Technical data

Clock-driven time interrupts

The CPU 928B has a battery-backed clock (central back-up via the

power supply of the central controller), which you can set and read

out using a STEP 5 program. Using this clock, you can execute a

program section time-driven.

While the delay interrupt is used for high-speed jobs, the clock-driven

time interrupt is especially suitable for processing one-off jobs or jobs

occurring

cyclically at large time intervals such as hourly, daily or

every Monday. When the set time is reached, the system program

calls OB 9.

Triggering

A clock-driven time interrupt (timed job) is generated by calling the

special function organization block OB 151 (see Section 6.10). Once

the time transferred to OB 151 (time of day, date) has been reached,

the timed job is processed. This can be programmed to occur once

(absolute time) or be repeated (time base). Once a job becomes due

for processing, the system program interrupts the current program and

calls OB 9 (program processing level TIMED JOB). Following this,

the program is resumed at the point at which it was interrupted.

Example:

You want to trigger a time interrupt at the

55th second every minute.

Setting using OB 151:

SECONDS:

JOB TYPE: 1 (every minute)

min

5’55 6’55 7’55

Call OB 9 Call OB 9 Call OB 9

Generate

(call OB 151)

clock-driven

time interrupt

RUN Mode

CPU 928B Programming Guide

C79000-B8576-C898-01

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