Accessing The Interrupt Piq - Siemens SIMATIC S5-100U System Manual

Addressing
6.6.2

Accessing the Interrupt PIQ

When accessing the interrupt PIQ, the following rules apply.
• Data can be written to the interrupt PIQ only within time-controlled or interrupt-driven program
processing.
• Data from a time-controlled or interrupt-driven program to external outputs is written during time-
controlled or interrupt-driven program processing both to the "normal" PIQ and the interrupt
PIQ.
• Data from the interrupt PIQ is read out to the outputs in the next interrupt output data cycle.
• The PIQ is copied to the interrupt PIQ after the OB1 program cycle.
Note
The interrupt output data cycle is executed only after the interrupt PIQ has been written
to.
Access to the interrupt PIQ is expressed by the "PB" or "PW" operand identifiers in a statement in
the time-controlled or interrrupt-driven program.
The letter "T" identifies the "Transfer" operation (see chapter 8).
• Byte-by-byte writing
"PB <byte address>"
Example: Writing signal states to all
channels of an 8-channel digital output
module in slot 13
ACCU 1
• Word-by-word writing
"PW <word address>"
Example: Writing an analog value to channel 3
of a 4-channel analog output module in slot 5
ACCU 1
6-14
T PY 13
15
High byte Low byte
T PW 110
15
High byte Low byte
Figure 6-11. Accesses to the Interrupt PIQ
Interrupt PIQ
Byte 13
0
Byte 110
Byte 111
0
EWA 4NEB 812 6120-02b
S5-100U