Importance

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Abstract

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.

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First Claim