Integrating a Daikin A/C System

Hi All,

New project starts today for me! :tada:

I will share here the experiences during the development/building phase.

Scope: Integrate within openHAB2 my existing Daikin A/C system composed of:

  1. Daikin 13,3 kW cooling power, 3-phase cold only - air cooled (propeller fan) mini inverter chiller (SKU: EWAQ013ACW1P)
    Product pdf (511.7 KB) Piping diagrams (615.7 KB) Dimensions (615.4 KB) Wiring Diagram (618.0 KB)


  1. Daikin Indoor User interface (SKU: ARC448A3) connected on the proprietary Daikin P1/P2 Bus

Big thanx to @george.erhan who pointed out that I can use the IntesisBox DK-RC-KNX-1 solution to integrate this system into my KNX installation !

It looks like IntesisBox is great and they are making a lot of different solutions for communicating to several A/C units!

More news soon!

A new HABPanel layout will be build (so I can get rid of that ugly interior control unit) with all A/C related info… I am thinking to install “smart” flow & temp meters to monitor each piping circuit individually so I can display this on my A/C dashboard :slight_smile:

Hey thermostat, we cool?

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Well… it seems that my suggestion does not work! The guys from Intesis do not support standalone monoblock chillers (as @Dim found out today)
They only deal with the control of the indoor units in terms of KNX communication!
The only possible integration right now is using RS485, like stated here.
Sorry for the wrong information!

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George, without your suggestion, I would have never investigated the possible options :slight_smile:
I had already given up on integrating the A/C system in openHAB but now, I am determined to do it and I am grateful for your help. We will fix it for sure ! :slight_smile:

Ps: Intesis mentioned that they don’t have a compatible solution for Monoblock Chillers (like mine) and they also don’t support Altherma units (just fyi)

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More bad news came from the Daikin support office:

The only option to control this monoblock chiller is to use an I/O PCB that provides only remote On/Off (no full control of all parameters) :frowning:

They proposed: SKU EKRP1HBA

This I/O card offers 3 voltage free outputs: On/Off, Alarm, other

I am not sure if I will proceed since I don’t think that it’s worth spending 150 € just to be able to turn On/Off the chiller…
Maybe it’s time to dig out my trusted ESP8266s and play with them to see if I can do the same (or better) with 5 € :slight_smile:

Sorry to necroing this thread, I couldn’t find a way to directly send you a PM.
I have a very similar monoblock Daikin heat pump, and exactly the same indoor interface.
I’ve recently installed a kWh-counter to monitor the A/C electricity consumption and I created an Arduino board with datalogging functions.
Then I thought, it’d be great to associate the power adsorption with the external and water temperatures. So I started investigating if a system to add to the indoor interface (or to replace it completely) existed, and I found this thread with your previous attempts.
So, one year later, have you found a way to do that?
Thanks a lot

Hi Stefano,

Unfortunately… not…

Daikin told me that there is no way to communicate with my monoblock unit… only On/Off commands :frowning:

I haven’t done anything with this yet… i am planning to use an ESP and some code to enable On/Off and maybe dig into the comms of the P1/P2 Bus to see if I can pull out more info.

It’s good that you reminded me! :slight_smile:
This is a nice project for the weekend… I will let you know what I find from sniffing the comms on the Daikin P1/P2 Bus between the indoor controller and the monoblock :+1:

Thanks a lot, look forward to it!!
In all honesty, going through the sniffing and all would have been way beyond my capabilities :slight_smile:

have you looked at whether coolmasternet supports it? Expensive but extremely robust and reliable, and a well documented interface.

Thanx @dan12345
I checked their website but they don’t have my model listed under the supported Daikin models
I just dropped them an email on and I am waiting their reply
For now, I am getting ready to attach a serial sniffer on the P1/P2 Bus to see what characters I can grab when sending commands from the indoor control unit to the monoblock.

edit: I saw a reference to P1/P2 Daikin Bus on their CoolPlug DK (Daikin) which works with CooLinkNet.
We are talking about: 650+500 USD … that’s way too much :frowning:

yeah, the coolmasternet equipment is really expensive - no getting round it.

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got it (from their CEO on a Saturday night :slight_smile:)

Is it possible to get an Infra Red remote control or an over the internet control for your unit? I have a Mitsubishi Electric Ducted AC that had a similar control panel and I added the optional infra red remote receiver. I then recorded the commands sent by the remote and I replay them using OpenHAB and a IR sender. One problem though is Daikin remote commands are long and hard to record and playback although a few on the net seem to have hacked them.

Unfortunately, no.
The interior unit doesn’t have IR support and the system is a bit old so there are no modern modules to expand it for any kind remote control :frowning: (only remote On/Off using a digital I/O board)

The only option for me is to (try to) hack the P1/P2 Bus comms :slight_smile:

This Daikin unit is a water chiller. My house is watercooled (like a CPU/GPU :slight_smile:)

Great to see your determination! I think a lot of people would love to see the P1/P2 interface hacked. I do not have the skills to do that myself, but at least I will try to contribute with what I have found out about P1/P2 hacking so far.

The most serious attempt to hack the P1/P2 interface came few years ago from some Italian guys here:

They used oscilloscope to analyse the interface. They found out that the P1/P2 interface uses the Home Bus System (HBS) communication protocol specified in the ET-2101 standard by the Electronic Industries Association of Japan. And they got stuck here because they were not able to find details about the ET-2101 HBS protocol…

I was actually able to find some details about the ET-2101 HBS protocol in this document:

(see chapter 4: Extended HBS communication protocol starting at page 107).

Hope it helps you…

… and some Turkish forum:

Based on the hints and links by Krakra, I wrote and released a P1P2Monitor program and P1P2Serial library to read the data on the P1/P2 interface using a small adapter circuit and an Arduino Uno. Documentation and code is on Some of the data format has been reverse engineered and is documented in the doc directory on github. There is still a lot of work to do. Different heat pumps use different communication protocols over this interface, so please share your results if you have any.


@Arnold-n - Great work! Ill be following with interest!

@Arnold-n great work. I’m currently reversing Daikin VRF P1P2 protocol and earned good know-how about it. Please contact with me.

Great job Arnold ! I have read your work on decoding the Daiken P1/P2 protocol. Was wondering if you have had a chance compare the Daiken P1/P2 interface with the Mitsubshi M-Net 2-wire protocol. From what I have read, the hardware layer is the same.


That’s what I understood too, but not having any Mitsubishi hardware I can only google. I found an earlier project for the Mitsubishi protocol: which can read (but not write) the Mitsubishi protocol, using generic OPAMPS (impressive) and a circuit which lengthens the 52us pulses to 104us pulses so it becomes a regular 9600 Baud signal. Looking at the protocol description on Github, the Mitsubishi M-Net logical format is different (XOR instead of CRC, and the packet format thus seems to follow the HBS packet format and timing (as documented in the Echonet spec) whereas Daikin ignores the HBS logical format and timing). I think P1P2Serial should be able to read and write the Mitsubishi M-Net bus too.