Siemens ESM - Manual (Page 35)

Network Topologies with OSM/ESM
Industrial Ethernet OSM/ESM
C79000-Z8976-C068-10
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3.2 Redundant Ring Structure
With the aid of an OSM functioning as the redundancy manager (RM), both ends
of an optical bus made up of OSMs can be closed to form a redundant optical ring.
The OSMs are connected together using ports 7 and 8.
The RM monitors the OSM bus connected to it, closes the bus if it detects and
interruption and therefore reestablishes a functioning bus configuration. A
maximum of 50 OSMs are permitted in an optical ring. This allows reconfiguration
time of less than 0.3 s to be achieved. The RM mode is activated on the OSM
using a DIP switch (Section 4.2.4.1).
OSM in
RM mode
OSM ITP 62 OSM ITP 62 OSM TP 62 OSM TP 62
OSM ITP 62
OSM ITP 62 OSM ITP 62 OSM ITP 62
1
1 1 1 1
1
1 1 1
1
1 Fiber-optic cable (FOC)
OSM ITP 53
Figure 12: Redundant Ring Structure with OSMs
A redundant electrical ring can be established using ESMs in the same way. To
achieve this the ESMs must be connected together using ports 7 and 8. One
device must be switched to the redundancy manager mode. With ESMs and a
maximum of 50 devices in the ring, a reconfiguration time of less than 0.3 s can
also be achieved.