General Interrupt Processing With Plc S5-155U - Siemens SIMATIC S5 Equipment Manual

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2.8 General Interrupt Processing with PLC S5-155U

The central processor of the programmable controller operates in two operating modes:
–S5–150U mode
–S5–155U mode
The two operating modes process interrupts differently.
Type of processing
Acquisition of the interrupt via
Acquisition of the interrupt at
Jumpers on CPU 946
Organization block
AF and AS commands affect
program
Effect of special function OB 122
Standard function blocks FB 38 and FB 39 must be used in the interrupt program since these
blocks save and load other temporary (system) data. These function blocks rnus[be used with the
same data block in all interrupt programs.
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Process interrupt
Input byte IBO
Block boundaries
X46 to X49 open
Yes
Yes
Operating Instructions
Interrupt
Interrupt lines
Instruction boundaries
(level-triggered)
X46 to X49 closed
No
Yes
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