4.3 Redundant Systems – Simple Redundancy
The Simple Dual Channel Profibus DP (Mk2) Option Card version has two redundant communications
channels. Like the RedCom version, this card supports two types of redundant operation.
SR – System Redundancy (One common slave address)
FR – Flying Redundancy (Two slave addresses offset by 64)
These two connection options allow for redundancy protection against either a failure of the highway
(SR mode) or failure of the card interface channel (FR mode). Most dual channel systems use two
highways and one connection to each, so the most common use for this card is in SR mode. The
functionality and provisions of the card are identical to the RedCom version except in the way the card
reports its status on the highway.
There are a number of PLC systems, including older PLCs, that do not have the ability to use the
RedCom system and as a consequence they are likely to report errors when connect to a RedCom
compliant card. If the PLC does not support the RedCom standard then the Simple Redundant card
must be used.
The Profibus DP (Mk2) Simple Dual Channel card includes:
Two Profibus Connections, Channel 1 and Channel 2
Selectable FR/SR mode
No Extended Diagnostics
A Simple Dual Channel card can be altered to a RedCom Dual Channel card, or vice versa, by
entering the appropriate value in parameter 15 in the GSD file.
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