Technical data

4.5.2
Time-Driven Program
Execution
Time-driven processing occurs when a time signal from a clock or
internal clock pulse prompts the CPU to interrupt the current program
and execute a specific program. After executing this program, the
CPU returns to the point at which the previous program was
interrupted and continues execution. This way, particular program
sections can be inserted automatically into the cyclic program at a
specified time.
You can trigger time-driven program execution in different ways, as
follows:
•• One-off triggering after a freely selectable delay time in the
millisecond range, a "
delay interrupt" (DELAY INTERRUPT
program processing level). The OB 6 organization block is called
via this interrupt.
•• Triggering using a freely selected time base or once only at an
absolute time, a "clock-driven time interrupt" (program processing
level TIMED JOB). This interrupt calls organization block OB 9.
•• Triggering in 9 different time bases with a range from 10 ms to 5
seconds by "time interrupts" (program processing levels TIME
INTERRUPTS). An organization block (OB 10 to OB 18) is
assigned to each time interrupt. These have a fixed cycle, i.e. the
time between two program starts is fixed.
Delay interrupt (from
Version -3UB12)
Small time intervals with a resolution of 1 ms can also be specified
with the delay interrupt of the CPU 928B. When the set time has
elapsed, the system program calls OB 6
once.
Resolution A delay interrupt is generated by calling the special function
organization block OB 153 (see Section 6.12). As soon as the delay
time parameterized with OB 153 has elapsed, the system program
interrupts the current program execution and calls OB 6. After this,
program execution is resumed at the interrupt point.
User interface OB 6 In the case of a delay interrupt, OB 6 is called as the user interface. In
OB 6 you store a STEP 5 program to be executed in this case. If OB 6
has not been loaded, program execution will not be interrupted.
4
RUN Mode
CPU 928B Programming Guide
C79000-B8576-C898-01
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