US Patent 7487266 Communication system and method, and distributed control system and method

A communication system performs bidirectional communication through a same communication path every communication cycle period between a master station and a slave station. From the start of the communication cycle period until an interval period shorter than the communication cycle period elapses, the master station transmits master data represented at a first ratio of first pulse width to the communication cycle period to the slave station. In a remaining period after the interval period in the communication cycle period, the slave station transmits slave data represented at a second ratio of second pulse width to the interval period to the master station.