As an element of electronic protection systems, an access control system perfectly supplements an intrusion detection system. A modern access control system must also limit unauthorised persons’ access to certain locations on the premises when authorised persons are present in the protected zone. This is a solution alternative to traditional mechanical access control systems based on ordinary keys. The functionality of microprocessor-based controllers is much more extensive than even extended “master key” type systems. Dedicated software provides administrators with a fast and simple method of selecting persons included in the system, creating schedules of passes and ensuring access. This is one of the reasons why investors so willingly take advantage of their capabilities.