You are here: PRODUCTS / Locks / Control units / Door units Door units Instead of pulling the cable from the central to the product, you need to pull Aptus485 bus from the central to the door unit. Then, connect the door environment and its products (eg. Readers, entry phones and locks) to door units Koppla. Koppla 2100Apartment control unit for access control, energy meterin… Koppla 4300Door unit for access, booking, entry phone, alarm and ene…