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Slow Velocity Measurement Using cFP QUAD-510

I want to use the cFP QUAD-510 Module with a 1024 Count Per Revolution Quadrature Encoder to get velocity, direction, and placement of a rotating shaft. The shaft is a VERY SLOW ROTATING SHAFT, about 1 revolution per 7 seconds, or .143 rps. The encoder frequency is 1024 X .143 which comes to 143.432 Hz. I have two questions:

 

1. Since the velocity counter registers in the QUAD-510 are fixed in microsecond references, will I get a meaningful resolution out of the registers with an encoder freq. of 143Hz?

 

2. Is 143Hz too slow for the QUAD-510 and should I just change over to an absolute encoder with a DIO Module and do my own velocity calculations with loops and longer time bases?

 

I know the quadrature will work for placement and direction. But I am not sure if this is the right application for velocity.

Ron Kocol
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Ron-

Due to how slow your encoder is running, I can’t guaranty the accuracy of the velocity readings from the counter references.  A better way to do this would be to simply take the derivative of your position (dx/dt).  This way it will be as accurate as possible.
Regards,

Mike S
NI AE
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