| 摘要 |
PURPOSE:To prevent a device from disabling communication over the whole circuit by a fault of one station and to give the degree of freedom to an increase and decrease by in the number of stations obtaining a synchronizing control signal from a commercial power source waveform and supplying said synchronizing control signal to a communication controlling means, and performing decentralized control at respective stations. CONSTITUTION:A detecting circuit 6 of a power source synchronizing signal generates a synchronizing signal (b) synchronizing with a power source frequency from two kinds of signal superposed on a commercial power source line 1. A communication control circuit 5 outputs an information signal on the basis of the synchronizing signal (b) and the signal is outputted to the commercial power source line 1 through an amplifying circuit 4. A data packet is outputted at time t1 in a figure. The information signal on the commercial power source line 1, on the other hand, is amplified by an amplifying circuit 3 and then applied to a control circuit 6 again as shown in a figure (d). The amplifying circuit 3 detects the transmit signal of another station as well. The other station receiving the signal from the main device at time t1 detects signal absence on the power source line 1 and then sends out an ACK packet for the confirmation of the reception at time t3. The data packet sending station handles the ACK packet. |
