The SS series product that I.CH develops and manufactures is a closed-loop stepper motor control system. By feedback signal of the encoder, the motion of the stepper motor can be controlled in full closed-loop, which can eliminate the disadvantage in the open-loop control scheme, such as vibration in low frequency, large heat, out of step. And it has a certain overload capacity, which improves the utilization rate of torque and response of the system.