Abstract: A combination changing method is used in an access control system which includes one or more keys encoded at a central console with a function information code, a key identification information code, an operation select information code and a two-field key combination information code and one or more locks having at least one memory level in which a lock identification information code and a lock combination information code are stored. A key is initially inserted into a selected lock and the data from the key is transferred to the lock. The lock identification information code is first compared with the key identification information code. If there is no correspondence, power to the lock is turned off for a set period of time. If the identification information codes correspond, a test field of the key combination information code is compared with the lock combination information code. If these correspond, the lock opens.

Abstract: A security system includes a central console, one or more locks, one or more console coded programmers to transport data in a secure manner between the central console and one or more of the locks and one or more enabling programmers to enable the lock to operate upon insertion of a special key into the lock. The central console encodes combination codes from its memory which correspond to combination codes stored in a memory level of one or more locks in the system. The encoding results in a first modifier code which is combined with other information to form a programmer data word. The central console processor next scrambles and transfers the resultant coded data word to a console coded programmer. The console coded programmer stores the coded data word in its memory until a communication link is established between a lock and the programmer. Thereafter, the console coded programmer first unscrambles the coded data word and then further encodes the first modifier code to obtain a second modifier code.