Siemens DP/AS-Interface Link 20E Manual page 51

Example of a Configuration
Figure 2-2 shows an example of the PROFIBUS DP master addressing four AS-i
slaves. In the DP master, the start addresses m = 0 are used for the I/O data.
The bits relevant for the user program (existing AS-i slaves) are shown on a gray
background. The bits shown on a white background are irrelevant for the user
program since no AS-i slaves are assigned here.
DP master
32
Input bytes
0
Bit 3 Bit 2 Bit 1
Bit 0
slave 2
1
Bit 3 Bit 2 Bit 1 Bit 0
slave 4
2
Bit 2 Bit 1 Bit 0
. Bit 3
.
.
Slave 30B
31
Bit 3 Bit 2 Bit 1 Bit 0
4
7 6 5
Slave no. 2
AS-i slaves
4 I module
4 I module
Figure 2-2
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
DP/AS-Interface Link 20E
Release 11/2002
C79000-G8976-C138–04
Data Exchange Between the DP Master and AS-i Slave
slave 1
Bit 3 Bit 2 Bit 1 Bit 0
slave 3
Bit 3 Bit 2 Bit 1
Bit 0
slave 5
Bit 1 Bit 0
Bit 3 Bit 2
Slave 31B
Bit 3 Bit 2 Bit 1 Bit 0
3 2 0
1
Slave no. 3
2 I/2 O module
Terminal 2 on the AS-i bus
module
Terminal 1 on the AS-i bus
module
32
Output bytes
slave 1
0
Bit 0
Bit 3 Bit 2 Bit 1 Bit 3 Bit 2 Bit 1
slave 2 slave 3
1
Bit 3 Bit 2 Bit 1 Bit 0 Bit 3
Bit 2 Bit 1
slave 4
slave 5
2
Bit 2
Bit 3 Bit 0 Bit 3 Bit 1
Bit 1 Bit 2
.
.
.
Slave 30B Slave 31B
31
Bit 2 Bit 1 Bit 0
Bit 3 Bit 3 Bit 2
Bit 1
6 5
7 4
Slave no. 4 Slave no. 31B
4 O module 4 I/3 O module
1
Bit 0
Bit 0
Bit 0
Bit 0
0
0 Bit no.
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