Siemens S5-100U - Disable;Enable Interrupt, for CPU 103 Version 8 MA02 and Higher

S5-100U STEP 5 Operations
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.
Table 8-18. Disable/Enable Interrupt Operations
Operation MeaningOperand
IA Disable interrupt
Enable interruptRA
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”.
STL ExplanationExample
Disable interrupt processing in a
specific program section and then
enable it again.
.
.
.
.
.
= Q 1.0
IA
A I 0.0
.
.
.
JU FB 3
.
.
.
RA
.
.
.
Disable interrupt.
If an interrupt occurs, the program
section between the “IA” and
“RA” is scanned without
interruption.
Enable interrupt.
Interrupts that occurred in the
meantime are processed after the
“RA” operation.
EWA 4NEB 812 6120-02 8-53