| 摘要 |
PURPOSE:To prevent the runaway of a program securely by stopping the driving of a program by an arithmetic processor when the abnormality of a clock pulse or power source is detected. CONSTITUTION:When the abnormality detecting circuit 4 for an AC power source 3 sends a signal REST-1 to a CPU2 with the signal MP (memory protection) of software 1 which receives its signal PFD (power fail down), a signal RESET-2 is inputted to an OR circuit 9 together with the signal RESET-1 by connecting the power source 3 to a waveform shaping circuit 7, counter 6, and an FF8, and its signal RESET-12 is outputted to the CPU2. Further, an oscillator 10 which allows the CPU2 to generate a clock pulse for the operation of the software 1 is provided, and its pulse signal is outputted from the CPU2 to a counter 6 to clear a count value. Consequently, the signal RESET-12 is sent out in response to the oscillation abnormality of the oscillator 10 as well as the abnormality of the power source 3. |
