Access control is a system whereby staff members or residents can be authorised for access to a building or area of a building, whilst keeping unauthorised persons or visitors outside of the secured area.
The concept of Access Control isn’t a new thing - there has always been a need to protect people and assets in many different scenarios. Whether it is a single door with a lock and key or a moat and drawbridge around a castle, people have needed to limit access to sensitive areas for many years.
So the term 'access control' refers to the practice of restricting entrance to a property, a building, or a room to authorised persons. Physical access control can of course be achieved by a human - for example a guard, doorman, or receptionist, through mechanical means such as locks and keys, or via technological means such as Access Control Systems.
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 enter or exit, 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 unauthorised person. When a mechanical key is lost or the key holder is no longer authorised to use the protected area, the locks must be re-keyed.
Electronic Access Control solutions first appeared on the market in the 1960s, made to resolve the problem of lost keys, allowing the ability to add or restrict access for specific individuals, and to keep track of individuals’ comings and goings. Early access control solutions used basic keypads with Personal Identification Numbers (PINs) to gain access. Advances in technology allowed the use of magstripe swipe cards, and subsequently proximity cards, tokens and fobs which have now become ubiquitous.
Access Control Systems can, depending on type, perform many more tasks than simply allowing access. They can also maintain a history of user activity, can alert users and managers if a door is left open, can exclude users at certain times, and provide roll-call facilities. Some systems provide time and attendance features.
Access Control System operation
When a card or fob is presented to an access control reader, the reader sends the information contained within the card or fob, usually in the form of a number, to a control panel. The control panel compares this number to an access control list, grants or denies the presented request, and sends a transaction log to a database. When access is denied based on the access control list, the door remains locked. If there is a match between the number and the access control list, the control panel operates a relay that in turn unlocks the door. The control panel also ignores a door open signal to prevent an alarm. Often the reader provides the user some feedback, such as a flashing red LED for an access denied and a flashing green LED for an access granted.