Encoders are usually divided into incremental and absolute types. They have the biggest difference: In the case of an incremental encoder, the position is determined by the number of pulses calculated from the zero mark, and the position of an absolute encoder is determined by the reading of the output code. In a circle, the output code reading of each position is unique; therefore, when the power is turned off, the absolute encoder will not be separated from the actual position. If you turn on the power again, the position reading is still valid; unlike incremental encoders, it is necessary to look for the zero mark.