Networking
5-28 AutomationSystem S7-400 Hardwareand 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.
Table5-7 Permissible CableLengths onthe Optical PROFIBUS-DP Network (Partyline
Topology)
SIMATICNET
PROFIBUS
Fiber-OpticCable
Maximum cable
LengthsBetween 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

Togain 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

Youcan order PCF fiber-optic cables fitted with 2x2 connectors in specific lengths
from Siemens.
Lengths and order numbers: See Table5-5

Laying Plastic Fiber-Optic Cable

Youcan 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.