Access Control Overview: Access Control refers to the practice of restricting entrance to a property, building or room to authorized people. This can be accomplished by a person, such as a receptionist or guard, or by mechanical means such as locks and keys. More recently, Access Control has come to be accomplished by technological means using (primarily) card access systems.

The most common type of Access Control system uses access control cards and card readers. These systems use readable cards that allow cardholders to unlock doors by presenting their card to a reading device, offering many more advantages than simple mechanical push button keyless locks. In its simplest form, a card will either unlock the door – or not. In more complex systems, a particular card may only allow entry through some doors and not through others, or it may allow entry at particular times and not at others. Necessary information about who has what card and what access each one has, are stored in the controller(s). The readers at each access controlled door relay the particular card ID to the controller(s) which validates the card’s associated access permissions and either sends a signal to the door to unlock – or not.

Controllers may be configured and card users enrolled into the system by using a reader and keypad or remote control device. Usually if it is a simple single door system with few users, configuration and enrollment is performed using a reader and keypad or remote control device. Multi-door, more sophisticated systems use the supplied software program. Information about card holders and permissions is uploaded to the access controllers from the software. Card users can be added and/or removed and access schedules and permissions changed very easily using the software. The PC running the software can be attached to the controllers permanently or as needed. The software can be used to monitor access activity both historically and real-time. A log is generated of which card was presented to which reader, by time, and whether the respective door was opened therefore creating a history of who went through which door and when.

Controllers come in single door or multi-door versions, depending on the manufacturer. Many single and two door controllers can be connected together in a network, so that all can be configured and updated at the same time from a connected PC. Using controllers that are networkable, such a system can be easily expanded to accommodate more doors - even in other buildings.

Card readers can use a “Swipe” card (magnetic stripe) but generally today use “Proximity” cards which use RFID (Radio Frequency Identification)that only need to be held near to the reader for the card’s ID to be read. This type of card has the advantage of never wearing out and being very difficult to duplicate, However, proximity cards can be misplaced, stolen or “lent” allowing unauthorized access. Because of this, in very secure areas, additional methods of entering unique user information are used. This varies from a simple PIN on a numeric keypad to biometric devices such as fingerprint readers or even retinal or facial scanners. In most cases, these are used in conjunction with a card reader.

Doors are locked and unlocked using an Electric Strike or Magnetic Lock. When a card with the appropriate permissions is presented to a reader, the controller sends a signal to the locking device unlocking the door. Electric Strikes and Magnetic Locks can be either Fail Safe (powered when locked) or Fail Secure (Not powered when locked). In general, buildings without a Fire Alarm system use Fail Safe locks that open during a power failure. In buildings where a Fire Alarm system is installed, Fail Secure electric locks can be used. The Fail Secure locks must be connected to the Fire Alarm system so that in the event of a fire, all the doors will be unlocked by the Fire Alarm system. Magnetic Locks are always Fail Secure, while Electric Strikes can be either Fail Secure or Fail Safe.