Ob 122: "Disable Interrupts" On/Off - Siemens CPU 948 Programming Manual

Simatic s5 s5-155u
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OB 122: "Disable Interrupts" On/Off

6.3

OB 122: "Disable Interrupts" On/Off

Function
Parameters
6 - 12
A STEP 5 program can be interrupted at block boundaries or operation
boundaries by programs at an execution level with a higher priority.
The program execution levels with higher priority include the
following:
• • TIMED INTERRUPTS
and
• • PROCESS INTERRUPTS.
The time required to run the interrupted programs is expanded by the
run time of the nested programs.
Using OB 122, you can prevent interrupt servicing blocks being
nested at one or more consecutive block or operation boundaries.
OB 122 influences the acceptance of interrupts:
• • "Disable interrupts" on means the following:
no interrupts will be registered from now on.
• • "Disable interrupts" off means the following:
all interrupts occurring will be registered from now on and the
corresponding blocks will be nested and executed at the next
operation or block boundary (depending on the mode set in DX 0).
Interrupts that have already been registered, are then no longer
serviced if the mode "interruptability at block boundaries" is set in
DX 0.
ACCU-1-L
Function no.,
Permitted values:
1 = disable all interrupts
2 = enable all interrupts
CPU 948 Programming Guide
C79000-G8576-C848-04

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