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4.4.4
Interrupt-Driven Program
Execution
PROCESS INTERRUPTS via
input byte IB 0
Triggering
User interfaces
OB 2 to OB 9
CPU 948 Programming Guide
C79000-G8576-C848-04
Depending on the selected mode, two different types of interrupt-driven
program execution are possible with the CPU 948:
• • PROCESS INTERRUPTS
via input byte IB 0 (max. 8 interrupts),
• • INTERRUPTS
via signal lines of the S5 bus (max. 4 interrupts).
To service process interrupts, the default "process interrupts via IB 0 =
on" must not be changed in the data block DX 0.
Program execution controlled by process interrupts means that a
signal change in the input byte IB 0 causes the current program
execution to be interrupted and a special program section to be
executed.
Note
If you enable "servicing process interrupts via IB 0" you cannot
use the delayed interrupt, the time-controlled interrupt and the
system interrupt.
The signal state change of a bit in input byte IB 0 triggers the process
interrupt.
If a process interrupt occurs, one of the OBs listed in the following
table is called as the user interface.
Table 4-7
User interfaces for process interrupts
Signal state change in IB 0 with bit
I 0.0
I 0.1
I 0.2
I 0.3
I 0.4
I 0.5
I 0.6
I 0.7
RUN Mode
OB called
OB 2
OB 3
OB 4
OB 5
OB 6
OB 7
OB 8
OB 9
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