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How-can-I-collect-both-differential-and-single-ended-voltage

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I found this topic from back in 2007.

https://forums.ni.com/t5/LabVIEW/How-can-I-collect-both-differential-and-single-ended-voltage/m-p/61...

Has any way been developed to take a single ended and multiple differential measurements within a short period of time??  I don't want to say simultaneously because I know that is a different DAQ Card.  I'm using a PXI6229.  I'm measuring four differential voltages ( "x" vac@400hz) and want to compare the phases of each to my single ended ref voltage of 5 vac@400hz.  I think I want to acquire them (all 5 voltages) as "simultaneously" as I can.  I have no problem reading the 4 diff voltages..and no problem reading the SE ref voltage separately, its just getting them at the same time that's the trouble.

Not using Signal Express..

 

Thanks..

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It may depend on the device you are using but I would try just tying the ground of the SE to the negative input of a channel configured for differential... possibly through a 1 M-ohm resistor if isolation is a concern.

 

Ben

Retired Senior Automation Systems Architect with Data Science Automation LabVIEW Champion Knight of NI and Prepper LinkedIn Profile YouTube Channel
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I tried that and it gives really bazar waveforms.  Could you provide an example where I "configure","start" and "read" the channels as soon as possible in my created vi??  I think if I "read" the differential channels then the single channels as close as possible in a single vi that may work.  Right now I read differential channels in one subvi then read the single ended channels in another subvi.  I think this delay from one sub vi to another is long enough my phase calculations is wrong.

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Accepted by topic author Clint1000

I was suggesting you ONLY have a single task reading all channels as differential including the SE channel.

 

You can try it out in MAX by creating a task that has all differential channles and work with your wiring for the SE channel and tie the "-" side of the Diff. channel to ground or AI return.

 

Ben

Retired Senior Automation Systems Architect with Data Science Automation LabVIEW Champion Knight of NI and Prepper LinkedIn Profile YouTube Channel
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That worked!!  Thanks..

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