| 摘要 |
PURPOSE:To surely identify transmission signals and to increase the transmission speed, by superimposing one word with maximum bits on a transmission signal near both the sides including the zero phase point of a power supply. CONSTITUTION:An operation panel 2 is connected to a power supply side of a power line 1 and a plurality of control terminals connecting a load 4 and a monitor terminal device 5 connecting a monitor device 6 are connected at load side. The operation panel and each terminal unit have input/output interfaces 21, 22, microcomputer 23, zero cross circuit 27, clock circuit 25, and counter 28, and a transmission signal is superimposed via the input and output interface on a power supply line 1. Three sections T1-T3 are set near the zero phase of power supply waveform for the transmission signal with the circuit 27 and the counter 28, and the signal is transmitted in synchronizing with the sections. A start word is superimposed on the sections T1, T2, T3 [Fig (a)] and each word for address, control and return is superimposed over several cycles by one-bit on the sections T1, T3 [Fig. (b)], and a request word from a terminal 5 is superimposed at the section T2 [Fig. (c)]. |
