Media Redundancy; Rt Classes For Profinet Io - Siemens SINAMICS S120 Function Manual

Communication
11.3 Communication via PROFINET IO
Note
Routing is not possible between the two interfaces.
11.3.2.1

Media redundancy

To increase the availability of PROFINET, you can create a ring topology. If the ring is
interrupted at one point, the data paths between the devices are automatically reconfigured.
Following reconfiguration, the devices can once again be accessed in the resulting new
topology.
To create a ring topology with media redundancy, route the two ends of a line-type
PROFINET topology to a switch which serves as redundancy manager (e.g. a suitable
SCALANCE switch). Closing the linear bus topology is realized using two ports (ring ports) of
the SCALANCE redundancy manager, which monitors the data telegrams in the PROFINET
ring. All other connected PROFINET nodes are redundancy clients.
The Media Redundancy Protocol (MRP) is the standard procedure for media redundancy.
Using this procedure, a maximum of 50 devices can participate in each ring. In the case of
an interrupted cable, data transfer is only briefly interrupted as the system switches over to
the redundant data path.
If a short-term interruption is not permitted, data transfer must be set to IRT High
Performance. The uninterruptible MRRT is automatically set. A SIMOTION controller (or
another suitable controller) is required in this case.
The two integrated PROFINET IO interfaces of the Control Units CU320-2 PN and CU310-2
PN can be configured as redundancy clients.
From a CBE20, only the first two ports are capable of establishing a ring topology. Routing
between the integrated PROFINET IO interfaces and a CBE20 is not possible.
11.3.3

RT classes for PROFINET IO

PROFINET IO is a scalable realtime communication system based on Ethernet technology.
The scalable approach is expressed with three realtime classes.
RT
RT communication is based on standard Ethernet. The data is transferred via prioritized
Ethernet telegrams. Because standard Ethernet does not support any synchronization
mechanisms, isochronous operation is not possible with PROFINET IO with RT!
The real update cycle in which cyclic data is exchanged depends on the bus load, the
devices used and the quantity framework of the I/O data. The update cycle is a multiple of
the send cycle.
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Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
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