| 摘要 |
PURPOSE:To detect the existence of a mounting connection even by a system having no input signal, by detecting the existence of the connection by a controlling circuit without providing an independent exclusive input line for detecting the mounting existence. CONSTITUTION:A controlling circuit 1 controls a circuit to be controlled 2 which is attachable and detachable, and said circuit 1 and each circuit to be controlled 2 are connected by one control line 3, respectively. In this state, the n-th control signal Sn is supplied to an input of an output gate 4-n and an output of an input gate 5-n, also inputted to an input gate 7-n of a circuit to be controlled 2-n through said control line 3-n, and the circuit to be controlled 2-n is controlled. In this case, a +5V power source is connected through a resistance R to an input end of the circuit to be controlled 2, and a discriminating signal as to whether the circuit 2 is mounted and connected to the controlling circuit 1 or not is generated. In this way, the mounting existence of the circuit to be controlled 2 can be detected by a difference of a signal level of an output side of an input gate 5 even in case when only the control line 3 is connected. |
