The term ‘Access Control’ generally refers to a system that can control, monitor and restrict the movement of people, assets or vehicles, in, out and around a building
Physical access control is a matter of who, where, and when. An access control system determines who is allowed to enter or exit, where they are allowed to exit or enter, and when they are allowed to enter or exit.
Historically this was partially accomplished through keys and locks. When a door is locked only someone with a key can enter through the door depending on how the lock is configured. Mechanical locks and keys do not allow restriction of the key holder to specific times or dates. Mechanical locks and keys do not provide records of the key used on any specific door and the keys can be easily copied or transferred to an unauthorized person. When a mechanical key is lost or the key holder is no longer authorized to use the protected area, the locks must be re-keyed.
Electronic access control uses computers 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.
The benefits of using an access control system include the prevention of loss or damage to capital assets and the reduced risk of personal injury to staff and visitors.Access control applications range from controlling a single entrance door to managing a large complex site.
Physical access control systems comprise three main components
The Physical Barrier
The physical barrier prevents the entry of unauthorised personnel and has a means of granting access electrically. These may be; a door fitted with an electric locking device, a turnstile, a parking gate or a lift. For doors, a magnetic door sensor may be added to monitor the door position, so that an alarm can be raises if the door is left open or opened illegally. Because there is no means of ensuring that only one person passes through a door when it is unlocked, strict rules must be in place to deter authorised users from allowing unauthorised people access through the door.
The Access Controller and Reader
The physical barrier is electronically controlled by an access controller combined with some form of reader to identify people by their 'credentials'. This may be a keypad, a card reader or a biometric reader. Together, the access controller and the reader provide the ability to identify an individual and authorise or deny entry to them.
Access controllers may either be ‘stand-alone’ or networked to a master PC-based (also known as ‘on-line’) access control system that manages the user database for all access points. The PC-based system software can update each controller with the details of each individual’s access rights.
PC-based access control systems can offer many additional facilities such as user location, attendance and usage monitoring, visitor management and automatically unlocking doors during emergencies and assigned periods.
The identity of an individual is determined by a ‘credential’, which may be a PIN code, an access card, key fob, or a unique human characteristic such as a fingerprint. In some cases, combinations of two or more of these credentials may be used to identify the person.