Siemens SIMATIC S5-115U, Руководство пользователя

Страница: 160 / 676

Addressing/Address Assignments S5-115U Manual
6.3.1 Accessing the PII
At the beginning of program scanning, the input module signal states are written to the PII. The
statements in the control program use a particular address to indicate what information is
currently needed. The control logic then reads the data that was current at the beginning of pro-
gram scanning and works with it.
15
15
PII
Reading bit by bit
in binary operations:
A I 2.2
7 6 5 4 3 2 1 0
Bit No.
Byte 2
a a a a
a a a a
a a a a
a a a a
High-Order
Byte
(Value 00
H
)
0
Reading byte by byte
when loading into ACCUM 1:
L IB 12
Byte 12
Reading word by word
when loading into
ACCUM 1:
L IW 40
a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a
Low-Order
Byte
0
Byte 40
Byte 41
ACCUM 1
High-Order
Byte Low-Order
Byte
ACCUM 1
Figure 6-8. Accessing the PII
Reading of the PII can be inhibited.
To do so, it is necessary to act upon bit 1 of system data word SD 120 (EAF0
H
) using system
operations (Load and Transfer).
Bit 1="1": Reading of inputs is inhibited.
Bit 1="0": Reading of inputs is enabled.
The default setting is bit 1="0" (read enabled).
Note
System data word SD 120 can be modified with the programmer function DISPL. ADDR.
only when the PLC is in the STOP mode!
6-8
EWA 4NEB 811 6130-02b