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S5-95F
12.3.2 Programming Interrupt Responses in OB3
Interrupt-driven program scanning is possible only when the following prerequisites have been
fulfilled:
•
Interrupt inputs have been enabled in DB1.
•
The programmable controller must be in the "POWER ON" state and set to "RUN".
•
Interrupt processing must not have been disabled via an "IA" statement (see section 8.2.8).
•
OB3 must have been programmed.
Example for Programming OB3
A negative edge at interrupt input I 33.5 triggers an interrupt.
When this occurs,
•
OB3 is invoked, if programmed, and
•
Bit 63.5 in IB 63 is set to "1", even if OB3 has not been programmed.
Table 12-7. Example for Scanning the Diagnostic Bytes to Determine the
Example
The OB3 interrupt
processing routine in FB10
is to be executed in the
event of an interrupt at I
33.5
Note
The diagnostic bits in IB 61 ... IB 63 must be reset to "0" immediately following
execution of the interrupt processing routine, at the latest. The system resets the bits
when the next interrupt is generated.
EWA 4NEB 812 6210-02
Cause of an Interrupt
STL
OB3
Interrupt at I 33.5
A I 63.5
Reset diagnostic bit I 63.5
R I 63.5
Execute program (response to interrupt) in
JC FB 10
.
FB10
.
.
BE
Interrupt Processing
Explanation
12-13
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