Definition: Encoders are the devices that change input signals into a coded format.
In our case encoders transform motor rotation into a digital or analog signal that can be used to control said motor.
Two types are linear and rotary encoders. Linear encoders encode motion in a path. Rotary encoders encode rotational motion.
Another break up of encoders are incremental and absolute encoders.
Incremental Encoders
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Absolute Encoders
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An encoder is a system that converts data's format.
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A holistic encoder takes into account the entire shape of the rotor instead of a small section is an optical encoder. This technology allows a high precise and accurate measurement.
https://www.anaheimautomation.com/manuals/forms/encoder-guide.php
https://electronicsdesk.com/encoders.html