EmonHub support for Samsung Heatpump Monitoring via Mobus

I’ve recently installed a Samsung ASHP (AE050RXYDEG-EU) at my house. Even though I’ve installed full Level 3 heat pump monitoring with a heat meter I’ve also been experimenting with communicating directly with the unit itself.

Using the Samsung Modbus Module and a Modbus to USB adaptor I’ve been able to extract the following data:


I started with a simple python script to read the modbus registers which are documented in the modbus module documentation. It’s possible possible to send control commands, see my test script for details:

Thanks to Homely Energy for helping me get started with this. HomelyEnergy make a smart controller which is compatible with Samsung heatpumps via the same modbus module, they’ve made an excellent video on how to install the modbus module in the outdoor unit.

I don’t have any personal experience with the Homely controller, but it sounds very impressive and has the potential to significantly improve performance of the heatpump, I may try it out myself in the future.

I’ve now added support into EmonHub (V2.3.4 currently in master branch) to read the data and post to Emoncms:

Example emonhub config:

    Type = EmonHubMinimalModbusInterfacer
        device = /dev/ttyUSB0
        baud = 9600
        pubchannels = ToEmonCMS,
        read_interval = 10
        nodename = samsung-ashp
        # prefix = sdm_
                address = 1
                registers = 75,74,72,65,66,68,52,59,58,2,79
                names = dhw_temp,dhw_target,dhw_status,return_temp,flow_temp,flow_target,heating_status,indoor_temp,indoor_target, defrost_status, away_status
                scales = 0.1,0.1,1,0.1,0.1,0.1,1,0.1,0,1,1

It’s nice to have access to this data directly, but unfortunately data like power consumption and flow rate are not available via modbus. Therefore, it’s not possible to calculate COP from this data. However, the Samsung ASHP uses an external Skia flow meter which is usually located indoors, it should be possible to read from the flow meter, then with the addition of CT based power monitoring we will be able to calculate COP without the need for an invasive heat meter. The same (or very similar) Sika flow meters are also used in Mitsubishi EcoDan and Vaillant Arotherm units.

Update: there are some hidden registers which report flow rate, I’ll be adding this into EmonHub soon. With the addition of an energy monitor we will now be able to calculate COP without a heat meter :slight_smile:

See this thread for ongoing efforts to read from the Skia flow meter:


Strictly speaking, that’s actually an RS-485 to USB adaptor. :grin:
(I did notice that the OEM Shop listing contains the term RS-485)

Modbus can use RS-232, RS-422 and TCP (as in TCP/IP) as its transport “mechanism.” :wink:

The aim here is to head off any confusion for users just getting started with / learning about, Modbus


I’ve had 2 of those fail over the years. Not overly robust IME.

Looks a good project though.

I can recall at least one of mine biting the dust too.
They’re so cheap, I bought half a dozen of them. (one to use, and a few to lose) :wink: :smile:


I switched to this one about 5 years ago:

and bought one of these about two years ago:

and haven’t had any problems with either one.

That, it does.

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I’ve not had one fail, but I agree they don’t seem overly robust. I’m considering stocking this adaptor in thr shop instead. I link the fact its got a GND and plenty of protection mechanisms e.g fuses, esd, isolation etc. Its a bit more expensive though, but totally worth it if it stops expensive hardware from being damaged:

Here’s an example of the data in Emoncms:


Thanks for sharing your work on this, it’s very impressive. I had the Samsung AE080RXYDEG (8KW 6th Gen) heat pump installed and while I’m very happy with how it works, getting any data from it has seemed impossible until now.

I have looked at the Homely system and I’m interested in their plans to also integrate solar panels and home batteries. Their system needs the modbus module anyway so your configuration looks like an ideal next step.

I’m new here but happy to help in any way I can.

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Great to hear, let know how you get on. The first step will be to get hold of a modbus module. I’ve just found some hidden registers which report flow rate to enable COP monitoring with just an energy monitor will now be possible :smiley:

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