| 摘要 |
PURPOSE:To effectively detect the abnormality not only in the hardware but also in the software of a computer and to rapidly change over the operating computer by using the overflow signal of a watch dog timer. CONSTITUTION:A present system computer A operates, and when the abnormality is generated in a program or the like with its online contact 12A closed, the counter of the watch dog timer 2 overflows and an alarm signal is inputted to a system change over device 1 through a driver 3A. Thereby, an abnormality detecting contact 14A in the system change over device is closed and a present system abnormality detecting signal is outputted from an output line 11A. Based on this signal, in the system change over device 1, the separating signal of a common bus 7A and an I/O equipment 8 is fed to a present system common bus connection device 6A and the connection signal of a common bus 7B and the I/O equipment 8 is fed to the common bus connection device 6B of a standby system. When these change over is completed, a change over completion signal is transmitted to the computer 100 of the standby system through a receiver 4B.
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