This system is used to let two rotators rotate synchronous,the rotators just need to be controlled by frequency converter,The rotators can be operated together and spearately,this system has much advantage,such as high precision,high reliability,and high universality,easy operation,etc.it will collect the speed form rotary encoder all the time and the system will compare with the speed all the time,then the PLC will send the program to control the speed higher or lower to let these two speeds difference remain into the allowed error range.