Siemens SINAMICS DCM Manual page 474

10.5.3.1 Media redundancy
To increase the availability of PROFINET, you can create a ring topology for redundancy
purposes. 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 into one device, the SCALANCE device. Closing the linear bus
topology is realized using two ports (ring ports) of the SCALANCE device. The Scalance
device is the redundancy manager. The redundancy manager monitors the data telegrams in
the PROFINET ring. All other connected PROFINET nodes are redundant 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.
From a CBE20, only the first two ports are capable of establishing a ring topology.
Note
In order to use the ring topology, the GSDML file version V2.3 must be installed.
This file can be found, for example, on the memory card as
"\SIEMENS\SINAMICS\DATA\CFG\PNGSD.ZIP".
Configuring media redundancy
The ring topology is configured by appropriately configuring the participating devices
individually in STEP 7.
10.5.4 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.
SINAMICS DCM DC Converter
Operating Instructions, 02.2015, A5E34763375/RS-AA/001
ac.maher.co.ir
Descriptions of functions
10.5 Communication via PROFINET IO
475