Access Control


What is it?
Access control is the restriction of access to a place or area. Electronic access control systems are used to interface with locking mechanisms on doors, gates, or any entry way to prevent unauthorized access.

How does it work?
You may have an access control card to get into your office building or gym. Before you get an access card, someone enrolls you as a cardholder into the system and defines what doors you can open. Usually, your credentials will even drill down to a particular time range and only allow you to open doors during certain hours.

When you swipe your card at the card reader, it reads the information on the card and carries it back to the system controller. The controller compares the information that it receives to how it has been programmed. If you’ve been programmed with permission to enter that particular door, the controller will send an unlock command to the electrified door hardware. The door opens, and you’re in business.

Devices & Functions

Server & Software
All access control systems have a server of some kind. The server provides a software interface to manage people, time schedules, and run activity reports. Sometimes the server can be embedded in the controller and accessible through a web browser as a web page. However, you will typically have a dedicated computer running the software for your access control system.

The controller or panel is the main circuit board and communication hub of an access control system. All of the door Equipment (Card Reader, REX, Door Contact) wires back to the controller. It is usually mounted on the wall in an electrical room or IT room but can be mounted in a rack with other communication equipment.

Card Reader
The card reader is the device that goes on the wall next to the door. There are many types and varieties.

Request-to-Exit (REX)
The motion detector in an access control system is called a Request-to-Exit, REX for short. When you are exiting through an access-controlled door from the side that does not have the card reader (secured side), the REX will detect that you are about to open the door from the inside. This lets the controller know that the door is not being forced open from the non-secured side.

Door Contact
The door contact indicates door position, open or closed, to the controller. It can be installed anywhere in the door frame, and a small magnet is placed opposite the contact on the door.

Electrified Door Hardware
This is the locking mechanism on the door or in the door frame. When a cardholder presents a card to a reader and is granted access a signal is sent to the power supply that drives the electrified door hardware. The door is momentarily unlocked.