TDMS file viewer > waveform subset > min max

[zilla]

I would like to use the TDMS file viewer to plot my large waveform then extract a waveform subset, then use a Min/Max vi to get my data points.

My attempts at this have been some what successful but when I get down into a smaller waveform subset I don’t get the data points that would be expected.

Thanks for any tips on the correct way to get this done.

[Brian_K.]

Hi zilla,

When you say that you do not get the data points you expect, what exactly are you getting (any patterns or clues to help us debug)?  How small are your subsets getting?  I have posted how I would acheive a min/max query on a TDMS file.  If you test your data with it do you get any better results?

[Brian_K.]

Sorry, I forgot to attach a picture for the pre-LV 8.2 users.  I hope that helps.

[zilla]

Brian, Thanks for your reply,

I figured out what I was doing wrong. I wanted the user to be able to use the Graph Palette "zoom control" to select an area to be the waveform subset.  The vi would then use a Prop Node tied to the Main Waveform to extract the XScale.Range. From the XScale.Range I Unbundle the Maximum and Start values.  I was feeding the Get Waveform Subset.vi these values, but found out that "Duration" should be fed the difference between Maximum and Start. Makes good sense now.

Happy Trails...