| 摘要 |
PURPOSE:To reduce a data transmission/reception time between communication stations by providing an internal memory storing station connection presence information and station normality information of all communication stations and checking the said memory in transferring the right of communication master station. CONSTITUTION:A frame 12 is a frame where a communication master station right transfer command to the end of a data transmission/reception frame. The connection presence information and the normality information as to all communication stations are stored to a station information memory 13 provided to each communication station. A communication station A1 being about to transmit the frame 12 checkes the memory 13 in advance, and for example, when a communication station B2 is not connected or faulty, a communication station C (not shown) having the priority next to that of the communication station B2 is connected and in normal state, the communication station C is designated by using a destination address in the said command so as to elimi nate a case requiring retransmission of the command of communication master station right transfer.
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