I need to convert a single PM891 into a redundant PM891 system with BC810K02 set and CI854 pairs
In short, it says that with PM891 Redundancy, the Redundancy Link consists of two cables – RCU Data Link Cable (TK855) and RCU Control Link Cable (TK856). Additionally, in a redundant system, the two controllers are linked together with both the RCU Link Cables. Both the processor units are also connected to the same CEX-Bus, using either the TK850 CEX-Bus extension cable or through BC 810, therefore allowing any one of the two units to control the expansion units. Additionally, as with the redundancy of the other controllers, the S800 I/O modules are connected to the two processor units with the optical ModuleBus and two TB840s.
Here is the link to the manual.
I hope that this is of help.
AFAIK, there is no configuration drawing showing the redundant configuration of PM981, BC810 and CI854, all together. But the configuration is the same as that of redundant PM864 or PM866.
For both primary and backup PM891, BC810 should be connected to the left of the controller; and CEX unit CI854 should be connected to the left of BC810.
The image (PM891 Redundant) which you have attached is basically correct.
-> BC810 does not have any hardware address to be assigned in Control Builder M.
-> TK850 cable connection is not required if BC810 is used.
-> PM891 needs RCU Data Link and RCU Control Link, which is not the case for PM864 or PM866.
Please refer AC 800M 6.0 Controller Hardware manual (3BSE036351-600) for your reference. After configuring, you can also refer 'Verification of Redundant CPU' section from this manual.
Hope this helps.