Siemens SCALANCE X-200 Operating Instructions Manual page 251

These settings are described below.
Note
Prioritized startup
If you configure MRP in a ring, you cannot use the "prioritized startup" function in PROFINET
applications on the devices involved.
If you want to use the "prioritized startup" function, then disable MRP in the configuration.
In the STEP 7 configuration, properties dialog of the PROFINET interface > "Media
redundancy" tab > "MRP configuration" box, set the role to "Not node in the ring".
Domain
All devices configured in a ring with MRP must belong to the same redundancy domain. A
device cannot belong to more than one redundancy domain.
If you leave the setting for "Domain" as the factory set "default-mrpdomain", the factory
settings for "Role" and "Ring ports" also remain active.
The MRP settings remain in effect following a restart of the device or following a power down
and hot restart.
Role
NOTICE
If you reset to the factory settings, the MRP role of the device is also reset. If you are
operating a non-Siemens device as the redundancy manager in the ring, this may cause
loss of the data traffic.
The choice of role depends on the following use cases.
SCALANCE X-200
Operating Instructions, 12/2011, A5E00349864-19
PROFINET IO functionality
8.2 Settings in HW Config
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