How The User Program Addresses The As-I Slaves; Addressing As-I User Data - Siemens SIMATIC NET CP 142-2 Manual

B8976111/02
3.2

How the User Program Addresses the AS-i Slaves

3.2.1 Addressing AS-i User Data

Each slave on the AS-i cable is assigned four bits (a nibble) of input data and four bits of output data
by the CP 142-2. This nibble can be written (slave output data) and read (slave input data). This
allows bi-directional slaves to be accessed.
In total, the maximum of 31 AS-i slaves occupy 16 bytes of input data and 16 bytes of output data
(see table below).
When using the CP with the BM141/BM142, the start addresses m and n of the input or output
±
data depend on the configuration of the PROFIBUS DP master.
When using the CP with the BM147, the start addresses depend on the slot of the CP (see
±
Section 3.1.2). The values m and n are then always the same.
Assignment of the input data of the slaves
Byte Number
m+0
m+1
m+2
m+3
m+4
m+5
m+6
m+7
m+8
m+9
m+10
m+11
m+12
m+13
m+14
m+15
m = start address of the input data
Bits 7-4
Reserved for FC "ASI_3422" Slave 1
Slave 2
Slave 4
Slave 6
Slave 8
Slave 10
Slave 12
Slave 14
Slave 16
Slave 18
Slave 20
Slave 22
Slave 24
Slave 26
Slave 28
Slave 30
Bit 3 | Bit 2 | Bit 1 | Bit 0
Bits 3-0
Bit 3 | Bit 2 | Bit 1
Slave 3
Slave 5
Slave 7
Slave 9
Slave 11
Slave 13
Slave 15
Slave 17
Slave 19
Slave 21
Slave 23
Slave 25
Slave 27
Slave 29
Slave 31
Bit 3 | Bit 2 | Bit 1
3-2
AS-i Master Module CP 142-2
| Bit 0
| Bit 0