| 摘要 |
PURPOSE:To improve the transmission efficiency and to prevent generation of plural master devices by allowing a master deive to form a timing in itself among plural transceivers connected to a loop form data transmission line so as to transmit a data for the own device's share and polling request to other devices. CONSTITUTION:A polling request is outputted from a device No.1 at a normal state (Fig. A), each device receives it and outputs a device name of the own device and a data to a tansmission line. Since the polling request for the own device does not exist, the transmissio efficiency is inproved. If plura sets are operated in error as master devices (Fig. B), when the master device receives the polling request, a flag as the master device is cleared and the own device is brought into a slave device. Thus, even if the system is disturbed tentatively, the system is restored automatically. |
