Redundancy for a databus transmission
This is a very broad topic, known as "fault tree analysis" &mdash; probably too broad to address here in our Q and A format.

The question about your serial bus needs to be evaluated in the context of the larger system. You need to consider what kinds of faults are likely and the cost to mitigate each kind of fault. You need to consider both electrical faults within the master and slave devices themselves, as well as physical faults with the wiring and connectors.

Sometimes redundancy is the right answer; other times, having a subsystem make a transition to a "safe state" (until repairs can be made) when a fault is detected is sufficient.