Absolute Encoder Scaling

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I have a Sick wire draw absolute encoder  (Part # BCG13-I1BM0599) The given information that I have is as follows:

- Wire Draw Absolute Encoder (wire draw mechanism and encoder together) - .001 resolution

- Encoder Total Resolution - 1073741824 counts

- Counts per revolution - 262144

- Max pull out length - 5.2 meters

  I need to scale this down to a span of 0-150 inches. If you have any advice, I would very much appreciate it as I am at my wits end. Thanks.

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I'm assuming this will be wired to a Micro- or CompactLogix encoder input?

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well it has to be connected to something. what is the device or program that reads the encode value over the ethernet? you need to add scaling function there.

two readings at two different and precisely measured lengths.



length L1, reading R1

length L2, reading R2.

then apply linear scaling.


Linear Scaling.jpg

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Hi James !

The good news is that your wire-draw encoder is a really good device compared to how most wire-draw encoders work, with simple voltage divider and potentiometer.

Yours has one of SICK's EtherNet/IP absolute encoders bolted to it.   That looks nearly identical to the Allen-Bradley 842E because it is.

To scale your actual mechanical stroke as installed, Panic Mode is exactly right:  you need to capture the encoder counts at zero inches of your mechanism, and at 150 inches of your mechanism, and do a straight linear equation.

You can get some insight into the encoder by converting those counts into hex:

1073741824 = 0x4000_0000 = half of the maximum value of a 32-bit signed integer

262144 = 0x4_0000 = 1/4096 of 0x4000_0000, so it supports up to 4096 turns.


The important specification that I got from the SICK website is that while the total wire draw is 5.2 meters for that model, the wire draw *per encoder revolution* is 385 mm.

150 inches is 3810 mm exactly.

3810 / 385 x 262144 = 2594204.26 counts for the full 0-150 inch stroke, or about 17294.7 counts per inch.



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Thanks for all the help fellas. We got working perfectly now.

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