JPS6431245A - System for supervizing time - Google Patents

Abstract

PURPOSE:To preferably execute the time supervizing with high accuracy by the use of the processor of comparatively low speed and to prevent the accuracy from being reduced to the time supervizing of the low accuracy by providing a hardware timer in which the time is renewed by one unit when a constant time passes over. CONSTITUTION:At the starting time of the time supervizing of respective channels, a time supervizing control part 50 writes the starting time value of a hardware timer 21 and a supervizing timer value to an area 200 of a channel corresponding provided in a control memory 122. During the time supervizing of the respective channels, the detection processing of a time-out is executed by comparing a difference between the time value and the starting time value shown by the hardware timer 21 and the supervizing timer value. When the time is renewed in the hardware timer 21, the timer supervizing control part 50 prior executes the detection processing of the time-out of a supervizing timer to the channel to execute a high accuracy supervision out of the respective channels. Concerning the time-out detection of the supervizing timer to the channel to executed a low accuracy supervision, it is executed when a signal line is processed to the channel to use the hardware timer 21.