| 摘要 |
PURPOSE: A circuit for changing a communication subject for a multipurpose communication port is provided to efficiently perform multifunctional communication using a circuit for changing a communication line according to an operation mode. CONSTITUTION: In a transmission path changing unit(100), a transistor(T2) is turned on/off according to a mode signal inputted to its base through a resistor(R4). If the transistor(T2) is turned on, a signal inputted to its emitter(T2E) is outputted to its collector(T2C). If the transistor(T2) is turned off, the collector(T2C) and the emitter(T2E) are turned off. In a receipt path changing unit(200), a transistor(T1) is turned on/off according to a mode signal inputted to its base through a resistor(R3). If the transistor(T1) is turned on, a signal inputted to its emitter(T1E) is outputted to its collector(T1C). If the transistor(T1) is turned off, the collector(T1C) and emitter(T1E) are turned off. A signal blocking unit(300) blocks a TCU(Transfer Control Unit) signal so that a signal inputted from the TCU is not a microcomputer(10) when operating the receipt path changing unit(200).
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