Technical data

Table Of Contents
SFCs for Handling Time-Delay Interrupts
System Software for S7-300/400 System and Standard Functions - Volume 1/2
10-2
A5E00709327-01
What Happens if...
The following table lists a number of different situations and explains the effect they
have on a time-delay interrupt.
If ... and ... Then ...
A time-delay interrupt is started
(by calling SFC 32 "SRT_DINT").
The time-delay interrupt has
already started.
The delay time is overwritten; the
time-delay interrupt is started
again.
The time-delay interrupt OB does
not exist at the time of the call.
The operating system generates
a priority class error (calls OB85).
If OB85 does not exist, the CPU
changes to STOP.
The interrupt is started in a startup
OB and the delay time elapses
before the CPU changes to RUN.
The call of the time-delay interrupt
OB is delayed until the CPU is in
the RUN mode.
The delay time has elapsed. A previously started time-delay
interrupt OB is still being
executed.
The operating system generates a
time error (calls OB80). If OB80
does not exist, the CPU changes
to STOP.
Warm Restart and Cold Restart
During a warm or cold restart, all the time-delay interrupt settings made in the user
program by SFCs are cleared.
Starting in a Startup OB
A time-delay interrupt can be started in a startup OB. To call the time-delay
interrupt OB, the following two conditions must be met:
The delay time must have elapsed.
The CPU must be in the RUN mode.
If the delay time has elapsed and the CPU is not yet in the RUN mode, the time-
delay interrupt OB call is delayed until the CPU is in the RUN mode. The time-
delay interrupt OB is then called before the first instruction in OB1 is executed.