Siemens SINAMICS DCM Operating Instructions Manual page 428

Descriptions of functions
10.4 Communication via PROFIBUS DP
● Master
Masters are categorized into the following classes:
– Master class 1 (DPMC1):
– Master class 2 (DPMC2):
● Slaves
With respect to PROFIBUS, the SINAMICS drive unit is a slave.
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
transferred 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...24] 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 in the project navigator under "Drive unit" >
"Communication" > "Telegram configuration".
When you create the configuration on the controller side (e.g. HW Config), the process-data-
capable drive objects for the application are added to the telegram in this sequence.
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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
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
SINAMICS DCM Control Module
Operating Instructions, 12/2018, A5E34888669A