LG Air Conditioning via PI-485 and LGAP protocol

TapHome supports direct communication via RS485 (BUS 1, BUS 2 or BUS 3 terminal) with LG air conditioning condensers and split units. This is done by LG PI-485 communication card and by proprietary LGAP communication protocol.

  • Communication via RS485 (Bus) connection.
  • Multiple split units can be fully operated from TapHome with minimum additional costs.

It is possible to control every split unit separately:

  • On / Off
  • Operation mode (Cooling, Dehumidification, Fan only, Auto, Heating)
  • Thermostat (Set point, Actual temperature)
  • Fan speed (Low, Medium, High, Auto)
  • Vane swing (On, Off)


LG AC product linePI-485 built inPI-485 can be added
Multi V 3

Multi FDX

Multi MU3 and higher
E.g.: MU3M25

Split 18 and higher

Multi MU2
E.g. MU2M15, MU2M16, MU2M17



Connect PI-485 card with outdoor condenser unit

  1. Disable power to System
  2. Connect CN_OUT on the PI‐485 to the CN_CENTRAL on the ODU PCB
  3. Connect BUS_A and BUS_B on the PI‐485 to the LG Central Controller or Gateway
  4. Select proper DIP Switch configuration:
    1 and 4 ON, all others OFF
  5. Connect CN_PWR on the PI‐485 to the Outdoor Unit PCB Power Connector
  6. Restore Power to the System

Make sure that PI-485 card is working properly:


LED blinks as many as the number of Connected Indoor units, and then turns OFF.

This process is repeated after every 3 minutes

Orange and Yellow LED

LED blinks continuously

Green RS485 LED

LED blinks when PI-485 receives data from central controller.

For more details, see LG PI-485 Installation Manual:

Connect PI-485 with TapHome

One or more PI-485 cards can be connected to TapHome BUS terminal. This communication line cannot be combined with TapHome Bus devices, or Modbus RTU devices.


Assigning addresses to LG split units

Turn on indoor split unit. To set its unique identification address (from 1 to 16), you will need to use combination of buttons on infrared remote controller.

Press and hold reset switch on infrared remote control. At the same time, hold left-top button and release reset switch. Please note, that second button differs on every model. If left-top button does not work, try to use MODE or FAN buttons. Once you enter address configuration mode, you can see 2 digits on the display and you can change address by pressing TEMPERATURE UP / DOWN buttons. Press reset on remote controller when you are done.

Defining LG interface in TapHome

Open Settings → Hardware → TapHome Bus → Terminals and disable one BUS terminal so that you can use it for communication with LG.

In Settings → Hardware → Add new interface → LGAC

Add split units with proper address.