Efficient Networks S120 Slave-to-slave communications, General information Description, Publisher

Communication PROFIBUS DP/PROFINET IO 10.2 Communication via PROFIBUS DP

10.2.4Slave-to-slave communications

10.2.4.1General information

Description

For PROFIBUS-DP, the master addresses all of the slaves one after the other in a DP cycle. In this case, the master transfers its output data (setpoints) to the particular slave and receives as response the input data (actual values). Fast, distributed data transfer between drives (slaves) is possible using the "slave-to-slave communications" function without involving the master.

The following terms are used for the functions described here:

●Slave-to-slave communications

●Data Exchange Broadcast (DXB.req)

●Slave-to-slave communications (is used in the following)

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Figure 10-29 Slave-to-slave communications with the publisher-subscriber model

Publisher

With the "slave-to-slave communication" function, at least one slave must act as the publisher.

The publisher is addressed by the master when the output data is transferred with a different layer 2 function code (DXB.req). The publisher then sends its input data to the master with a broadcast telegram to all bus nodes.

Drive Functions	421
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4