6.11 OB 142: "Delay All Interrupts" On/Off
A STEP 5 program can be interrupted at block or operation boundaries
by programs with a higher priority. The process interrupts and all
timed interrupts belong to these higher priority program execution
levels. The runtime of the interrupted program is extended by the
runtime of the nested programs. Using OB 142, you can prevent the
nesting of higher priority program execution levels at one or more
consecutive block or operation boundaries (depending on the setting
in DX 0).
Function
OB 142 affects the servicing of interrupts:
"Delay interrupts" on means that all interrupts occurring are registered
and pending interrupts remain registered. The registered interrupts are,
however, initially not serviced. The operation or block boundaries for
servicing interrupts are temporarily made ineffective. If an OB for process
interrupt servicing or an OB for timed interrupt servicing has already
started, this is processed completely.
"Delay interrupts" off means that all registered interrupts are processed at
the next block or operation boundary.
Note
The time in which the interrupts are delayed must be shorter than
three times the value of the shortest timed interrupt period. If
this is not the case, a collision of timed interrupts occurs.
Parameters
1. Control word
OB 142 enters the interrupts to be delayed in a system-internal control
word, as follows:
Bit no. 15 0
C o n t r o l w o r d
OB 142: "Delay All Interrupts" On/Off
CPU 948 Programming Guide
6 - 32 C79000-G8576-C848-04
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