I can really only speak towards what my company calls an intelligent MCC.
Each starter or distribution unit has its own microprocessor controller located inside the withdrawable starter module. This microprocessor provides all the motor protection, gathers what ever information (voltage, current...) is required by the larger control scheme and can respond to commands given to it by the next level up (HMI, the DCS). Information moves in either direction along an internal bus for the MCC system. Commands and data retrival can be accomplished either through a HMI (located in the either the MCC or some other location) or via the next level of the overall DCS.
