Efficient Networks Siemens Sinamics S120 - Manual (Page 424)

Communication PROFIBUS DP/PROFINET IO
10.2 Communication via PROFIBUS DP
Drive Functions
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Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4
10.2.4.3 Activating/parameterizing slave-to-slave communications
The "slave-to-slave communications" function must be activated both in the publishers as
well as in the subscribers, whereby only the subscriber is to be configured. The Publisher is
automatically activated by the bus system when booting.
Activation in the Publisher
The master is informed abut which slaves are to be addressed as publishers with a different
layer 2 function code (DXB request) via the configuration of the subscriber links.
The publisher then sends its input data not only to the master but also as a broadcast
telegram to all bus nodes.
These settings are made automatically by the S7 software.
Activation in the Subscriber
The slave, which is to be used as Subscriber, requires a filter table. The slave must know
which setpoints are received from the master and which are received from a publisher.
STEP7 automatically generates the filter table.
The filter table contains the following information:
● Address of the publisher
● Length of the process data
● Position (offset) of the input data
● Amount of data
● Target of the data
Parameterizing telegram (SetPrm)
The filter table is transferred, as dedicated block from the master to the slave with the
parameterizing telegram when bus communications are established.
Configuring telegram (ChkCfg)
Using the configuration telegram, a slave knows how may setpoints are to be received from
the master and how many actual values are to be sent to the master.
For slave-to-slave communications, a special space ID is required for each tap. The
PROFIBUS configuration tool (e.g. HW Config) generates this ID and then transferred with
the ChkCfg in the drives that operate as Subscribers.