electromagnetic lock connects to NC of VTO (RS485 port 3) while its negative end
connects to COM of VTO (RS485 port 1).
When VTO connects to door sensor in electromagnetic lock, one end of door sensor
connects to ALM2 of VTO (RS485 port 6) while the end connects to GND of VTO
(RS485 port 4). See Figure 2- 14.
Figure 2- 14