This universal bus has many applications. With a PC as a master, information can be exchanged with up to 64 slave terminals. Because each terminal contains eight selectable inputs and outputs as well as an LCD, this home network is not only suitable for use in the home, but it would also be perfect as a combined alarm/communication system for schools and small firms.Before we delve into the technical details, we will first give a brief description of the system.The backbone of the system is a complete serial bus that uses its own protocol. Data is sent to and received from a maximum of 64 terminals over long distances using an RS485 interface.The hardware of the system consists of a simple RS232 to RS485 converter and a microprocessor driven terminal. Of the latter you will obviously need to build as many as are required. The software consists of a program for the PC and one for the ‘terminal processor’.