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More information about Pulse Measurements VI

Hi to everybody I post this entry because recently I have started to use the Pulse Measurement VI to inspect PWM waveforms, but a colleague left the percent level settings -> Method of the VI in auto select and it causes that some inspections failed, I tried to change this setting to histogram and the failure dissapeared, after I discovered that the Auto select setting was choosing Peak as Method for Percent Level and it seemes to be the cause of failure.

 

I am attaching a sample of a waveform with the failure. I would like to know more about how to configure of the best way to parameters of the VI and how the VI determines which method to use as well as which is the histogram referred whe I use this setting.

 

For my measurements the shape has the trend of a square wave with peaks on the edges sometimes but I am handling this with a hysteresis band to flat the edges.

 

Thanks in advance

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Hi AYanez,

 

why do you need so many histogram bins?

With just 16 bins no warning is given…

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
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Hi GerdW, one of my colleagues left the parameters of this way, I dont have clear about what magnitude is being parametrized with the histogram, could you explain me more about the considerations when you use one or another method?

 

Thanks in advance for your attention

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I looked at your code, and didn't recognize the Pulse Measurements function that you were using (I'd never tried to do this in my own work).  So I right-clicked the function, chose "Help" from the drop-down menu, and read what this function does, how it works, what "Histogram" means, etc.  I have enough "common sense" + "experience with signals" and familiarity with analyzing signals that I was able to understand the Help description, including how the Histogram Algorithm is supposed to function, and what the parameters mean.

 

Have you done this?  What part don't you understand?  Have you tried taking a waveform (such as the one you attached) and "playing" with the function, varying parameters and seeing what happens (to "teach yourself" how it works)?

 

If you are still having problems, you might find a colleague or a student with some electrical engineering experience and spend 15-30 minutes talking with them, particularly if you have set up the "Experiment" I suggested in the previous paragraph.  Sometimes two heads thinking about a problem together (rather than by exchanging questions and answers on a Forum) can lead to rapid understanding and comprehension.  It's my favorite way to find bugs in my own code ("Oh, no, Bob, you code doesn't have bugs, does it?"  "Never".  "What, never?"  "Well, hardly ever ...")

 

Bob "HMS" Schor

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