Siemens SIMATIC NET CP 343-2, Руководство пользователя

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4 Data Exchange between User Program and AS−i Slaves
48
CP 343−2 / CP 343−2 P AS−Interface Master
Release 08/2008
C79000−G8976−C149−04
PLC CPU
AS-i
slave 2
AS-i
slave 1
AS-i
slave n
Analog
slaves
ÍÍÍ
ÍÍÍ ÎÎÎ
ÎÎÎ
AS-Interface
write_record
S
DSNR 140−147
Data area for
analog
output values
Data area for
analog input
values
read_record
S
DSNR 140−147
ÍÍÍ
ÍÍÍ ÎÎÎ
ÎÎÎ
ÍÍÍ
ÍÍÍ ÎÎÎ
ÎÎÎ
Data records
140−147 for
analog
values
outputs
Data records
140−147 for
analog
values inputs
ÍÍÍÍ
ÍÍÍÍ
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
CP 343-2
Figure 4-4
4.4.1 Addressing Analog Values of AS-i Slaves
Mapping the Analog Values in the Data Records
For each data record number, you can use data record lengths between 2 bytes
and max. 128 bytes.
An 8-byte area is used for each slave address to address four analog channels.
Table 4-3 below shows which data record is used to transfer the analog values of
which AS-i slave. The way in which the analog values of the analog slave are
arranged is shown in Table 4-4.
The tables can be used both for the analog
inputs
and for the analog
outputs
.