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Topic-icon Encoder CPR

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3 years 3 months ago #29532286 by Myzhar
Encoder CPR was created by Myzhar
Hello,
I'm configuring my new SDC2130 dual motor controller and I would like to understand which is the correct value to use for the encoder parameter "Pulse/Rev" .

I use capacitive encoders ( www.cui.com/product/resource/amt10-v.pdf ) that can be programmed such to have 48 PPR up to 2048 PPR and I have not understood if "Pulse/Rev" is the nominal PPR value or the effective QEI value (PPRx4).

According to the reply, which PPR do you suggest me to use? I think that 2048 should be the optimal value.

Thank you in advance
Walter

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3 years 3 months ago #29532291 by blake
Replied by blake on topic Encoder CPR
Hello Walter

According to the datasheet you linked, the PPR resolution is adjustable with the DIP switches on the encoder. So, it simply depends on what resolution your application requires. You'll get greater accuracy at higher resolution, so if you are not needing to operate at >7500RPM then I would recommend 2048 PPR.

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3 years 3 months ago #29532292 by Myzhar
Replied by Myzhar on topic Encoder CPR
Thank you Blake...

About the value to use as parameter? 2048 or 8192 (QEI counts)?

I think that 2048 is the right value since RoboRun+ accepts values up to 5000...

Walt

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3 years 3 months ago #29532293 by blake
Replied by blake on topic Encoder CPR
You will use 2048 PPR.

The QEI counts value (8192) is a completely separate parameter also known as counts per revolution or CPR. This refers to the number of rising and falling edges of each of the individual pulses. Since the quadrature encoder has two pulse signals, A and B, this means that each pulse will have a total of 4 edges. Therefore CPR = 4*PPR.
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3 years 3 months ago #29532294 by Myzhar
Replied by Myzhar on topic Encoder CPR
I know... but since RoboRun+ calls the parameter "Pulse/rev" I was confusing "Pulse" and "Count" terms.

So the correct value to use is 2048.

Well... now it's time to tune the PID :)

THANK YOU VERY MUCH
Walt
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3 years 3 months ago #29532295 by blake
Replied by blake on topic Encoder CPR
You're welcome, let us know if you have any other questions

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