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Monitoring fo links, Mixed structure, Redundant optical rings using olms – Siemens SIMATIC NET PROFIBUS User Manual

Page 36

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Topologies of SIMATIC NET PROFIBUS Networks

2-10

PROFIBUS Networks SIMATIC NET

6GK1970-5CA20-0AA1 Release 2 05/2000

Monitoring FO Links

Using the echo function, the connected OLMs can monitor the fiber-optic sections.
A break on a link is indicated by a display LED and by the signaling contact
responding.

Even if only one transmission direction is lost, the segmentation triggered by the
monitoring function leads to safe disconnection of the OLM from the star coupler.
The remaining network can continue to work without problems.

Mixed Structure

The star coupler can be made up with combinations of OLM/P, OLM/G and
OLM/G-1300 modules and at the RS-485 end with all types.

Redundant Optical Rings using OLMs

Redundant optical rings are a special form of bus topology. By closing the optical
bus to form a ring, a high degree of operational reliability is achieved

Path 1

S7-400

PG

S7-400

OP 25

Path 2

À

Terminating resistor activated

А

А

А

А

ET 200M

1 FO cable

2 LAN cable for PROFIBUS

4

2

4

3

À

1

1

1

1

3 PROFIBUS 830-1T connecting cable

4 PROFIBUS 830-2 connecting cable

А

А

Figure 2-5

Network Structure in a Redundant, Optical, Two-Fiber Ring Topology