How Access Control Systems Work

A secure business relies on more than just good security cameras and well-placed burglar alarms. You need a solid access control system to help you coordinate the flow of traffic through your building, report potential security breaches, and log traffic for later review.

Whether you’re using keycards or biometric scanners, you face the basic challenges inherent to any dynamic, context-based system, and you need to know your priorities when it comes to your security settings. Access control systems can be tricky to understand, but knowing how they work is the first step to securing your business. If you aren’t sure how access control systems work or just want a little refresher course, this guide should help you figure it out.

Understanding the Basics

While the practical application of these systems is complicated, the basic concept is actually pretty straightforward – you submit your credentials to a scanner that sends the data to a control panel, which determines whether your credentials match those in the database. If they do, the panel sends a signal to unlock the door; if not, the panel simply keeps the door locked.


Your access control system starts with the server. Whether you use an on-site server or rent space on the cloud, the server stores and manages the list of approved credentials issued to individuals. This whitelist can be updated as needed to reflect changes to your security. The server also stores all entry and exit data, allowing you to retrieve the information for later use.

On-site servers are generally housed with a dedicated terminal and cannot be managed from anywhere else. While this is highly secure, it’s also more expensive to install and maintain. A dedicated IT team is generally needed to update the system and make sure everything is running smoothly, because you certainly don’t want a comparatively simple system update making your access control system unusable.

Cloud-based access control systems like Brivo OnAir skip the on-site server and host the whitelist for you, allowing you to access and update your database from anywhere you’ve got a wireless or cellular signal. Since you’re using their server, you don’t have to worry about managing an IT team either, but you also won’t have the specific level of control over your database you would if you owned your own server.


Credentials can be virtually anything that stores data – PIN codes, proximity or magnetic strip keycards, key fobs, fingerprints, even smartphones. Regardless of the format, they should always be unique to the individual. Each credential has a unique ID number assigned to it that will be read by the scanner described below.

For the more security-conscious, it’s best to require more than one of the above credentials to open the door. Two-factor authentication readers are quite common, often combining a fingerprint scanner or card reader with a PIN pad for additional security. The credentials must match not only the whitelist, but also each other – using two authenticators from two different people will not open the door.


The type of scanner you use depends on the kind of credentials you choose. They might be PIN readers, mag strip readers, RFID scanners for prox cards, fingerprint scanners, or cellular receivers for a smartphone signal. All readers take the scanned credentials and convert their data into Wiegand numbers, a universal protocol readable by all door controllers.

Door Controller

This central hub is the heart of your access control system. All your door readers are connected directly to the door controller, which compares the Wiegand ID to the whitelist on the server. If the credentials match, the controller signals the door to open or unlock. Because all door controllers read the Wiegand protocol, any door controller can communicate with any reader (barring brand-name incompatibilities).

Door Locks

The locks you have hooked up to your door controller largely depends on what kind of doors you have and your specific security needs. The best locks for access control systems are electromagnetic plates mounted at the top of the door – they’re incredibly strong and reliable. Automatic doors may also be wired into your door controller – instead of just unlocking, they’ll unlock open for approved credentials.

electromagnetic door lock

Other types of conventional door locks include the everyday cylinder lock and the older mortise lock. Cylinder locks are the standard doorknob-and-deadbolt combination used on nearly every house in the United States. Mortise locks look somewhat similar on the outside, but the mechanism is much larger and set into a hollow in the door instead of through a simple hole. Mortise locks are easier to fit an access control system to and more secure, but electronic locks can be added to cylinder locks as well.

Get Safe and Sound

Now that you understand how access control systems work, you’ll need to determine how you want yours set up. Like most security systems, access control is best installed by professionals, so if you’re interested in getting an access control system or a little more information, give Safe and Sound Security a call. We’ve been California’s best local access control system installer for nearly 10 years, and we’re eager to share our expertise and experience with you.


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