| 摘要 |
<p>PURPOSE:To power off one side of dual-board constitution at all times and to reduce the power consumption by providing power switches controlled mutually by the boards in the dual-board constitution. CONSTITUTION:Power source input switches 5 and 5A are provided between a power source 10 from a power supply board 4, and the boards 1 and 2. The power switches 5 and 5A are controlled with the detection outputs of signal detecting circuits 8A and 8 respectively. In an initial state, a signal is outputted to a signal line 9, the stand-by side board 2 is not supplied with electric power, and a signal inputted to a selection board 3 is the output signal of the board 1. If a fault occurs to the in-use side board 1, the signal detecting circuit 8 connected to the output of an output buffer 7 detects the fault and turns on the power switch 5A of the stand-by side board 2 through a control line 11. Consequently, the board 2 operates and the signal detecting circuit 8 detects the operation of the signal and turns off the power switch 5 of the board 1 thorough a control line A.</p> |
