Siemens SIMATIC NET PROFIBUS How a Fiber-Optic Cable Transmission System Works, Introduction

Configuring Networks

3.2.1How a Fiber-Optic Cable Transmission System Works

Introduction

This section describes the structure and functions of an optical transmission system. The information here will help you to understand the rules for calculating the optical power budget in the next section.

Transmission Path

An optical transmission path consists of a transmitter, the optical fiber, and a receiver.

Power supply

Signal	E / O
converter	converter

Electr. signal (digital/analog)

Optical fiber

Attenuation transmission path

E/O = Electro-optical converter

O/E = Optoelectrical converter

Power supply

O / E	Signal
converter	converter

Electr. signal (digital/analog)

Figure 3-2 Structure of a Link

Transmitter

The transmitter in an optical digital transmission system consists of a signal converter that converts the digital signals from the electronics in to a pulse type suitable for the electro-optical converter, and an electro-optical converter (E/O converter) that converts the electric pulses to optical signals. In SIMATIC NET PROFIBUS, LEDs (LED = Light Emitting Diode) are used as E/O converters. The LEDs are specially adapted to the various transmission media.

Transmission Media

The transmission media used in SIMATIC NET PROFIBUS are as follows:

SPlastic fiber-optic cables

SPCF fiber-optic cables (polymer cladded fiber)

SGlass fiber-optic cables

For more detailed information about the various fiber-optic cables for SIMATIC NET PROFIBUS, refer to Chapter 7.

3-12	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000