Ariston Nuos Evo+ Serial Communication

New user here, I hope I’m the right section.
I have two water boilers (Ariston NUOS Evo+) which unfortunately don’t come with a wifi module and apparently don’t support connection to a bus like newer models.
However, they do come with a serial port which I assume it’s for service.
My goal is to monitor the temperatures without stepping out outside in the garden every time, since they are installed outdoor. Eventually, that would be done in HA but for now even establishing proper communication would be a victory.
I tried to connect in the attempt to reverse engineer the protocol, tried RS232 initially but didn’t get any response. I switched to RS485 which apparently is returning data (not meaningful at the moment).
I was wondering if anyone managed to talk with this device before I try to reinvent the wheel, this looks like a proprietary protocol so I’m not even sure I will ever be able to succeed :slight_smile:


Hi Ric, i recently got a 2011 Nuos 250 and am also currently investigating informations about this port. According to the Documentation i could find online your Nuos also seems to have some kind of RJ12 like Serial Port.
But information seems to be very rare to this port. I also willing to spent some time reverse engeneering, maybe you could share what you got so far and could join foces

So my first Overview after disassemby of the Electrical Part:
Model:Ariston NUOS 250 SYS EXT,
Built: April 2011

The PCB has some Stickers with "Janus2 01.02.04 MAIN 000342405700 " Marking
The Mainprocessor is a Renesas R8C/27 IC


Tracking down the Traces of the “Serial Connector” RJ12/6P6C i got the following Pinout: Attention There may be much more SMD Part connected that i did not trace.

RJ12 /6P6C Pin ==> R8C IC Pin
1:TXD0 Pin17 (+100Ohm)
2:RXD0 Pin16 (+100Ohm)
3: VCC Pin7 (5V)
4:GND Pin5 (Vss/AVss)
5: MODE Pin8
6: RESET Pin3 (+ 1kOhm)

So the Connector is more or less directly connected to the IC Pins, so be aware of (Over)voltages or you will destroy your Mainboard. Do NEVER connect directly to Computer Serial Port RS232 unless you know what you are doing! I think at least a Level Converter needs to be used.It seems the main use is really to conencet a dedicated Flashing Device

As i had my Nuos already disassembled, i had some more looks on the PCBs and did some schematics.
There are 2 PCBs, one “Main” board and one “HMI” board with the Display and Knobs. Boards seem to communicate with a Serial Protocol @5V, and with 9600baud 8N1.At least you see reasonable and cyclically repeating ASCII Codes/Numbers. But It is also not very meaningful for me currently.
Here is some example of recurring data, if someone can give hints, i will appreciate:

The Lines so not seem to be ended by a Linefeed, but instead seem to start or end with “0xE2 0x96 0x92 0xE2 0x96 0x92”.

With RS485 if it is random garbage without any repetions, it might be a problem as RS485 is working differential and maybe only some noise on the Lines that are not meant for differential signals migth create random readings. I would be interested to see you data.

The accessable “Serial Port” only shows about 7 spikes on the TXD when you physically! connect your unit to power. After that the wires seemed to be constantly at 5V high. I guesss this is some sync signal for the Probe/Debugger in order to start communication. In order to see these Spikes on the Oszi it was necessary to have a pulldown resistor connected, otherwise it was constantly on High 5V

Sorry i am not allowed to reply by the ?!

Interesting read, maybe this is how to get the official RJ12 Serial interface of my NUOS 250 talking. But i was quite sucessfull at decoding the MainBoard <->HMI Communication as documented here in german sorry :slight_smile:

Googletranslate: Brauchwasserwärmepumpe Ariston Nuos 100/Schnittstelle -

I found this and maybe could be useful:

It seems that the boiler uses EBUS protocol and there exists a project that makes it possible to interface with HA:

I’m still investigating but it looks promising.

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I’m also interested, because I have a Nuos EVO A+ 110; reading this, I understood that we need a board to connect to the NUOS and a ESP32 for WiFiing, right?

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Maybe connecting an esp to the rj12 directly using the port 5v to power the esp, and then with esphome try to get the bus communications ? What do you think ?

The Ariston nous Evo + doesnt have that ebus pins.

Hi, someone has made some progress for to integrate Ariston Nuos Evo+ to home assistant?
If not, do you have any alternative method tomonitor the water temperature inside Nuos?