The invention relates to a central locking installation for a motor vehicle, having a controller and a remote actuating device, which installation is provided with at least one transmitter, operating as a key, and one receiver, operating as a lock, upon actuation of the transmitter for the purpose of locking or unlocking the door locks, a code word and a transmitter recognition signal are transmitted, and whereupon a control pulse is transmitted by the receiver to the controller which causes the locking or unlocking process. The receiver contains a coding device, by means of which a transmitter allocation is made according to the transmitter recognition signal.
Such a central locking installation is disclosed in German Patent Specification 3,244,049. In this case, a quantity of defined, different code words (stock of code words) are stored in the transmitter and in the receiver, which for their part are arranged in a sequence. When a control element is actuated, the transmitter transmits one of these code words, to be precise switching on through the sequence, starting with the first code word. A decoding device in the receiver correspondingly converts a received code word into an unlocking signal and supplies this to the controller. If the stock of code words is exhausted, a start is made at the first code word again, cyclically. If an embodiment having a plurality of transmitters is involved, but having different quantities of code words from transmitter to transmitter, the decoding device for processing these code words is equipped with a plurality of decoding channels corresponding to the number of transmitters. When the transmitter is actuated, a fixedly set recognition signal (transmitter recognition signal), depending on the transmitter, is transmitted which differs from the recognition signals of other transmitters and switches on the corresponding decoding channel in the receiver.
In the known central locking installation, both the transmitter recognition signal and the number of decoding channels, and hence the number of transmitters used in the central locking installation, must be known in advance. These data must have been set at the manufacturer's works, for example by programming. The user is thus confined to a predetermined number of keys from the start.