Technical data

The Master Mode – Commands, Sequence, Programming
4-8
SIMATIC NET AS-Interface – Introduction and Basic Information
C79000-G8976-C089/03
Initialization mode
The initialization mode, also known as the offline phase, sets the basic status of
the master. The module is initialized after switching on the power supply or
following a restart during operation. During the initialization, the images of all the
slave inputs and the output data from the point of view of the application are set to
the value “0” (inactive).
After switching on the power supply, the configured parameters are copied to the
parameters field so that the subsequent activation uses the preset parameters. If
the AS-i master is reinitialized during operation, the values from the parameters
field which may have changed in the meantime are retained.
Startup Phase
S Detection phase: Detection of AS-i slaves in the startup phase
During startup or after a reset, the AS-i master runs through a startup phase
during which it detects which AS-i slaves are connected to the AS-i cable and
what type these slaves are. The “Type” of the slaves is specified by the
configuration data stored permanently on the AS-i slave when it is
manufactured and can be queried by the master. Configuration files contain the
I/O assignment of an AS-i slave and the slave type (ID codes).
The master enters detected slaves in the list of detected slaves (LDS).
S Activation phase: Activating AS-i slaves
After the AS-i slaves are detected, they are activated by the master sending a
special call. When activating individual slaves, a distinction is made between
two modes on the AS-i master:
– Master in the configuration mode:
All detected stations (with the exception of the slave with address “0”) are
activated. In this mode, it is possible to read actual values and to store them
for a configuration (–> configuration mode).
– Master in the protected mode:
Only the stations corresponding to the expected configuration stored on the
AS-i master are activated. If the actual configuration found on the AS-i cable
differs from this expected configuration, this is indicated by the AS-i master.
The master enters activated AS-i slaves in the list of activated slaves (LAS).
S Normal mode
On completion of the startup phase, the AS-i master switches to the normal
mode.
– Data exchange phase
In the normal mode, the master sends cyclic data (output data) to the
individual AS-i slaves and receives their acknowledgment messages (input