Making Sense of Access Control

The need to control access into and out of buildings is fundamental to maintaining effective security. Not only is this important from the perspective of asset protection, but also for the safety of those who live, work at and visit these locations.

The immediate objective of an access control system is to deny entry to unauthorized individuals. Included in this mission is the need to allow authorized individuals to enter at will without creating a traffic jam at key portals.

An effective access control system creates an audit trail of authorized actions and events as they occur. User data should include time and date of each entry as well as exit data when egress readers are employed on the inside of the building. The audit trail feature enables building management and/or security personnel to quickly determine culpability when a crime has taken place. This data is especially valuable to law enforcement when there’s no sign of breaking and entering.

Stand-alone vs. multiple-portal

There are two basic kinds of electronic access control systems on the market: stand-alone and multiple-portal. A portal is any opening that we seek to control. Examples include a common door and an overhead door.

A stand-alone system offers the advantage of economy while incurring the limitations associated with single-door operation. Because this type of system operates on a local level, there are no cables to install between the portal and a central control system or a host computer.

A facility equipped with a stand-alone access control system today might require the integrated, centralized approach later. The latter requires the use of network technology, often forming a proprietary local area network (LAN) that often runs parallel to the one already installed for office use.

One way to accommodate the possibility of expansion later is to buy dual-use stand-alone units now. Cost still is often a motivating factor in the use of dual-purpose or convertible access control equipment at the door, but when the network approach is needed, the same reader/controllers will communicate with a centralized host.

There are advantages to using the network approach right out of the gate. A fully functional multiple-portal system has the added benefit of scalability. This type of system allows security technicians to build what is required today while allowing for expansion later. These systems can accommodate hundreds of doors.

The greatest incentive associated with networking access control is programming time. In a stand-alone environment, management often will use a portable programmer that enables them to enter the operating criteria, but in this case they are forced to do it door-by-door.

In an integrated network environment, the same programming effort can be accomplished in a fraction of the time with the press of a single key on a centralized PC. Here, the data is entered just once, and the network carries it to each door reader/controller unit simultaneously.

Another benefit of a fully networked system is that a detailed audit trail of all events can be stored and uploaded to the central host. In this case, access to the data can be achieved at a single work terminal where it can be saved and printed. Stand-alone reader/controllers require someone to carry a hand-held printer door to door, printing activity data on a small roll of thermal paper.

Determining identity

Personal identity can be determined at the portal using one or more of several technologies. In brief, these include the following:

• Keypads

• Card readers

• Biometric readers

Probably the oldest method of establishing identity is through the use of a keypad. Users are issued a unique personal identification number (PIN). They enter the PIN as they walk into a building, and the data is analyzed either inside the keypad or at the host. When authorization is granted, the system transmits the go-ahead, and the access controller automatically unlocks the door.

A card reader, on the other hand, is a device that “reads” a unique ID number contained within or on a card or keyfob. A keyfob uses radio frequency identification (RFID) technology to store and transmit data to a reader. The access card, which also contains user data, is inserted or swiped through a card reader positioned at one or more doors.

Biometric access readers also are designed to establish a user’s identity using unique ID criteria. In this case, instead of a PIN or unique ID number within a card, a unique physical or behavioral trait that belongs to the user is employed. This biological information can be in the form of a finger, hand, voice or eye print. An example of a common behavioral trait is one’s signature.

Access control strategies are complicated, but these projects are a perfect fit for a qualified installer.

COLOMBO is a 35-year veteran in the security and life safety markets. He is director with and a nationally recognized trade journalist in East Canton, Ohio. Reach him at

About the Author

Allan B. Colombo

Freelance Writer
Allan Colombo is a 35-year veteran in the security and life safety markets. He is director with and a nationally recognized trade journalist in East Canton, Ohio. Reach him at

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