Ring Topology; Redundant Optical Ring - Siemens SIMATIC NET Operating Instructions Manual

7.1.5

Ring topology

7.1.5.1

Redundant optical ring

This network topology is a special form of the bus topology. "Closing" the optical bus
achieves high operational reliability in the network. A redundant optical ring can only be
implemented using modules with two optical channels.
Figure 7-3 Network structure in a redundant optical ring topology
Monitoring mechanisms
● Send echo: yes
● Monitor echo: yes
● Suppress echo: yes
● Segmentation: yes
The interruption of one or both fiber-optic cables between the modules is detected by the
OLM and the ring becomes an optical bus.
If one module fails, only the end devices connected to this module or the RS-485 segment
are disconnected from the ring. The rest of the network itself remains functional as a bus.
Optical link module
Operating Instructions, 01/2020, C79000-G8976-C270-06
Planning/configuring
7.1 Network topologies
59