Communication system for data transmission in a control device of a car

Communication system for data transmission in a control device of a car, in which the control device comprises a main unit (1) and a number of actuators (5, 6) connected thereto, and the main unit receives input signals from signal transmitters of the car, and drives the actuators on the basis thereof. Each actuator (5, 6) is connected to an associated slave unit (3, 4) which is disposed at a distance from the main unit (1). The main unit is connected by way of a serial communication connection (12, 13) to each slave unit, for the purpose of sending messages from the main unit to slave units. Each slave unit is assigned its own individual address for the slave unit and a group address applying for several slave units. An individual message contains an individual address and data. A group message contains a group address and data. Each slave unit has a data buffer. When a slave unit receives a first type of individual message with the individual address of the slave unit, the slave unit processes the data of the message immediately, in order to drive, in accordance with such data, one or more actuators belonging to the slave unit. When a slave unit receives a second type of individual message with the address of the slave unit, it stores the data of the message in the data buffer. When the slave unit receives a group message with a group address assigned to the slave unit, it releases the data stored in the data buffer and the slave unit and, in accordance with the data released from the data buffer and the data from the group message, drives one or more actuators belonging to the slave unit.