LG PI-485 protocol

Supported device types and versions
Communication line configuration
Communication station configuration
I/O tag configuration
Literature
Document revisions

Supported device types and versions


The protocol supports reading and writing data with LG's proprietary serial (2-wire RS-485 bus) PI-485 protocol. This protocol is used by LG air conditioners and heat pumps for communication.

The protocol has been deployed to communicate with the LG Therma V heat pump (HU071MR U44).

Communication line configuration


Required line parameters:

Communication station configuration


  • Communication protocol: G PI-485
  • Station address – a number in the range from 0 to 63 (according to the configuration setting of the LG device) specified either as a decimal number or a hexadecimal number with a hash at the beginning (e.g. #1A).


Station protocol parameters

Configuration dialog box - tab „Parameters".
They influence some optional parameters of the protocol.

Table 2

Full nameMeaningUnitDefault value
Retry Count
A retry count of the request in case of a communication failure.-1
Retry Timeout
The delay between request retry in case of a communication failure.ms0 milliseconds
Wait First Timeout
The delay after sending the request before reading the response.ms100 milliseconds
Wait Timeout
The delay between response readings till its completing.ms100 milliseconds
Max Wait Retry
Retry count of response reading till its completing.-4

Passive Mode

Activating the passive mode. In this mode, no requests are sent, only messages read from the bus are processed.
The passive mode is used for reading data if there is another master on the bus (e.g. communication converter to Modbus protocol - LG PI485 Gateway).
YES/NONO

For further information on protocol parameters, see the topic Communication line - configuration dialog box.

I/O tag configuration


Possible I/O tag types: Ai, Ao, Ci, Co, Di, Dout, Qi

The address of the I/O tag is textual. The following table shows a list of existing addresses:

AddressI/O tag typeDescription
LOCK_REMOTEDout

Set the remote controller functionality: Lock (1) / Unlock (0).

LOCK_REMOTE_RDDi

Get the remote controller functionality: Lock (1) / Unlock (0).

OPERATE_OUTPUTDout

Set the device functionality: the device is stopped (0) / working (1).

OPERATE_OUTPUT_RDDi

Get the device functionality: the device is stopped (0) / working (1).

OPERATE_DHWDout

Set the domestic hot water heating in the built-in boiler: disabled (0) / enabled (1).

OPERATE_DHW_RDDi

Get the domestic hot water heating in the built-in boiler: disabled (0) / enabled (1).

OPERATE_MODEAo

Set the mode of operation: 0=cooling, 1=dehumidification, 2=ventilation, 3=auto, 4=heating.
Note: for a heat pump, modes 0, 3, 4 are relevant.

OPERATE_MODE_RDAi

Get the mode of operation: 0=cooling, 1=dehumidification, 2=ventilation, 3=auto, 4=heating.
Note: for a heat pump, modes 0, 3, 4 are relevant.

TEMP_OUTPUT_SPAo

Set the desired outlet water temperature.

TEMP_OUTPUT_RDAi

Get the desired outlet water temperature.

TEMP_DHW_SPAo

Set the desired temperature of the domestic water in the built-in boiler.

TEMP_DHW_RDAi

Get the desired temperature of the domestic water in the built-in boiler.

TEMP_WATER_INAiCurrent inlet water temperature.
TEMP_WATER_OUTAiCurrent outlet water temperature.
TEMP_ROOMAi

Current room temperature (external sensor connectable to the indoor heat pump unit).

TEMP_TANKAiThe current temperature of the domestic water in the built-in boiler.
TEMP_SOLARAiThe current temperature of an optional external solar system (if connected).
CONNECTED_IDUDiThe indoor unit is connected (1) or disconnected (0).
TGT_TEMP_SELDi

The current setpoint is the temperature of air TEMP_ROOM (0) or water TEMP_OUTPUT_SP (1).

Note: Temperatures are integer numbers (°C).

Note: it takes longer to set the values (approx. 12 seconds).
Example: TEMP_OUTPUT_SP has a value of 40 °C. After writing a value of 42, only after approx. 12 seconds does the value of the I/O tag TEMP_OUTPUT_RD change to 42.

Literature


Changes and modifications


  • February 2008 – Option Checksum.
  • August 2009 - Support of the value DOUT.

Document revisions


  • Ver. 1.0 – September 2021 – Protocol implementation

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