The spindle encoder on CNC machine tools generally has two functions: speed feedback and position feedback. Generally, CNC machine tools need thread processing. Each rotation of feed processing requires interpolation between the feed shaft and the spindle speed. Therefore, feedback speed and rotation direction are needed. When the tool is changed on the machining center, the spindle will stop at the fixed position every time by feeding back one revolution pulse signal. Above as long as there is a pulse signal encoder can. For example, when CS machining is carried out on several cars of inclined lathe bed, two encoders are generally used, one is to realize speed feedback at the back of motor, the other is to realize any angle position feedback of spindle on the spindle.