Redundancy modem

摘要

A communication system providing for the duplication of data and information transmission between programmable controllers is disclosed. A modem is provided for each programmable controller and each processor within a programmable controller in the system, and the modems are interconnected by pairs of coaxial cables. Each transmission from a programmable controller or processor within a programmable controller is simultaneously transmitted via its associated modem over both cables to all of the other programmable controllers and processors within programmable controllers in the system. The receiving modems select the data or information from one of the cables, based on the integrity of the data being received, and transmit same to its associated programmable controller or processor within a programmable controller.