IMPROVED CARD READER FOR SECURITY SYSTEM

摘要

This application relates to the field of door access security systems and, particularly, to the field of card readers for door access security systems. A problem arises when communication between a remote card reader and the central controller is lost. If all access is denied during such times, peoples lives may be endangered. If open access to anyone is granted, security may be breached with no record of who was granted access during the down or degraded mode period. There is disclosed herein an improved card reader (22) for a security system utilizing a central controller (20) and a plurality of card readers for controlling traffic through critical doors in a facility. During normal operation, the card readers read card data and send it to the central controller. The central controller makes the decision whether to grant or deny access based upon a comparison of the card data and data kept in memory regarding persons who are authorized access to certain areas. The central controller then sends a "Go" or "No Go" message, i.e., whether or not to grant access, to the reader after the access decision is made. The improved card reader can also sense when communications with the central controller are lost and grant or deny access without consulting the controller, based upon data read from the card by comparing the card data to data stored in a degraded mode buffer (89) in the reader, indicating which persons are authorized access during degraded mode times when communication with the central controller is not possible. The improved reader includes means (89) for storing the authorized identification code data for persons who will be allowed access during times when communications between the card reader and the central controller are not working.