Siemens SIMATIC NET PROFIBUS manual Transmission Techniques for Optical Components

PROFIBUS NETWORKS

1.2.5Transmission Techniques for Optical Components

PROFIBUS User Organization Guideline

The optical transmission technique complies with the PROFIBUS User Organization guideline:

“Fiber Optic Data Transfer for PROFIBUS” /3/.

Integrated Optical Interfaces, OBT, OLM

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.

Advantages:

SRegardless of the transmission rate, large distances can be covered between two DTEs

(connections between OLM and OLM up to 15,000 m)

SElectrical isolation between nodes and transmission medium

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

SNo electromagnetic interference

SNo additional lightning protection elements are required

SSimple laying of fiber-optic cables

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

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

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