The left Glareshield and center-left Main Instrument Panel (MIP) flood light is powered by the DC Essential Bus. The right Glareshield and center-right MIP flood light is powered by DC1 Norm Bus.
A simplified schematic of the pinouts with a relay connected to control correct behaviour:
When battery 1 and 2 are operating, essential bus services such as the captain side flood lighting and left MIP flood lighting will be available. With external power or with the APU turned on FO side flood lighting and right MIP flood is available.
Related schematic – Pedestal Flood Light Control
Unfortunately at the time of this writing, avionic software ProSimA320 does not provide native software gates to implement relay control to seperate the different Buses. Bus control can be implemented with ProSim using SimStack and the TCP/IP generic element output. Jeehell FMGS allows access to these gates using the API (facilitated by the Cockpit Concept relay board).