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how to calculate the phase difference between two square wave (acquired from two channel in one DAQ)

Hello everyone ,
 
 I need a quickly help that as below :
I am trying use PCI-6220 to acquired six signals from one rotation encoder (channel A, channel B,channel Z ,and their non-signals) .The encoder out signals will be square wave and 4000pulses per revolution. I set it rotation at 300rpm speed. I need show every square wave of six out channels in waveform and measure the A-B phase difference to check if the value is correct (designed value should be 90deg) .
I have no idea how to measure or calculate the phase difference of two square wave base on synchronizate to acquire these two square wave from two channel on the PCI-6620....
 
Anyone can give a idea how to calculate the phase difference with two square wave ?
 
Thank a lot and Thanks again...
 
Tim
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Message 1 of 11
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Tim,

Locate the rising edges of both A and B by sample array index numbers. Find the difference in index for successive samples of A. Find difference in index for an A edge and the next B edge. Divide by the difference in A. Result is fraction of period. To get phase in degrees multiply by 360.

Lynn
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Message 2 of 11
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Lynn,
 
Thank you for your response , But I have a little confuse on how to locate the rising edages of both A and B by sample array index numbers. can you give me a program that  demonstrate what you show me ...Please.
 
Thank you very much 
 
Tim 
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Message 3 of 11
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Tim,

What version of LV are you using?

Lynn
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Message 4 of 11
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Lynn,
 
   Labview8.2 full .
 
Thanks again
 
Tim
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Message 5 of 11
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Tim,

Here is a simple rising edge detector for one channel.

Lynn
Message 6 of 11
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Thank you very much !!!
 
Thanks again .
 
 
Tim
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Message 7 of 11
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hi, sorry to bother, but my labview version is 8.0, so i cant open this VI 😕

i wonder if you guys cant post the picture (jpeg or whatever) of this vi


thanks a lot


see'ya
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Message 8 of 11
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Here is an 8.0 version.

Lynn
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Message 9 of 11
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Hi Lynn,

 

Can you also add further for finding phase difference from two channels ? 

 

Thanks in anticipation.

 

 

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Message 10 of 11
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