Mask & Limit Testing Express vi

[Schwede]

Hello, i have a problem with the Mask & Limit Testing vi. I want to connect the upper and lower limits at the terminals outside the vi. The limits are signals like this: 0            10 200        30 30000    200 The first column is the time in ms the second for example the length in mm. How must i connect this limit data? greetings Schwede

[JeffBoettcher]

The limits are defined by a waveform.  A waveform consists of a t0, dt, and array of evenly spaced datapoints, each separated by dt (or dx if you don't like time).  🙂

When you define your data points on the Define Signal dialog, there is a timing section in the lower right as well.  The data points you specify, combined with the dX value under the timing section, are used to interpolate waveform data.

If you need to change your upper / lower limits programmatically, you can use the Create Continuous Mask.vi

C:\Program Files\National Instruments\LabVIEW 8.0\vi.lib\measure\mamon.llb\Create Continuous Mask.vi

To generate this mask yourself.  This VI is not in the palettes and doesn't have the typical help detail, but given the information I've written here, and its inputs and outputs, its functionality should make sense.  You may need to take the elements of the "Limit" output cluster and use the Build Waveform function to create a waveform to send to the Dynamic Data input for the limit on the Express VI.

Message Edited by Support on 05-02-2006 09:22 AM

[unclebump]

I have a version of the limit and mask vi's based on using arrays and clusters as the inputs instead of waveforms. If you go deep down inside the mask and limit vi's, they use arrays and clusters. See this thread for the sample llb file.

http://forums.ni.com/ni/board/message?board.id=170&message.id=145767&query.id=105856#M145767

[Schwede]

Hello,

thankyou for your answers, but have someone an example for me that use teh Mask & Limit Testing EXPRESS VI and change the upper and lower limit from the frontpanel?

schwede

[JeffBoettcher]

This is what I tried to explain, I guess it got a little complicated, heh.  As always, a picture (or diagram) is worth a thousand words.  Hope this works out for you.  🙂

[Bob_Y.]

Are you trying to test the data to one limit, then to the second, then to the third?  Or are you trying to build two waveforms and then test to them?

The first is solved by setting up the limits as constants in the Express VI and then wiring in the constants.

The second is much more difficult as the waveforms need to match in dt and array length.  I think that can be accomplished easier than Jeff is doing it, but I would like a better idea before I spend the time to come up with an example.

So, several steps with constant levels or a single step with a complex level mask?

Thanks,
Bob Young