PURPOSE: To simplify the constitution of a control system and to assure the monitor and control for the load connected to a slave device, by providing a latch to store the address of a slave device, the state of load and a synchronizing signal and a retransmission request circuit which switches the synchronizing signal and retransmits a confirming signal to a master device.
CONSTITUTION: When a confirming signal is transmitted to a slave device from a master device, a control signal is transmitted synchronously with a synchronizing signal. Then the address and the synchronizing signal of the slave device to which a reply is sent back are stored in a latch 19. Then a synchronizing signal produced from an output C of a retransmission request circuit 34 is applied to a switch circuit 33, and then a retransmission request signal synchronized with the synchronizing signal is applied to a transmission data producing part 17. Then the address, the reply data and the synchronizing signal of the slave device having a reply are stored again to the latch 19. Thus it is possible to monitor the loads connected to all slave devices which are connected to a power line 2.
FUKAGAWA HITOSHI
SUZUKI YOSHIHARU
KOMODA YOSHIYUKI
