The most popular variation of the electromechanical castle is equipped with a special digital panel, similar to the one that the intercom is equipped. On this panel there are buttons with numbering from 0 to 9. The castle itself, as a rule, is encoded by a certain combination of numbers. In the case of the correct set of combination and the use of the physical key, the lock is also triggered, therefore, it opens. If the sequence of introduction of the combination is incorrect or the key is not used when unlocking, the castle, of course, does not work. In the event that there is no power of the lock, or the battery is discharged, in this case only one key is enough to unlock the door.