Disable/Enable Interrupt, For Cpu 103 Version 8Ma02 And Higher - Siemens S5-100U User Manual

S5-100U
8.2.8

Disable/Enable Interrupt, for CPU 103 Version 8MA02 and Higher

The disable/enable interrupt operations affect interrupt-driven and time-controlled program scanning.
They prevent process or time interrupts from interfering with the processing of a sequence of state-
ments or blocks. Table 8-18 lists the disable/enable interrupt operations. An example follows the
table.
Operation Operand
IA
RA
Processing
Execution of the disable/enable interrupt operations does not depend on the RLO. These operations
do not affect the RLO or the condition codes. After the "IA" statement is processed, no more
interrupts are executed. The "RA" statement cancels the effect of "IA".
Example
Disable interrupt processing in a
specific program section and then
enable it again.
EWA 4NEB 812 6120-02
Table 8-18. Disable/Enable Interrupt Operations
Disable interrupt
Enable interrupt
=
IA
A
JU
RA
Meaning
STL
.
.
.
.
.
Q 1.0
Disable interrupt.
I 0.0
.
.
.
If an interrupt occurs, the program
FB 3
section between the "IA" and
.
"RA" is scanned without
.
interruption.
.
Enable interrupt.
Interrupts that occurred in the
.
meantime are processed after the
.
"RA" operation.
.
STEP 5 Operations
Explanation
8-53