7.6 PROFIBUS installation guidelines
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A PROFIBUS DP network may only be built up in linear structure.
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PROFIBUS DP consists of minimum one segment with at least one master and one
slave.
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A master has always been deployed together with a CPU.
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PROFIBUS supports max. 126 participants.
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Per segment a max. of 32 participants is permitted.
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The max. segment length depends on the transfer rate:
9.6 ... 187.5bit/s
®
1000m
500kbit/s
®
400m
1.5Mbit/s
®
200m
3 ... 12Mbit/s
®
100m
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Max. 10 segments may be built up. The segments are connected via repeaters. Every
repeater counts for one participant.
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The bus respectively a segment is to be terminated at both ends.
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All participants are communicating with the same transfer rate. The slaves adjust
themselves automatically on the transfer rate.
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As transfer medium PROFIBUS uses an isolated twisted-pair cable based upon the
RS485 interface.
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The RS485 interface is working with voltage differences. Though it is less irritable
from influences than a voltage or a current interface. You are able to configure the
network as well linear as in a tree structure.
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Max. 32 participants per segment are permitted. Within a segment the members are
linear connected. The segments are connected via repeaters. The maximum segment
length depends on the transfer rate.
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PROFIBUS DP uses a transfer rate between 9.6kbit/s and 12Mbit/s, the slaves are
following automatically. All participants are communicating with the same transfer
rate.
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The bus structure under RS485 allows an easy connection res. disconnection of sta-
tions as well as starting the system step by step. Later expansions don’t have any
influence on stations that are already integrated. The system realizes automatically if
one partner had a fail down or is new in the network.
The following picture illustrates the terminating resistors of the respective start and end
station.
PROFIBUS in general
Transfer medium
Bus connection
System 300S
+
Deployment PROFIBUS communication
PROFIBUS installation guidelines
HB140 | CPU | 315-4PN23 | en | 18-02
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