Abstract: A vehicle control unit for a short-distance traffic system is disclosed wherein a plurality of vehicles are controlled from a center. Each vehicle carries at least two on-board computers each of which process the control commands coming from the center to provide commands to on-board units and compiles telegrams to the center concerning the condition, location and speed of the vehicle in response to information from the on-board units. Both computers perform the necessary processing independently of each other. A comparator ensures that commands to the on-board units and the compiled telegrams are not sent until this information is received in identical form from both computers. Each computer delivers life signals at regular intervals to an associated emergency brake circuit, which initiate emergency braking if life signals from the associated one of the computers are not received within a given period of time.

Abstract: The specification discloses a system for protected data transmission between a control center and a plurality of track-bound vehicles. The data is not acknowledged as correct until it is contained in two successive data messages which are compared. The comparison indicates whether the difference between the two successive messages is within predetermined limits.