Siemens SIMATIC NET System Manual page 80

Network structures and network configuration
2.2 Network structures
Example: Structure of a redundant network with SCALANCE X switches
With the aid of a redundancy manager (RM), the two ends of a bus can be closed to form a
redundant ring. All the media converters SCALANCE X100/200/300/400 and X500 devices
can be used in this ring. The role of the RM can be handled by the SCALANCE
X200/X300/400 and X500 devices.
The RM monitors the line connected to it, if there is an interruption, it closes the ring and
restores a functioning bus configuration. A maximum of 50 of the SCALANCE X devices
mentioned above are permitted in an optical ring. Here, a reconfiguration time of less than
0.3 seconds is achieved. The RM mode on the SCALANCE X devices is configured in the
software. The maximum length of the fiber-optic cable between two devices is 3 000 m for
multimode fiber and 200 km for single-mode fiber. This means that a maximum of 150 km
(multimode) can be achieved for the entire optical ring consisting of 50 switches.
Figure 2-6 SCALANCE X: Redundant setup of an automation network
See also
Network topologies (Page 75)
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System Manual, 09/2019, C79000-G8976-C242-10
Industrial Ethernet