31
Setting up a PROFIBUS Network
Section 2-5
2-5
Setting up a PROFIBUS Network
2-5-1
Network Structure
Communication Medium
The PROFIBUS standard defines the use of EIA RS-485 as the main commu-
nication transport medium. The PRT1-SCU11 is designed to interface directly
to this type of medium. This section will discuss the setup of networks based
on this medium.
Note The other communication medium specified for PROFIBUS is optical fibre.
The PRT1-SCU11 does not provide a direct interface to this type of medium.
However, by using third party couplers an interface between EIA RS-485 and
optical fibre networks can be made.
Linear Bus Topology
PROFIBUS DP defines the use of the Linear Bus Network Topology. The Bus
must be terminated at both ends, and must not contain network branches.
The total cable length of the bus depends on the cable and the selected baud
rate. Also, RS-485 specifies a maximum of up to 32 devices - master and
slave devices - per line segment. If more than 32 devices are to be connected,
or if the total length of the segment must be extended beyond its maximum,
repeaters must be used to link the separate segments.
Note Repeaters are devices which connect two segments. They do not have a
device address of their own, but they do count in the total number of devices
in a segment.
Repeaters
A maximum of up to three repeaters between two devices in a network can be
used, i.e. a network can consist of up to 4 segments. The maximum number
of PROFIBUS devices in such a network is then 122. The figure below shows
an example of a two-segment network.
Tree Topology
The use of repeaters allows the extension of three or more Linear Bus seg-
ments into a Tree topology. In a tree topology more than three repeaters are
allowed, provided that there are no more than three repeaters between any
Station 2
Station 3
Station 31
Repeater
Station 63
Station 33
Station 32
Termination
Termination
Termination
Termination
OMRON
SYSMAC CS1G
PROGRAMMABLE
CONTROLLER
Station 1
Summary of Contents for PROFIBUS DP GATEWAY
Page 1: ...OPERATION MANUAL PROFIBUS DP Gateway to Host Link Compoway F PRT1 SCU11 Cat No W01E EN 02 ...
Page 2: ...PRT1 SCU11 PROFIBUS DP Gateway Operation Manual Revised September 19 2005 ...
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