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Can't Seem to edge trigger with LabVIEW


I am seeking to trigger on Channel 0 between 2-3 Volts after Ethernet Reset VI runs . I would like to be able to view both channels 0 and 1. I am able to run the Measurement and Automation Explorer and get the desired results. However with my self created VI I cannot seem to get it to work. With immediate trigger the VI runs. But continues to run.  I have attached in a zip file picture of MAX, Front panel and Block diagram.


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Just for ease. Here are the screenshots.LabVIEW Block Diagram.PNGLabVIEW Front Panel.PNGNI-MAX SCOPE.PNG

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Message 2 of 9

Do not send screenshots of Front Panels and Block Diagrams!!!  Send the VIs, themselves.


Bob Schor 

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I see you are trying to view both channels 0 and 1 on the waveform graph. If you see the help document below under the "channels" input you will see a link to "Channel String Syntax." You will see that the syntax for reading channel 0 and channel 1 is "0,1".


niScope Help:

Can you further elaborate on what else you are trying to do? It looks like you are trying to create a trigger to start aquisition when the channel reaches a certain threshold? If this is the case I would recommend looking at one of NI's examples that does this. This can be found by going to help->find examples and following the path Hardware Input and Output->Modular Instruments->NI-SCOPE->Continuous Acquisition. You can see fetch forver, or fetch in chunks, as you could play with both to see their functionality.




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Yes I would like to trigger on chanel 0 with the negative going edge. This is an ethernet POE Voltage. This voltage is on the order of 55 volts.I am using a voltage divider to cut he voltage to half in interest of preserving my USB-5133.

 I would like to trigger early in its 55V collapse. With that happening on chanel 0

I would like to watch channel 1 which is 3.3v power to my microntroller. I want to meassure the time it takes to fall from  3.3v to 2.35 volts.    Is it possible to assign different voltage ranges and and offsets oto each channel?

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Message 6 of 9

It seems like you are on the right track. You are already using the analog reference trigger where you would specify channel 0, negative slope, and the trigger level threshold. When the analog value passes this threshold in the negative direction your aquisition will begin.


When the aquisition starts you could start the time (Tick Count or timestamp), and then record the time it takes until channel 1 falls to 2.35V. It doesn't sound like you want multiple triggers. The only way to do this would be to have two different tasks for each channel.




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Message 7 of 9

Would those tasks be wired in series (in other words one right after the other ie: inline)?

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Message 8 of 9

I was thinking that you would put them in the same task, but in series would essentially work the same way.



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