Readers
A reader is typically installed on one or both sides of the entry point. There are a variety of readers available and vary in ease of use, security and price. The most common readers include:

• Proximity ("prox"): A credit size card is waved in front of the reader.
• Mag swipe: A magnetic strip on the card stores the users information. Credit cards are the most common example of mag swipe.
• Silicon key: A "key" is touched against the reader. The key fits on a key ring and is probably the most convenient to carry method.
• Key pad: A number is manually entered on a keypad. It provides easy access for many users but numbers are easily passed around.
• Smartcard: A computer chip inside the card stores information like account balances and other information. CS Technologies access control can also read a unique ID from some smartcards so they can be used as a credential.
• Biometrics: The use of physical attributes (finger print or retina image) provides the most secure method, but at a price.

Users and access levels
Each person will be assigned a "credential" (eg card, key or PIN) to identify them. They will be assigned to an access level with other users with the same requirements. The access level determines where a person can go (which doors) and when. For example, it is possible to have the door automatically unlock between 9AM and 5PM providing public access.

Other users could have access through the door between 6AM and 9PM. Finally some users could have access 24 hours a day.

Alarms
If the door is monitored (typically be a reed switch or similar device) then the system can tell if it is open or closed. If it is open it can determine if it is meant to be open and generate an alarm if necessary. The alarm could dial out to a security company, sound a local siren or report to the building manager.

Two types of alarm exist. A forced door alarm occurs when the door is opened without either a valid credential or the request to exit button being used. A door open too long occurs if the door is not shut within a configurable length of time. It is also possible to delay forced door alarms to occur if a door is opened for longer than a certain length of time.

Transactions
Everything that occurs with the controller is recorded. This includes the use of credentials, the forced entry in doors, as well as automatic functions. This then allows comprehensive reports to be run at a later date.

Settings
The following times are all programmable:

• Release time: The length of time the door is unlocked after a valid credential
• Public access time zone: When the door will automatically lock and unlock
• Door open too long time: How long the door can be held open after a valid credential before an alarm occurs
• Forced door delay: How long the door can be held open without a valid credential
• Reporting time zones: When request to exit and alarm transactions are to be recorded.

Antipassback
If an area has a reader to enter and a reader to exit, it is possible to stop a credential from being used twice in one direction. The credential must be used to go the other direction before it is used again. For example, in a carpark the credential must be used to leave a car park before it can be used to enter again. This stops a credential from being passed around letting multiple cars into the carpark.

Car park counter
It is now common for departments or tenants to be allocated a set number of places. These places are not individually assigned and could be required by many people. Access levels can be assigned to car park groups. Each group will then be allocated a number of spaces. Each time a user enters the current count will increase. The same credential could even be reused to let more people in. Once the limit is reached, however, no more users from that group will be able to enter.

Applications
Despite its name, the door controller has been used to control: -

• Roller shutters
• Boom gates
• Air conditioning
• Lights
• Pumps (in a truck wash!)
• Alarm systems
• PC access
• Fork lifts
• Machinery

As well as doors:

• Sliding doors
• Glass doors
• Wooden doors
• Metal doors
• Disabled doors