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Siemens Automation System S7-400 User Manual

Page 126

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Networking

5-28

Automation System S7-400 Hardware and Installation

A5E00850741-01

5.8.3

Connecting a Fiber-Optic Cable to the PROFIBUS Device

Cable Lengths

With fiber-optic cables, the length of the cable segment does not depend on the

transmission rate.
Each bus node in the optical PROFIBUS-DP network has repeater functionality.

The distances specified below are the distances between two neighboring

PROFIBUS nodes in the partyline topology.
The maximum cable length between two PROFIBUS nodes depends on the type of

the fiber-optic cable used.

Table 5-7

Permissible Cable Lengths on the Optical PROFIBUS-DP Network (Partyline

Topology)

SIMATIC NET

PROFIBUS

Fiber-Optic Cable

Maximum cable

Lengths Between Two

Nodes (in m)

Projected for 1 Network

(= 32 nodes) (in m)

Plastic fiber-optic

duplex conductor

50

1.550

Plastic fiber-optic

standard cable

50

1.550

PCF fiber-optic

standard cable

300

9.300

Mixed Use of Plastic Fiber-Optic and PCF Fiber-Optic Cable

To gain the maximum benefit from the different cable lengths you can mix the

plastic and PCF fiber-optic cables.
For example, you can use plastic fiber-optic cable for connections between DP

slaves locally (distances <50 m) and PCF fiber-optic cable for the connection

between the DP master and the first DP slave in the partyline topology (distance
>50 m).

Laying PCF Fiber-Optic Cable

You can order PCF fiber-optic cables fitted with 2x2 connectors in specific lengths

from Siemens.
Lengths and order numbers: See Table 5-5

Laying Plastic Fiber-Optic Cable

You can easily fit connectors to and install plastic fiber-optic cables yourself. Please

read the following information on how to do this and on the rules for laying the

cable.