Yokogawa Electric Corporation

Hideo Matsukawa

Shunsuke Hayashi

Toyoaki Yokoi

Hideyuki Sakamoto

Toshiaki Shirai

Chuji Akiyama

Hitoshi Yasui

Yasuhiko Shioe

Makio Ishikawa

A communication control system and method comprising, in one embodiment, a plurality of strobe signals are generated at different timings in a transmission circuit and a plurality of latch circuits equal to the number of strobe signals are provided in a receiver circuit so that data is retained in each latch circuit using the strobe signals one at a time.

Communication system and communication control method

A communication control system and method comprising, in one embodiment, a master station connected to a slave station using two redundant buses, wherein command frames having the same content are sent out to the buses and the communication process is changed depending on whether or not the contents of the command frames, when received by the receiving station, are identical.

A communication control system and method comprising, in one embodiment, a master station connected to a slave station using two redundant buses, wherein command frames having the same content are sent out to the buses and the communication process is changed depending on whether or not the contents of the command frames, when received by the a receiving station, are identical. In another embodiment, a plurality of units are connected to each bus in a multi-drop configuration, and a line length of each bus is defined so that reflected signals from other units reach a receiving unit on each bus after the transition period of a received signal at that receiving unit ends. In still another embodiment, a unit is connected to each bus and the unit is provided with a driver IC, wherein transmission data is first encoded into bit signals having a fixed number of bits, then the signals are supplied to the driver IC. In a further embodiment, a plurality of strobe signals are generated at different timings in a transmission circuit and a plurality of latch circuits equal to the number of strobe signals are provided in a receiver circuit so that data is retained in each latch circuit using the strobe signals one at a time. In a still further embodiment, an arbitration procedure is carried out using an arbitration bus when a bus master desires to use a data bus immediately after using the data bus, wherein it is determined whether arbitration has been carried out using the arbitration bus, and if none has been carried out, the arbitration procedure is omitted and the bus master is allowed to aquire the right to again use the data bus.

A distributed control system comprising a control station and a remote input/output device interconnected by a bus, wherein the system is provided with a continuation transmission service which first transmits an urgent output only and then performs cyclic scan transmission; an initialization start transmission service which first performs cyclic scan transmission for input only; an interruption duration measuring feature which measures the period of transmission interruption; and a control feature which activates the continuation transmission service when the result of the measurement is shorter than a predetermined period of time, and which activates the initialization start transmission service when the result of the measurement is longer than the predetermined period of time. Thus, for example, after a power supply failure, the system can rapidly recover and shift to normal process controlling operation without the delays normally experienced by prior control systems.

Growing community of inventors

Tokyo, Japan

Hideo Matsukawa