Technical data

User interface: OB 9 OB 9 is called as the user interface for a clock-driven time interrupt.
You store a STEP 5 program in OB 9 that is to be processed whenever
it is called. If you do not load OB 9, program execution is not
interrupted.
Interruptions The execution of a clock-controlled time interrupt can be interrupted
at
block boundaries, or operation boundaries (if selected in DX 0) by
the following:
•• processing of a process interrupt
•• processing of a delay interrupt
•• processing of a closed loop controller interrupt.
The processing can be interrupted at
operation boundaries or aborted
completely by the following:
•• the occurrence of a hardware fault or program error,
•• operator intervention (PG function, stop switch, MP-STP),
•• the stop operation.
Special features
•• A clock-driven time interrupt is only processed in the RUN mode.
Clock-driven time interrupts that occur in the STOP mode, when
the power has failed or during RESTART are
discarded providing
the trigger time did not occur during STOP (see above).
•• A clock-driven time interrupt generated following OVERALL
RESET and COLD RESTART (= OB 151 call) is retained during
a WARM RESTART and following POWER OFF/POWER ON,
providing the trigger time did not occur during STOP (see above).
•• If you generate a new clock-controlled time interrupt, i.e. you call
OB 151 with new timer values, an already existing clock-driven
time interrupt is cancelled. A currently active clock-driven
interrupt is continued. Only
one clock-driven time interrupt is ever
valid at one time.
•• If a clock-driven time interrupt occurs when a previous
clock-driven time interrupt has not been processed or not been
completely processed, the new time interrupt is discarded.
Clock-driven time interrupts are not checked for collisions.
•• You can use the special functions OB 120 and OB 122, to disable
or delay the processing of clock-driven time interrupts.
RUN Mode
CPU 928B Programming Guide
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