The Complete Handbook of Key Card Entry Systems

Chapter 1: Understanding Key Card Entry Systems

A key card entry system is a mechanical and electronic assembly that controls physical access by reading coded information from a portable card, then triggering or denying the opening of a door. In a typical installation, an employee or resident carries a card. When they approach a reader mounted near a door or gate, the reader detects the card, decodes its information, verifies it against a database or access list, and sends a signal to an electric lock or strike plate. The door opens. If the card is invalid, inactive, or assigned to a person with no access to that door, the reader does nothing and the door stays locked. This simple sequence—read, verify, actuate—has become the standard mechanism for controlling access in offices, hotels, hospitals, apartment buildings, laboratories, data centers, and secure facilities.

The reason key card systems have displaced traditional mechanical locks and keys in most commercial settings is not glamour or technology for its own sake. It is that key card systems solve specific, expensive problems that mechanical locks cannot. When someone leaves a company or loses a key, you must rekey the entire lock—a costly, time-consuming operation. With a card system, you deactivate one card in software. When you need an audit trail showing who entered which door at what time, a mechanical lock gives you nothing; a card system logs every transaction. When you need to grant temporary access to a contractor for one week in one zone,