| 摘要 |
PURPOSE:To eliminate erroneous judgement in case of an input break state by applying an inhibition signal to the input break detecting circuit of a multiplexing device switched to a stand-by side through a switching device, and inhibiting the output of an input break warning signal. CONSTITUTION:A switching control circuit SWC controls switching devices SWa and SWb; which of multiplexing devices MPX1 and MPX2 is on an in-use side is discriminated easily and an inhibition signal is applied to the input break detecting circuit of the multiplexing device on the stand-by side. For example, when the multiplexing device MPX2 is on the stand-by side, the inhibition signal is applied to the input break detecting circuit DET2, which never outputs the input break warning signal to a warning board ALM even in an input break state. When the multiplexing device MPX2 is switched to the in-use state, the inhibition signal is applied to the input break detecting circuit DET1 of the multiplexing device MPX1, so only the multiplexing device in use detects an input break and never output an unnecessary warning signal. |
