| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication unit that prevents data from being duplicated on a communication line by taking synchronization with other option unit. SOLUTION: When a reception buffer of an option unit receives data (S401), a CPU reads data of the reception buffer to a RAM (S402). When the read data are a header, the header is set to a transmission buffer (step S404) and reception of succeeding data is awaited (S405). When receiving succeeding data, whether or not a unit number (ID) assigned at initial communication after application of power has a value '1' is confirmed (S407). When the unit number is the value 1, status data are set to a transmission buffer (S408), and when the number is not the value 1, the received data are set as they are to the transmission buffer (S409).
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