Efficient Networks S120 manual Activating/parameterizing slave-to-slave communications

Communication PROFIBUS DP/PROFINET IO 10.2 Communication via PROFIBUS DP

10.2.4.3Activating/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.

424	Drive Functions
	Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4