| 摘要 |
PROBLEM TO BE SOLVED: To relieve an arithmetic load on a CPU without losing a function of detection of a broken communication transmission line. SOLUTION: In this multiplex communication system, each of slave stations 200a, 200b stores data newly sent from a master station 100 into a reception register 502, and stores data given from a CPU 201 of its own into a transmission register 506. A reception data coincidence discrimination circuit 532 discriminates whether or not the data newly received this time are coincident with the data received precedingly and outputs a signal 516 to stop read/write processing of the reception register and the transmission register to the CPU 201 of its own. Thus, the load of repeating read processing of the same data to the reception register and of repeating write processing of the same data to the transmission register on the CPU of the slave stations 200a, 200b is relieved, the necessity of provision of a CPU operated at high speed is eliminated and the system cost can be reduced.
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