[foxboro] Migration path for fault tolerant gateways with non-redundant cabling

Hi all,

I'm looking at migrating from existing AB Integrator 30s to Serial AB
FDSI modules in some plant areas.

Most of our existing gateways are configured as fault tolerant
gateways with non-redundant cabling.
The design philosophy behind this has been to provide fault tolerance
or redundancy at the DCS level, because multiple PLCs are normally
connected to our gateways, but not provide redundant cabling or PLC
port connections.  This has been a reasonable design, as we have not
experienced cabling faults, and while significant, KE or KFC failures
only affect a single PLC.  Where we have had DCS module failures the
fault tolerance has kept us from losing communications with groups of
PLCs.

I'm having trouble extending this philosophy to the FDSI modules.  I
realize that fault tolerance is provided at the CP270 level, but I
remain concerned that a single FBM230 FDSI module failure could cause
loss of communications with groups of PLCs.

When we use FDSI modules to replace AB30s to communicate with PLCs it
appears we have 2 choices:
1) Single FBM230 to our existing single cable path - single module
failure could comms with many PLCs.
2) Redundant FBM231s - requires redundant cabling and device connections.

Is there any way to have redundant FBM231s with non-redundant cabling?

Regards,

Kevin FitzGerrell
PT Freeport Indonesia
 
 
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