| 摘要 |
PURPOSE:To easily execute response and recognition to a master station even at the time of status change start of plural slave stations by providing each slave station with a random number generator for controlling retry timing at the time of collision of status changing start and forming one bit for deciding the existence of status change in a transmission format. CONSTITUTION:The master station 7 is connected to plural slave stations through a transmission line 6 of one route. When status change start is generated in plural slave stations 1l-1-1l-n, the slave stations 1l-1-1l-n detect carrier signals on the transmission line based upon other stations through a MODEM 5. Then, a delay time is calculated by the random number generator 9 and the status change start is retransmitted to the master station 7. Consequently, the slave stations whose status change start collides with each other can execute status change start without collision at the time of retransmitting the status change data. In addition, one bit for deciding the existence of status chage is added to the transmission format. Thus, response and recognition to the master station can be easily attained.
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