encoder resolution

John Morris · Jan 20, 2017

Good Morning all.

Pick your brains please?

1769-L30ER

Haven't chosen a module yet. Rep said to choose encoder first. So in the process of choosing an encoder the question of resolution came up

Tolerance is 1/8 inch +/- of target.

Resolution options range from 0001 to 10,000, with an adder after 2,000.

In this case how much is too much.

Our chosen redundancy is laser measurement.

Please advise

Thank you for your time and attention.

John Morris · Jan 20, 2017

cookswim · Jan 20, 2017

We'll (you'll) need to know a bit more information about how mechanics are setup in order to help with picking the correct encoder resolution.

Important bits to know would be: linear or rotary system, linear or rotary encoder, gear ratios between target and encoder, and probably some other stuff I can't think of right now.

You eventually have to calculate out what one encoder tick represents in your real world space, then you can properly select the encoder resolution.

ndzied1 · Jan 20, 2017

I think this would be a good resource for you to look at that will help a lot with understanding encoders and how to select them.
https://www.dynapar.com/uploadedFiles/Products/Danaher_Encoder_Handbook.pdf

John Morris · Jan 20, 2017

Thank you norm

That was a tremendous help.

kamenges · Jan 20, 2017

Since you have a processor with built-in Ethernet/IP, if you are looking at any combination of resolution and speed that puts you above about 50 edges per second OR you are looking at A-quad-B encoders I would just go with an Ethernet/IP encoder. The cost of an A-quad-B encoder and a counter module would buy you an Ethernet/IP device that is easier to use.

Keith

Peter Nachtwey · Jan 21, 2017

A lot depends on the dynamics of the application. In general I recommend getting the most resolution possible that doesn't exceed the counters maximum count rate. Higher resolution makes it possible to estimate the velocity and acceleration more accurately and this allows better control.

Aabeck · Jan 21, 2017

I recently replaced an encoder to HSCE card setup on a hoist X axis to a Banner laser system to an analog input. Cost about $400 total (there was an unused analog input already).
There is now about 6 times the resolution over the encoder and the laser doesn't need "homed" every power-up like the encoder did. They get much more precise positioning than the encoder could ever hope for. (Rated at 1/2mm accuracy over 25 meter range)

encoder resolution

John Morris

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John Morris

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cookswim

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ndzied1

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John Morris

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Peter Nachtwey

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Aabeck

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