Connecting A Fiber-Optic Cable To The Profibus Device; Permissible Cable Lengths On The Optical Profibus-Dp Network - Siemens S7-400 Installation Manual

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
SIMATIC NET
PROFIBUS
Fiber-Optic Cable
Plastic fiber-optic
duplex conductor
Plastic fiber-optic
standard cable
PCF fiber-optic
standard cable
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 t 50 m) and PCF fiber-optic cable for the connection
between the DP master and the first DP slave in the partyline topology (distance
u50 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.
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
Permissible Cable Lengths on the Optical PROFIBUS-DP Network (Partyline
Topology)
Maximum cable
Lengths Between Two
Projected for 1 Network
Nodes (in m)
50
50
300
Networking
(= 32 nodes) (in m)
1.550
1.550
9.300
5-31