An automatic control system for controlling the operation of a sliding door system employs an electric motor for driving the sliding door system. An encoder is mounted to the shaft of the motor for generating signals which are decoded to detect the operational position of the sliding door system. A clock paced sequential logic circuit produces speed and directions signals in accordance with the detected operational position to control the speed and direction of the electric motor. Means are provided for recording the last stop position and slowing the sliding door system prior to reaching the last stop position. Safety means are provided to de-energize the motor in the event of malfunction of the motor speed control. The system also includes a reduced opening stop feature and a means for automatically establishing a sliding door reference position.