| 摘要 |
PURPOSE:To assure the back-up to a stand-by system from a working system, by performing occasionally a repetitive check to both working and stand-by systems. CONSTITUTION:A back-up controller 4 contains a check circuit 5 in addition to a monitor switch circuit 6. The circuit 5 delivers test signals occasionally, e.g. in a fixed cycle via buses 3a and 3b to check the normal functioning of a working system CPU1a, a stand-by system CPU1b, and memories 2a and 2b respectively. If a fault is detected, an error signal is delivered to a display circuit 8 to show the generation of the error. Thus a check is occasionally given also to the normal functioning of the stand-by system. Thus, a fault of the stand-by system can be excluded previously, and therefore the back-up is assured to the stand-by system from the working system. |
