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 line category: Serial, SerialOverUDP Device Redundant.
- Transfer parameters: baud rate 4800, 8 data bits, 1 stop bit, parity NONE.
- Other parameters see the Communication line - configuration dialog box.
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 name | Meaning | Unit | Default 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. | ms | 0 milliseconds |
Wait First Timeout | The delay after sending the request before reading the response. | ms | 100 milliseconds |
Wait Timeout | The delay between response readings till its completing. | ms | 100 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/NO | NO |
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:
| Address | I/O tag type | Description |
|---|---|---|
| LOCK_REMOTE | Di, Dout | Get/set the remote controller functionality: Lock (1) / Unlock (0). |
| OPERATE_OUTPUT | Di, Dout | Get/set the device functionality: the device is stopped (0) / working (1). |
| OPERATE_DHW | Di, Dout | Get/set the domestic hot water heating in the built-in boiler: disabled (0) / enabled (1). |
| OPERATE_MODE | Ai, Ao | Get/set the mode of operation: 0=cooling, 1=dehumidification, 2=ventilation, 3=auto, 4=heating. |
| TEMP_OUTPUT_SP | Ai, Ao | Get/set the desired outlet water temperature. |
| TEMP_DHW_SP | Ai, Ao | Get/set the desired temperature of the domestic water in the built-in boiler. |
| TEMP_WATER_IN | Ai | Current inlet water temperature. |
| TEMP_WATER_OUT | Ai | Current outlet water temperature. |
| TEMP_ROOM | Ai | Current room temperature (external sensor connectable to the indoor heat pump unit). |
| TEMP_TANK | Ai | The current temperature of the domestic water in the built-in boiler. |
| TEMP_SOLAR | Ai | The current temperature of an optional external solar system (if connected). |
| CONNECTED_IDU | Di | The indoor unit is connected (1) or disconnected (0). |
| TGT_TEMP_SEL | Di | 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, a reading follows which changes the value back to 40. Only after approx. 12 seconds does the value of the I/O tag 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
Related pages: