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Problem in acquireing sinusoidal waveform using ni-9215


I am using ni 9215 card for power and frequency analysis of single phase AC circuit (with the help of voltage and current transducer which provide 0-10V dc output for voltage 230V ac and 0-10V dc output for 0-5A AC).

Now when i am acquiring signal it is not a sinusoidal waveform. As i am new to LabVIEW please help me to get power and frequency of single phase ac.

If you have any example related to it, then it will be very helpful for me.



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Message 1 of 6

Attach the VI you have started with that is giving you problems.


There are a lot of DAQmx examples in the example finder.  Browse through there.

Message 2 of 6

Please find attached vi for frequency measurement.

Daq assistent 1 for voltage input from transducer of 415V ac to 0-10V dc

daq assistent 2 for current input from current transducer 500A ac to 0-10V dc


Four inputs given on AI 1+ AI1-

& AI 2+ AI2- of daq 9215 which is fitted on cDAQ 9171


Need your guidance...


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Message 3 of 6

Your VI attachment didn't make it into the message.

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Message 4 of 6
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Message 5 of 6

How are you running this VI?


You don't have a while loop around it, so it is only going to run once.  (Please don't tell me you are using the run continuously button which is only meant for debugging subVI's.)


Your DAQ assistant is set for N samples, and for 100 samples of a 1 kHz rate.  That means you get 1/10th of a second at a time.  And if you are rerunning this, that means it runs, collects data, stops, and restarts.  You have no continuous acquisition going on.


You also have 2 DAQ assistants in there which appear to be reading the same channel.  Even if they are different channels on the same device, you'll have problems because for most DAQ devices, one with throw an error once the other has already started running.  Just create one DAQ assistant with multiple channels.


Better yet, I suggest checking this out. Become a DAQ Guru: Learn 10 Functions in NI-DAQmx and Handle 80% of Your Data Acquisition Applicatio...


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