Technical data

6.5 OB 120: Enabling/Disabling of Interrupts
A STEP 5 program can be interrupted at block or operation
boundaries by programs with a higher priority. These higher priority
program processing levels include the process and all time interrupts
(cyclic time interrupts, clock-driven time interrupt and delay
interrupt). The runtime of the interrupted program is therefore
extended by the runtime of the programs inserted by the interrupts.
Using special function organization blocks OB 120, you can prevent
the insertion of higher priority program processing levels at one or
more consecutive block or operation boundaries (depending on the
setting in DX 0).
Function The special function organization OB 120 affects the reaction to
interrupts:
Disabling interrupts means that no more interrupts are recognized and
the interrupts that have already been detected (e.g. they are waiting for
a block boundary) are cleared. If OB 2 (process interrupts) or an OB
for time-driven interrupt processing have already started, they are
processed to the end.
Enabling interrupts means that all interrupts are once again
recognized immediately, and are inserted and processed at the next
block or operation boundary.
Parameters 1. Double control word
OB 120 records the interrupts to be disabled or delayed in a
system-internal
double control word.
Bit no. 31 3 2 1 0
Double control word
OB 120: Enabling/Disabling of Interrupts
CPU 928B Programming Guide
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