Take all max and min points

[Luis Monteiro]

I have a graph XY who make an acquisition of two signals, force and position in degrees. The board is a DAC Card 1200. I would like analyse only all max and min points, and ignore all others points. For that, I need take all max and min points separately, in form to put those points in a file (report). In the annexed file you can see the respective curve, the cycle is, first go the 0º to 270º (trace the up curve) and then go the 270 to 0º (trace the down curve). I need take separately the first max, them all maximums points, and all minimums of the up curve (0º to 270º). Them, the minimum point, and then all minimums and maximums points of the down curve (270º to 0º).

[unclebump]

Here is something I used to find when tools were changed on a metal cutting machine. It uses LABVIEW 7.0 and the time domain differential and compression express vi's. The spikes in the time domain differential result are the points where the curves change slope. I had to use the compression vi to filter some spikes out of the data. The peak detect vi's will offset the peaks a little from where they are in the original curve. I used the peak detect output array to give me a search window in the original waveform. Then plotted the peaks on a transparent graph laying on top of the original.

[Luis Monteiro]

Sorry but I don’t have labview 7.0, my version is 6i and 6.1.
Can you convert it? I appreciate that.

[unclebump]

Here are the vi's in 6.1 format. It looks like it is working ok but I had to adjust the threshold values to find the peaks properly. Open the largest vi file. This vi finds the minimum points in cyclic data that vary as a function of time. A regular limit detection vi won't work.

[Luis Monteiro]

Thanks for your help, with your program I can take a good idea to make my program. It was not easy to understand your program initially, but then was a great help. Thanks for all.