JPS57182255A - Preventing device for runaway of computer - Google Patents

Abstract

PURPOSE:To prevent an accident due to a runaway by providing a program for reinitializing a timer before the time-up of the timer, and then powering down a computer by putting the timer in a time-up state when a soft program enters into a runaway. CONSTITUTION:The command signal output of a microcomputer (mu computer)1 turns on and off relays 9 and 10, whose contacts 9a and 10b are placed in the opposite states to each other; and a timer 7 initializes its timer value at every switching period T1 of the contacts 9a and 10b, and the contacts 7a1, 7a2, and 7b of the timer 7 never operate to continuously power up the power source unit 2 of the mu computer 1 through an operating relay 6. If the program execution of the mu computer 1 becomes abnormal and command outputs to the relays 9 and 10 are not switched any more,the timer 7 enters into a time-up state without being initialized, and then a pilot lamp 8 turns on through the contact 7a1 while the relay 6 is released through the contact 7b to power down the power source unit 2, so the mu computer 1 is also powered down, stopping the runaway of a body to be controlled.