Hello,

Please forgive my ignorance if the solution to my problem is blatantly obvious. My goal is to integrate my Actron air A/C unit into my home assistant system. I could fork out the $1k odd for the wifi connect module but upon inspection of my indoor unit i found an RS485 port. I did a little research and found that they sell a BMS board which allows for modbus communication. It has a data connection from this RS485 port i mentioned and has a modbus BMS IN and OUT port.

This got me thinking, is it as easy as connecting into this onboard RS485 port coupled with a USB converter and start polling the modbus? Anyway ive tried and failed. I cant get my head around whether i actually need this BMS card or not. What else aside from assigning a slave ID and port settings could this card be used for? I was hoping of implementing an ESP8266 to locally poll the modbus and then wirelessly transmit to my HA.

What am i missing here?

Thanks for any help, even a steer in the right direction would be greatly appreciated.

 

The onboard RS-485 port likely uses a proprietary protocol. The BMS board is a gateway device that translates between Modbus RTU and the proprietary protocol. Most likely, you'll need the BMS card to communicate to your A/C unit.

 

The onboard RS-485 port likely uses a proprietary protocol. The BMS board is a gateway device that translates between Modbus RTU and the proprietary protocol. Most likely, you'll need the BMS card to communicate to your A/C unit.

I was afraid of that. Ok perhaps there’s a way to decipher this protocol.