Technical data

Interrupt points Closed loop control processing can be interrupted either at block
boundaries
(default) or at operation boundaries (programmed in
DX 0), by the following:
•• processing of a process interrupt,
•• processing of a delay interrupt.
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 STP.
4.5.4
PROCESS INTERRUPT:
Interrupt-Driven Program
Execution
Interrupt-driven program execution involves the S5 bus signal of an
interrupt-capable digital input module (e.g. 6ES5 432-4UAxx) or a
suitable IP module that causes the CPU to interrupt program
execution and to process a specific program section. On completion of
this program, the CPU returns to the point at which execution was
interrupted and continues from there.
The evaluation of a process interrupt can be triggered either by a
signal level or signal edge. You can write a program to either disable,
delay or enable the interrupt. OB 2 can interrupt the current program
either at
operation or block boundaries (when you program DX 0).
Triggering The active state of an interrupt line on the S5 bus triggers the process
interrupt. Depending on the slot in the rack, each CPU is assigned one
of the interrupt lines (for more detailed information, refer to Chapter 4
in the System Manual).
User interface OB 2 When a process interrupt occurs, OB 2 is called as the user interface.
In OB 2, you program a specific program to be processed if a process
interrupt occurs.
If OB 2 is
not programmed, the cyclic program is not interrupted. No
interrupt-driven program execution takes place.
4
RUN Mode
CPU 928B Programming Guide
C79000-B8576-C898-01
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