| 摘要 |
PURPOSE:To obtain a communication-circuit switching device which does not require a switching control line, etc., by receiving a control signal on a modem interface, and knowing a communication request and automatically forming a communication channel. CONSTITUTION:Communication processing parts 1-1 and 1-2 are used as an in- use and a stand-by system, and a modem 3 is in a communication state. The modem interface 5-3a of a modem 3 is changed from the interface 5-1a of the processing part 1-1 as the in-use system over to the interface 5-2a of the processing part 1-2 as the stand-by system. When a communication-circuit switching device 20 detects a communication request from the processing part 1-2 at the rise of a signal RS2, the interfaces 5-2a and 5-3a are connected mutually, and interfaces 5-1a and 5-3a are disconnected from each other. When a communication path for the stand-by system is connected, the communication request signal RS2 from the processing part 1-2 is supplied to the input of the modem 3, which is started by the signal RS to return a transmission ready signal CS3 to the processing part 1-2 through the device 20. |
