Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Engineering Company, Limited

Noriyuki Hattori

Noboru Takahashi

Masanori Yamazi

Minoru Muto

A transmission system comprising a plurality of stations, each having transmission and receiving circuits, that are connected in a ring configuration and use a HDLC-type protocol for transmission. The fault of a transmission circuit in a station can be detected in an idle state time by transmitting a fixed bit pattern during an idle state of transmission. Each station has a fixed bit pattern generator for outputting a fixed bit pattern during an idle time. Each station also has fault detection means which detects a fault when it receives a signal other than transmission data and the fixed bit pattern. Since the state of a line can always be monitored, a fault of the line state can be rapidly identified. Since transmission data is not encoded, the data transmission can be conducted at a high speed.

Communication system and method of detecting transmission faults therein

A transmission system formed by a master station and a plurality of satellite stations which are connected by a transmission line into a loop, the data and command signals from the master station being passed sequentially from station to station around the loop. A failure in a satellite station that prevents further loop transmission is detected by watchdog timers in one or more successive stations. As a result, the stations detecting the failure switch themselves into a bus-mode of operation, the master station switches itself and the remaining stations into the bus-mode of operation. The switching back to the loop-mode of operation can be performed under control of the master station automatically, upon detection that the failure has been corrected. The switching also can be performed under external command.

Growing community of inventors

Aichi, Japan

Noriyuki Hattori