Based on the analysis of the Commax DP-RA01 installation manual, the following observations and recommendations are made:
On the rear PCB of the DP-RA01, you’ll find a small bank of DIP switches (usually 4 positions). These set the for apartment buildings. commax dp-ra01 installation manual
This guide assumes you have already run a 4-conductor wire from the door station to the indoor monitor location. Based on the analysis of the Commax DP-RA01