Double Decks Bus, Super long Bus, BRT, MTR with 3 doors.
3 Doors Mode
Each units of counter only support 2PCS of binocular cameras for 2 doors, so over 2 doors, you must use 2 Units of BPC with 3 binocular cameras to monitor 3 doors. In multi-door mode, Unit A will collect Unit B datas, count all 3 doors data and send all of them to server by 3G.
Because two units has different requirements, so counter A must connect 3G network and GPS device, or connect 3G Mobile DVR or GPS Tracker, Counter B doesn't need 3G or GPS function.