Abstract: A device for limiting access to authorized users, for example, a vehicle access limiting device, includes a control device and a key device. The control device has memory wherein a preset user code and a preset secret code are stored. The key device has a transponder which includes a memory for storing the user code and the secret code transferred from the control device. The transponder emits the user code which has been encoded with the transferred secret code. The control device includes a comparison device which allows access only when the encoded user code emitted by the transponder agrees with preset information stored in the control device. The key device also includes a comparison device which prevents overwriting of the taught secret code unless it also receives the taught user code.

Abstract: The invention relates to a device for checking the user authorisation for access control devices, in particular locking devices for vehicles. The information emitted by the respective transponder (T1 . . . Tn) in key devices (B1 . . . Bn) in each case is compared to preset information, fixed by the secret code, in the control device, relevant for the respective key device (B1 . . . Bn), whereby(a) the relevant secret code for the respective key device (B1 . . . Bn) is stored, by learning it from the control device (A);(b) the information emitted by the respective transponder (T1 . . . Tn) comprises user code information encoded according to the learned secret code;(c) the control device (A) comprises a further memory means (M) in which the number of the key devices (B1 . . . Bn) taught by the control device (A) is stored; and(d) the key devices (B1 . . . Bn) comprise further memory means (M1 . . .