Star Topology - Siemens SIMATIC NET OLM12M Description And Operating Manual

6ZB5530–3AB00–0BA0/01
4.2

Star Topology

Several SIMATIC NET OLM12M optical link modules are connected together to form an active
PROFIBUS star coupler. Further SIMATIC NET OLM12M optical link modules are connected to
these OLMs via FO cable. The SIMATIC NET OLM12M optical link modules of the star coupler are
interconnected via the electrical channels.
Mode settings: L=Line, I=Inactive
Figure 3: Network Structure of an Optical Star Topology
All the optical channels connected to the star structure are switched to the 'Line' mode.
Unconnected optical channels must be set to the 'Inactive' mode.
The monitoring function allows the FO cable to be monitored by both connected SIMATIC NET
OLM12M optical link modules. Even if only one transmission direction fails, the segmentation
function associated with the monitoring ensures that the entire connection is separated from the
network. In the star topology, this means that only the DTE on the disturbed path is separated from
the network, problem-free operation continues in the remaining network.
Copyright Siemens AG 1997
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SIMATIC NET OLM12M