Technical data

PROFIBUS Network Manual
System Manual, Edition 04/2009, C79000-G8976-C124-03
189
Passive components for optical networks
7
7.1 Fiber-optic cables
Fiber-optic cable
On fiber-optic cables (FOC) data is transmitted by modulating electromagnetic waves in the
range of visible and invisible light. The materials used are highquality plastic and glass
fibers.
This sections below describe only the fiberoptic cables from the SIMATIC NET range
intended for PROFIBUS. The various types of fiberoptic cable allow components to be
connected together in a way suitable for the operating and environmental conditions.
Compared with electrical cables, fiberoptic cables have the following advantages:
Benefits
● Galvanic isolation of stations and segments
● No equipotential bonding currents
● Transmission path immune to external noise
● No lightning protection required
● No noise radiation along the transmission path
● Low weight
● Depending on the fiber type, cables several kilometers long can be used even at higher
transmission rates.
● The transmission rate does not affect the maximum permitted cable length
● The meter markers printed on the cable make it easier to identify the length.
(Serve as orientation; accuracy ±5 %.)
Point-to-Point Connection
For technological reasons, only pointtopoint connections are possible with fiberoptic cables;
in other words, one transmitter is connected to one receiver. For duplex transmission
between two nodes, two fibers are therefore necessary (one for each transmission direction).
With the optical components for PROFIBUS, bus, star and ring structures can be
implemented.