Protocol Error? UHXM55MA0

[aususer]

Hello Team!
Loving this project and while I had some troubles getting it to communicate with my LG UHXM55MA0 (ducted airconditioner), but eventually managed to get it working with a LIN-Bus transceiver I bought on ebay (https://ebay.us/m/ROUOAI).
I've now successfully made it communicate..

.but.

when I look at the logs that come out of the received data, I think there is some kind of protocol/framing problem.

[10:03:55.764][I][app:206]: ESPHome version 2026.1.3 compiled on 2026-02-01 11:44:09 +1100
[10:03:55.764][I][app:213]: ESP32 Chip: ESP32-C3 r0.3, 1 core(s)
[10:03:55.764][C][logger:316]: Logger:
[10:03:55.764][C][logger:316]: Max Level: DEBUG
[10:03:55.764][C][logger:316]: Initial Level: DEBUG
[10:03:55.765][C][logger:322]: Log Baud Rate: 115200
[10:03:55.765][C][logger:322]: Hardware UART: USB_SERIAL_JTAG
[10:03:55.765][C][logger:332]: Task Log Buffer Size: 768 bytes
[10:03:55.765][C][uart.idf:238]: UART Bus 0:
[10:03:55.766][C][uart.idf:152]: TX Pin: GPIO21
[10:03:55.766][C][uart.idf:152]: RX Pin: GPIO20
[10:03:55.766][C][uart.idf:243]: RX Buffer Size: 256
[10:03:55.766][C][uart.idf:243]: RX Full Threshold: 1
[10:03:55.766][C][uart.idf:243]: RX Timeout: 2
[10:04:00.076][C][uart.idf:249]: Baud Rate: 104 baud
[10:04:00.076][C][uart.idf:249]: Data Bits: 8
[10:04:00.076][C][uart.idf:249]: Parity: NONE
[10:04:00.076][C][uart.idf:249]: Stop bits: 1
...
...
[10:05:05.766][D][lg-controller:1360]: update
[10:05:05.789][D][lg-controller:954]: received 00.13.24.00.A2.8C.00.14.00.00.00.41.00 (13)
[10:05:05.789][E][lg-controller:964]: invalid checksum 00.13.24.00.A2.8C.00.14.00.00.00.41.00 (13)
[10:05:05.811][D][lg-controller:954]: received 13.24.00.A2.8C.00.14.00.00.00.41.00.13 (13)
[10:05:05.811][E][lg-controller:964]: invalid checksum 13.24.00.A2.8C.00.14.00.00.00.41.00.13 (13)
[10:05:11.771][D][lg-controller:1360]: update
...
[repeated]

It looks that the code isrepeated over and appears that the packet of data recieved is two characters shorter than the previous.
Im not a programmer (im a hardware guy).. but it looks like a framing problem to me.

Anyone have any idea whats going on?
Is it that this aircon uses a different protocol to this code setup?

ps. dont have any zones etc.. s half the options would be useless to me.
Any input appreciated.
Cheers.

Mike
Melbourne, Australia.

[JanM321]

Two issues I can think of: either it's a problem with the hardware (I don't know if it's actually compatible with this project?) or your unit uses the older AC protocol (see #79 for example). Does your unit support the PREMTB100 controller?

[aususer]

Thanks for this suggestion.. Considering that I'm getting ANY data says that the comms appears to be working so I'm thinking this is MORE a protocol problem (as you suggested and highlighted in your link).

I tried to build it but its old and wouldn't build.. Flameeyes/esphome-lg-pqrcuds0#2

I'll wait and see if anyone has a way to build it... im no programmer.