Abstract: A sliding door (B) that is operated with a door drive is moved with the aid of a lever arm (A) that is driven by a motor (M) via a gear. The end positions of the door, as well as two intermediate positions, are detected with mechanical switches (C) that are actuated by a cam disk (K). The mechanical switches (C) form a redundant safety system and, if necessary, can be omitted. A non-contacting sensor (S) is used independent of the mechanical switches (C). For the purpose of detecting the position, the sensor can fully replace the mechanical switches (C) and the cam disk (K) for actuating these switches. With the aid of a transmitting wheel (D) and the sensor (S), it is possible to draw a conclusion relating to the rotational speed as well as the door position. A central data processing unit (CPU) permits the control and adjustment of the door drive. A diagnostic evaluation of the door drive with respect to required maintenance operations is furthermore possible with the central data processing unit (CPU).