opening up for cn_link

[rrelande]

congrats for a fantastic project!

I've started to reverse engineer CN_LINK, which is the protocol used by LG's own WiFI dongle.
it seems similar to CN_REMOTE but it is totally different. CN_link is a standard serial protocol with 4 wires
RX TX power and GND.

just sharing as there could be people interested for using CN_LINK.
My guess is that a LG unit will either have CN-LINK or CN_REMO,
sometimes both.

the new repository, which is a very draft so far is available here
https://github.com/rrelande/LGE-Serial-protocol/blob/main/README.md

I hope this helps people get started and hopefully we will be able to find out all details of the CN_LINK as well.

[JanM321]

Very interesting to see this!

Unfortunately the CN_REMO protocol I reverse engineered doesn't support all features of the indoor units (some settings require the WiFi dongle or IR remote) so an ESPHome implementation for CN_LINK would be useful.

[rrelande]

Thanks,
indeed this is quite promising as the number of LG devices is quite large.
the features available on CN-LINK are very promising as it goes beyond the scope of a wired remote.

The road leading to a ESP-HOME implementation starts with further reverse engineering of the protocol,
I hope that the initial exploration will help other fellow users contribute with their findings.
then a ESP-Home library or sw could be possible

[richardc1983]

How are you getting on with this?

[rrelande]

Thanks for checking, so far SW is able to find out the most important running parameters of the AC (operations, setpoint, current temperature) and adjust accordingly. The protocol is not straightforward, despite only understanding a fraction of the discussion, it's still a relief to be able to tap into the commands.

The SW is not in the situation that it can be released nor does it support open systems like HA or ESPhome. But it's able to replicate the commands and test PDUs which helps pave the way into understanding the protocol deeper.

[richardc1983]

I admire the time you people put into the reverse engineering.

[rrelande]

Thanks Richard, I admire what you have done for the wired controller decoding. The reverse engineering is indeed the most time consuming and difficult part of the project. Probably the most time consuming and confusing part is getting started in understanding the basic architecture, communication principles and PDU structure. A point that probably makes it even more difficult is that this dongle is used in dishwashers, kitchen hoods and so many other LG equipments and not only for HVAC.

This is the whole reason for sharing as much as possible of the findings so far and making it easier for the rest of the community to further develop the understanding of the protocol.

[maciejsszmigiero]

@rrelande the serial protocol that LG RAC WiFi "modem" uses is basically the same as what modem wraps in MQTT packets that it then transmits to a ThinQ cloud server.

Look at the UART framing format and RAC_056905_WW appliance description at the rethink project.

Looking at the actual RAC_056905_WW rethink handler code can also be helpful since these Wiki pages are not yet updated with recent developments.