The second floor will be on its own home run? If so connect Data A, Data B and NEG from the M1 to the M1DBH. Connect the the +12V and NEG Output from the P212S to the +12V and NEG on the M1DBH. The P212S requires its own TRG1640 Transformer and battery backup. When using the M1DBH and you want to connect M1DBHs together you can connect from the “First” Unused Port of the first M1DBH to J1 on the second M1DBH using a crossover cable. See the M1DBH for additional instructions on how to make the crossover cable. The “ONLY” time you can cut the JP1 Jumper to omit power to the next M1DBH is if all 9 ports on the first M1DBH are used. If not able to fill all 9 port then simple do not connect the “Brown” wire in the Crossover cable.