Encoders can be divided into absolute type encoder, brush (contact) encoder, channel encode, chronometric encoder, command encoder, digital position encoder, digital shaft encoder, digital voltage encoder, diode matrix encoder, error signal encoder, experimental digital television encoder, incremental encoder, inductive encoder, linear angle encoder, key encoder, matrix encoder, optical position encoder, optical rotary encoder, phase encoder, photoelectric encoder, priority encoder, quantitative encoder, reading encoder, shaft-position encoder, source encoder , Space encoder, test encoder. But there are two most commonly used: absolute encoder and incremental encoder