工业控制机在工业现场使用时,大量的干扰源虽不会造成硬件系统的损坏,但常常使工业控制机不能正常运行,甚至控制失灵,造成严重后果。微机受干扰后,最常见的问题是程序执行进入一种“跑飞”或“死机”状态,引起程序失控。防止程序运行失控的主要对策是能及时发现程序运行的失控并引导系统正常运行。目前常用的方法是设置一个监视跟踪定时器,定时时间稍大于主控程序正常运行的一个循环周期,让主控程序运行过程中执行一次定时器的刷新操作。这样只要程序正常运行,定时器就不会产生溢出信号而发生中断。但当程序“跑飞”失控后,不能刷新定时器,导致定时器溢出产生中断,再利用定时中断服务程序将系统复位,重新初始化,重新执行主控程序或进入错误处理程序。这种方法在微机监测系统中,效果是明显的,但在某些工业控制系统中,特别在一些生产过程或流水线中,由于生产过程或工序的逻辑顺序性,当程序失控后,常要求系统 Industrial control machine in the industrial site, a large number of sources of interference will not cause damage to the hardware system, but often make the industrial control machine can not operate normally, and even control failure, resulting in serious consequences. After the computer is disturbed, the most common problem is that the program execution enters a state of “running off” or “crashing”, causing the program to run out of control. The main countermeasure to prevent the program from running out of control is to discover the out-of-control of the program running and guide the normal operation of the system in time. At present, a commonly used method is to set a monitoring and tracking timer, the timing time is slightly larger than one cycle of the normal operation of the master program, so that the master program runs and executes a timer refresh operation. So long as the program is running normally, the timer will not produce the overflow signal and cut off. But when the program “runaway” out of control, can not refresh the timer, resulting in timer overflow interrupt, and then use the timer interrupt service routine to reset the system, reinitialize, re-execute the master program or enter the error handler. This method in the computer monitoring system, the effect is obvious, but in some industrial control systems, especially in some production processes or assembly line, due to the logical sequence of the production process or process, when the program out of control, often require the system