| 摘要 |
PURPOSE:To constitute a system with improved reliability and low cost by adding a system selecting function to a modulator and demodulator and connecting it to an information processing unit having plural systems of signal lines to eliminate the need for a communication line switching device. CONSTITUTION:The information processing unit 11 having signal lines A1-An of the system 1 and signal lines B1-Bn of the system 2 is connected to communication lines C1-Cn via a modulator and demodulator 10. When the device 1 uses the line C1 by using the system 1, the system selection switch of an operating section 13 is set to the selection of the system 1 to transmit a signal SE to a control section 14. When the control section 14 transmits a signal SF to a selection circuit 15, the circuit 15 selects the signal line A1 to transmit a signal SA1' from the unit 11 to a modulator and demodulator circuit 16 so as to transmit the output signal SA1 of the circuit 16 to the line C1. In setting the system selection switch of the operating section 13 to the selection of the system 2, the operating section 13 transmits the signal SE' to the control section 14. When the control section 14 transmits a signal SF' to the circuit 15, the circuit 15 selects the signal line B1 and transmits the signal SB1 from the device 11 to the circuit 16, and the output signal SB1' from the circuit 16 is transmitted to the line C1. |
