty 2-D waveform with the build waveform tools and wire it to the History Property Node. I was unsuccessful in getting it 2-D. I am going to attemp to attach an example file of my problem. Keep in mind that this is just part of a program that does work, just not the part about clearing the chart at program start. Thanks for your help and input. Us greenhorns need all the help we can get.

Ricky

[Jonnie_5]

Ahhh, waveforms... These got better in LV 7 I hear.

Will this do it?

[marshri]

After looking at your latest suggestion, I thought mmmm maybe this might do it. So I tried it this morning. It did not work. The chart just continued to display the values at the time the program was stopped. Ahh not to dispare, I do not give up easly, and in trying some other things, I kept looking for a way to make a 2D empty Waveform arry. I finally did it. The answer was right there in a VI that I have never used. Reshape Array. See the attached file to see what I did. My boss is going to be stoked! Because he is pretty good with LabView and it has had him a bit stumped. Anyway thanks for all your suggestions and help.

[Liz F]

Nice job!

That works great. I've run into this issue several times in the past, and I just wanted to show you a slightly different, slightly more streamlined solution as well. I attached two files, the first for LV 6.1 and the second for LV 6.0.

Have a great weekend!

Liz Fausak
Applications Engineer
National Instruments

[marshri]

Thank you for the example. Your way is much cleaner. This is one solution I will not forget.