Technical data

The Master Mode – Commands, Sequence, Programming
4-2
SIMATIC NET AS-Interface – Introduction and Basic Information
C79000-G8976-C089/03
4.1 Master-Slave Principle
How the AS-Interface Operates
The AS-Interface operates on the master-slave principle. This means that the AS-i
master connected to the AS-i cable controls the data exchange with the slaves via
the interface to the AS-i cable.
The following diagram illustrates the two interfaces of the AS-i master CP.
S The process data and parameter assignment commands are transferred via the
interface between the master CPU and the master CP.
The user programs have suitable function calls and mechanisms available for
reading and writing via this interface.
S Information is exchanged with the AS-i slaves via the interface between the
master CP and AS-i cable.
PLC / PC
CPU
I/O
Configuration
Address
AS-i cable
AS-i slave
User
program
AS-i master
CP
Interface to the user
program
Para-
meters
Figure 4-1