| 摘要 |
PURPOSE:To prevent a program from runaway by monitoring the execution period of a processor executing prescribed arithmetic processing, executing abnormal processing when a prescribed time exceeds, and when longer time than said time exceed, executing stop processing. CONSTITUTION:A monitoring timer 2' including two timers monitors the program execution period. The setting times t1, t2 of the two timers are set up to t1<t2. If the program execution period t0 exceeds t1, a time-up signal is inputted to a terminal IN1 of the processor 1 and the processor is stopped at its operation by software. When a timer reset signal is not inputted even after passing the prescribed time and t0>t2 is formed, a time up signal is inputted to a terminal IN2 of the processor 1 and the processor 1 is stopped at its operation by hardware. Thus, the program is prevented from runaway and system down is also prevented. |
