A modular bus system for reporting the status of a plurality of geographically distributed data points. The data points may be independently located or grouped with the status of each being monitored by a processor which is coupled to the data points via a bus multiplexer, a plurality of buses and a...http://www.google.es/patents/US4360912?utm_source=gb-gplus-sharePatente US4360912 - Distributed status reporting system
