PURPOSE:To block operating information from other system for a required time and to operate a system selecting control circuit with a bit by extracting the control bit to start a load drive circuit from the load drive information of a system requesting drive. CONSTITUTION:Control circuits 1, 2 and load drive circuits 3, 4 are connected fixedly by one to one and which system is used is discriminated by monitoring a drive signal from the control circuits 1, 2 to the load drive circuits 3, 4. Then, a signal significant bit of the drive signal from the control circuits 1, 2 is inputted as a data to information storage registers 12, 13 of a system selecting control circuit 5, and 0 or 1 is set to the registers 12, 13 in response to the transmission system. The system 0/1 is decided depending on the content of the register and the command of selection is transmitted to a selecting circuit 11. In this case, the input of the register of the other system is blocked and released at the transmission of the end signal. That is, the system is selected automatically by the drive signal from the control section so as to form a connecting route between a load drive circuit and a load.
展开▼
