Siemens SIMATIC NET CP 343-2 Manual page 41

Example of a Configuration
Figure 2−2 shows an example of the PLC CPU addressing 4 standard or A slaves.
The base addresses m = 256 for the I/O data are configured in STEP 7.
The bits relevant for the user program are shown on a gray background. The bits
shown on a white background are irrelevant for the user program since no AS-i
slave bits are assigned here.
DP master
16
Input bytes
256
Bit 3 Bit 2 Bit 1
slave 2
257
Bit 3 Bit 2 Bit 1 Bit 0
slave 4
258
. Bit 1
Bit 2
Bit 3
.
.
slave 30
271
Bit 3 Bit 2 Bit 1
7 6 5
Slave no. 2
AS-i slaves
4 I module
Figure 4-2
In the figure above, for example, the 2I/2O module (AS-i slave number 3 with two
inputs and two outputs) occupies bits 0 and 1 in input byte 1 and bits 2 and 3 in
output byte 1.
The assignment of the AS-i terminals of the AS-i bus modules to the data bits of
the input/output bytes is shown below based on the example of slave number 3:
Input byte 1
Output byte 1
Terminal 4 on AS-i bus module
Terminal 3 on AS-i bus module
CP 343−2 / CP 343−2 P AS−Interface Master
Release 08/2008
C79000−G8976−C149−04
4 Data Exchange between User Program and AS−i Slaves
slave 1
Bit 0
Bit 3
Bit 2 Bit 1 Bit 0
slave 3
Bit 3
Bit 2 Bit 1
Bit 0
slave 5
Bit 0
Bit 1 Bit 0
Bit 3 Bit 2
slave 31
Bit 3 Bit 2 Bit 1 Bit 0
Bit 0
4 3 2 0
1
Slave no. 3
2 I/2 O module
4 I module
Terminal 2 on AS-i bus module
Terminal 1 on AS-i bus module
16
Output bytes
slave 1
256 Bit 0
Bit 2 Bit 1 Bit 3
Bit 3 Bit 2
slave 2
1 slave 3
257
Bit 3 Bit 2 Bit 1 Bit 0 Bit 3
Bit 2
slave 4
slave 5
258
Bit 2
Bit 3 Bit 0 Bit 3
Bit 1 Bit 2
.
.
.
slave 30 slave 31
271
Bit 2 Bit 1 Bit 0
Bit 3 Bit 2
7
3 2
7 6 6 5 5 4
4
Slave no. 4 Slave no. 31
4 O module 4 I/4 O module
1
3 2
Bit 0
Bit 1
Bit 0
Bit 1
Bit 0
Bit 1
Bit 0
Bit 1
0
1 0
0 Bit no.
Bit no.
41