Siemens SIMATIC NET PROFIBUS User Manual

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PROFIBUS Networks SIMATIC NET

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

The optical transmission technique complies with the PROFIBUS User
Organization guideline:
“Fiber Optic Data Transfer for PROFIBUS” /3/.

The optical version of SIMATIC NET PROFIBUS is implemented with integrated,
optical ports, optical bus terminals (OBT) and optical link modules (OLM).

Duplex fiber-optic cables are used as the medium made of glass, PCF or plastic
fibers. Duplex fiber-optic cables consist of two conducting fibers surrounded by a
common jacket to form a cable.

Modules with integrated optical ports and optical bus terminals (OBTs) can be
interconnected to form optical networks only with a bus structure.

Using OLMs, optical networks can be installed using a bus, star and ring structure.
The ring structure provides a redundant signal transmission path and represents
the basis for networks with high availability.

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Regardless of the transmission rate, large distances can be covered between
two DTEs
(connections between OLM and OLM up to 15,000 m)

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Electrical isolation between nodes and transmission medium

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When plant components at different ground potential are connected, there are
no shield currents

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No electromagnetic interference

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No additional lightning protection elements are required

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Simple laying of fiber-optic cables

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High availability of the LAN due to the use of a ring topology

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Extremely simple attachment technique using plastic fiber-optic cables over
shorter distances.