ABB AC 800M, User Manual

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Basics of fibre optics topology technologies Section 2 Transmission Technology
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Redundant Optical Ring
The redundant optical ring structure represents a special form of line topology. A
high degree of network operating safety is achieved by ”closing“ the optical line. A
redundant optical ring can only be realized with modules supporting two optical
ports of the same type.
Monitoring mechanisms, to be set on the optical link modules:
• Send echo: yes
• Monitor echo: yes
• Suppress echo: yes
• Segmentation: yes
An interruption of one or both optical fibers between two modules is detected by the
optical link module and the ring is transformed into an optical line.
If one module fails only those terminals connected to this module or the RS485
segment are uncoupled from the ring. The remainder of the network itself continues
to function as a line.
Figure 12. Network structure in a redundant optical ring topology