| 摘要 |
PURPOSE:To shorten the time of one cycle by polling a slave station in operating at a fixed interval within one cycle and polling unoperated slave stations in the residual time at the polling of plural slave stations by a master station. CONSTITUTION:The master station 10 is connected to n slave stations through a line 11. Receiving a polling indication from an opposite station selecting part 14 for polling, a polling execution part 13 in the master station 10 starts a timer and poles the indicated slave station (initially, the order of addresses). When the polled slave station is being operated, the slave station is received through a communication control part 12 and no response is generated from unoperated slave stations responding to a polling response execution part 17. The response is informed to the opposite slave station selecting part 14 and a network control and monitoring part 15. The opposite station selecting part 14 polls the slave station in operating at a fixed interval, and if residual time exists, poles unoperated stations. When the time is lacing, a timer is restarted. Consequently, polling can be efficiently attained.
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