Siemens SINAMICS S120 Function Manual page 406

Communication PROFIBUS DP/PROFINET IO
10.2 Communication via PROFIBUS DP
● Master
● Slaves
Bus access method
PROFIBUS uses the token passing method, i.e. the active stations (masters) are arranged in
a logical ring in which the authorization to send is received within a defined time frame.
Within this time frame, the master with authorization to send can communicate with other
masters or handle communication with the assigned slaves in a master/slave procedure.
PROFIBUS telegram for cyclic data transmission and acyclic services
Each drive unit that supports cyclic process data exchange uses a telegram to send and
receive all the process data. A separate telegram is sent in order to perform all the acyclic
services (read/write parameters) under a single PROFIBUS address. The acyclic data is
transmitted with a lower priority after cyclic data transmission.
The overall length of the telegram increases with the number of drive objects that are
involved in exchanging process data.
Sequence of drive objects in the telegram
On the drive side, the sequence of drive objects in the telegram is displayed via a list in
p0978[0...15] where it can also be changed.
You can use the STARTER commissioning tool to display the sequence of drive objects for a
commissioned drive system in online mode by choosing ––> "Drive unit" ––> "Configuration".
When you create the configuration on the master side (e.g. HW Config), the process-data-
capable drive objects for the application are added to the telegram in this sequence.
The following drive objects can exchange process data:
Drive object
● Active Infeed (A_INF)
● Basic Infeed (B_INF)
● Smart Infeed (S_INF)
● SERVO
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Masters are categorized into the following classes:
– Master class 1 (DPMC1):
Central automation stations that exchange data with the slaves in cyclic and acyclic
mode. Communication between the masters is also possible.
Examples: SIMATIC S7, SIMOTION
– Master class 2 (DPMC2):
Devices for configuration, commissioning, operator control and monitoring during bus
operation. Devices that only exchange data with the slaves in acyclic mode.
Examples: Programming devices, human machine interfaces
With respect to PROFIBUS, the SINAMICS drive unit is a slave.
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4
Drive Functions