| 摘要 |
PURPOSE:To make a device compact by detecting the runaway of an arithmetic processor, inputting an interruption, determining an output signal from the processor at a safety side level, and supplying the output signal to an output circuit. CONSTITUTION:A central processing unit(CPU) 3 controls the operation of the whole device, executes a sequence program stored in a built-in RAM 5 and executes the automatic control of an electronic apparatus. A monitoring timer 6 is functioned as a watchdog timer to detect the abnormality of the CPU 3, and when time-up is generated, inputs an interrupt to the CPU 3. Receiving the interruption input, the CPU 3 transfers a current program reading address to the leading storing address of an interruption program stored in a built-in program memory 4. Consequently the CPU 3 sends an OFF signal to the output circuit 11 through an I/O port 8. Consequently an exclusive reset signal line and an external timer can be made unnecessary and the device can be made compact. |
