4.6 Profibus cabling guidelines
This section provides guidelines on possible ways to extend PGM redundancy to support Profibus media
redundancy. Note that these illustrations are provided for references purposes only. You must refer to vendor
documentation for actual design rules and placement/use of network components and terminators.
"Copper cable-based media redundancy" on page 29
"Fiber-optic cabling-based media redundancy" on page 30
"Redundant PGM in a non-redundant Profibus cabling" on page 30
4.6.1 Copper cable-based media redundancy
The following diagram illustrates the copper cable-based Profibus topology. In this topology, DP cable A and
DP cable B are the redundant backbone network. To this network, the switch slave supporting media
redundancy can be directly connected. This network can have non-redundant segment like the ones on the left
side of the diagram or DP Net-1 and DP Net-2 where redundant PGMs are connected through RLM modules.
Terminators are very important for copper segments. All Copper segments must use external terminator units.
4 PROFIBUS GATEWAY MODULE (PGM) INSTALLATION