Profibus DP Mk2 Option Card Installation Manual
24 of 84 Publication PUB088-005-00_1017
4.4 Redundant Systems – RedCom Redundancy
The RedCom Dual Channel Profibus DP (Mk2) Option Card version has two redundant
communications channels. Like the Simple card, the RedCom card supports two types of redundant
operation and the details are as described in Profibus Guideline 2.212 ‘Specification Slave
redundancy’. The two modes are:
SR – System Redundancy (One common slave address)
FR – Flying Redundancy (Two slave addresses offset by 64)
As with the Simple Redundant card, there are two basic considerations when looking at redundant
systems; protection against the failure of the connecting cable and protection against failure of the
device. Most systems consider cable protection to be the most important and this is termed ‘SR’ or
System Redundancy. The alternative setup, using only a single cable, but with two Profibus
connections is termed ‘FR’ or Flying Redundancy. With FR systems there are two Profibus interfaces
on the slave, but only one slave, so protection against failure of the Profibus interface is included. SR
and FR are described in more detail in the previous section.
The Profibus DP (Mk2) RedCom Dual Channel card includes:
Two Profibus Connections, Channel 1 and Channel 2
RedCom link between the two connections
Redundancy extensions to the V1 protocol
No loss of data during switching
Selectable FR/SR mode
Status reported in Extended Diagnostics data
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