Servo motor encoder is installed on the servo motor to measure the position of the magnetic pole and the servo motor angle and speed of a sensor, from the different physical medium, servo motor encoder can be divided into photoelectric encoder and magnetoelectric encoder, in addition to the resolver is also a special servo encoder, the market is basically used photoelectric encoder, but the magnetoelectric encoder as a rising star, has the characteristics of reliability, cheap, anti-pollution, etc., there is a tendency to catch up with the photoelectric encoder.