A real-time reconfigurable entrance control system

A real-time reconfigurable entrance control system is presented in this paper. The system is designed and implemented with considering compatibility with the existing systems, reliability, expandability, and maintenance. The presented system consists of a host which manages a central database, terminals which control entrances, and terminal controllers which connect the host with terminals. To utilize the existing popular network, Ethernet is used for the network between the host and terminal controllers, while LONNET is used to connect terminal controllers and terminals. The software in each terminal controller and terminal is divided into two parts. The kernel part which is unchangeable for the normal cases is responsible for low level communication and house keeping. The application part controls peripherals. It can be replaced with a new one with aid of the kernel during initialization process or even on-line operation. With this approach, an application program can be modified without stopping the system. Another advantage is that installation and maintenance become very easy, saving the related cost