How an access control system works and what it is made of

The five parts of any system

1. Credential. What identifies the person: card, fob, phone, PIN or a biometric trait.
2. Reader. The device by the door that reads the credential and passes it to the controller.
3. Controller. The "brain": it stores who may use each door and when, takes the decision and releases the lock. It belongs on the secure side, not on the outside of the door.
4. Locking device. Electric strike, maglock, motorised lock, turnstile or barrier — whatever physically stops or allows passage.
5. Software. Where people are enrolled, permissions assigned and logs reviewed.

Around them sit less visible but equally important parts: a battery-backed power supply, the exit button, a door contact that reports a door left open, and the cabling.

What happens in one second

1. You hold your card to the reader.
2. The reader sends its identifier to the controller.
3. The controller checks three things: the credential exists and is active, it is allowed on that door, and it is within its schedule.
4. If everything matches, it releases the lock for a few seconds and logs the event. If not, it denies access and logs that too.

The decision is taken in the controller, not in the server or the cloud. That is why a well-designed system keeps working when the network goes down.

Standalone and networked systems

• Standalone. A keypad or reader that decides by itself and opens one door. Cheap and enough for a store room or small shop, but with no central log: to remove someone you have to go to the door.
• Networked. Several doors managed from one piece of software, with schedules, groups, event logs and instant revocation. It makes sense from two or three doors up, or wherever staff turnover is high.

Common mistakes

• Putting the controller outside, or using an all-in-one reader on a street door: whoever removes the reader can bridge the lock.
• Forgetting the way out. Decide how people leave (button, free handle, panic bar) before choosing a lock. See access control and evacuation.
• No battery backup. Without it, a power cut leaves doors open or locked depending on the type of electric lock.
• Choosing the credential last. It determines the reader, the cost per user and the security: see which credential to choose.

Where to start

List your doors, your groups of people and your schedules. With that, any installer can give you a comparable proposal. If you would like us to go through it with you, this is our business access control service.