Access Control Systems
Electronic access control uses computers (this might be a local controller or linked to a PC) to solve the limitations of mechanical locks and keys. A wide range of credentials can be used to replace mechanical keys. The electronic access control system grants access based on the credential presented. When access is granted, the door is unlocked for a predetermined time and the transaction is recorded. When access is refused, the door remains locked and the attempted access is recorded. The system will also monitor the door and alarm if the door is forced open or held open too long after being unlocked.
Access control system components
Various control system components
Components of an access control system include:
- An access control panel (also known as a controller)
- An access-controlled entry, such as a door, turnstile, parking gate, elevator, or other physical barrier
- A reader installed near the entry. (In cases where the exit is also controlled, a second reader is used on the opposite side of the entry.)
- Locking hardware, such as electric door strikes and electromagnetic locks
- A magnetic door switch for monitoring door position
- Request-to-exit (REX) devices for allowing egress. When a REX button is pushed, or the motion detector detects motion at the door, the door alarm is temporarily ignored while the door is opened. Exiting a door without having to electrically unlock the door is called mechanical free egress. This is an important safety feature. In cases where the lock must be electrically unlocked on exit, the request-to-exit device also unlocks the door.
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