Siemens SIMATIC NET PROFIBUS manual Fiber-Optic Cables, Fiber-Optic Cable FO

Passive Components for Electrical Networks

7.1Fiber-Optic Cables

Fiber-Optic Cable (FO)

On fiber-optic cables (FO) data is transmitted by modulating electromagnetic waves in the range of visible and invisible light. The materials used are high-quality plastic and glass fibers.

This chapter describes only the fiber-optic cables from the SIMATIC NET range intended for PROFIBUS. The various types of fiber-optic cable allow components to be connected together in a way suitable for the operating and environmental conditions.

Compared with electrical cables, fiber-optic cables have the following advantages:

Advantages

SElectrical isolation of nodes and segments

SNo potential equalization currents

STransmission path immune to external noise

SNo lightning protection required

SNo noise emission along the transmission path

SLight weight

SDepending on the fiber type, cables several kilometers long can be used even at higher transmission rates.

SThe transmission rate does not affect the maximum permitted cable length

Point-to-Point Link

For technological reasons, only point-to-point connections are possible with fiber-optic 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.

7-2	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000