The activation unit includes a lock (ZS) with a bolt (R) in a leaf (TB). A bolt pocket (RT) is allocated to the bolt and a locking stop which locking function can be abolished electrically by a control unit of the alarm when the alarm is ready for activation. A switching unit (S) can only be operated when the locking function of the locking stop is abolished. The switching unit is used for alarm activation. The locking stop is formed as a bolt stop (RS) which is arranged at the locking pocket in such manner to allow the bolt to be moved into the bolt pocket using one key turn but prevents the bolt of further movement. A further movement of the bolt which will activate the alarm is only allowed when the locking function of the bolt stop is abolished by the control unit which involves comparing codes.
