Siemens CP 243-2 - Manual (Page 54)

Access to the Data of the AS-i Slaves
3-6
SIMATIC NET CP 243-2 AS-i Master
C79000-G8976-C142/02
Example
Figure 3-1 shows an example of the CP 243-2 addressing four AS-i slaves. In the
example, m = 0 is the start address for the input data and n = 0 is the start address
for the output data.
The bits relevant for the user program (existing AS-i slaves) are shown on a gray
background. The bits on a white background are irrelevant for the user program.
CP 243-2
16 input bytes
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
1
.
.
.
15
.
.
.
4 I module
Slave no. 2 Slave no. 3 Slave no. 4 Slave no. 31 AS-i slaves
4 I module 4 I/4 O module 2 I/2 O module 4 O module
2
15
0 0
1
2
Slave 1 Slave 1
Slave 2 Slave 3
Slave 30 Slave 31
Slave 4 Slave 5
Slave 2 Slave 3
Slave 4 Slave 5
Slave 30 Slave 31
Bit 0 Bit 1 Bit 2 Bit 3
Bit 0
Bit 0
Bit 0
Bit 0
Bit 0
Bit 0
Bit 0 Bit 0
Bit 0
Bit 0 Bit 0
Bit 0 Bit 0
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 1
Bit 3
Bit 2
Bit 2 Bit 2
Bit 2
Bit 2 Bit 2
Bit 2
Bit 2
Bit 2
Bit 2
Bit 2
Bit 2
Bit 2
Bit 2
Bit 3
Bit 3
Bit 3
Bit 3
Bit 3
Bit 3
Bit 2
Bit 3 Bit 3
Bit 3
Bit 3
Bit 3 Bit 3
Bit 3
Bit 3 Bit 1 Bit 0 Bit 1 Bit 0
output bytes 16
Figure 3-1
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 bus modules to the data bits of the
input/output bytes is shown below based on the example of slave number 3:
1 0 Bit no.
Input byte 1
Terminal 1 on the AS-i bus module
Terminal 2 on the AS-i bus module
3 2 Bit no.
Output byte 1
Terminal 3 on the AS-i bus module
Terminal 4 on the AS-i bus module