MQTT implementation


I have a device using MQTT instead of modbus that I should connect to openems.
is there any project to implement MQTT?

Hi Siden,

no, not that I know of. So your use-case is to receive data e.g. of a meter or any other device from a MQTT broker, right? Do you need support with the implementation?

Hello, I have a new inverter to implement and it uses MQTT and HTTP to send the command and get the infos from the inverter.
I’m in contact with the inverter developpers and they may do something with modbus.
So my point is more to implement the device himself than the communication protocol.
I can use a MQTT to modbus translator later to make it work with openems.

who can help me to developp this new device quite quickly?

I don’t know about ‘quite quickly’, but my organisation would be interested in integrating a MQTT broker into OpenEMS. The most likely approach would be to simply map certain device channels as MQTT topics, and allow the broker daemon to handle authentication. There would also likely have to be some logic as to which topics are read only, write only or read/write.

Integrating an MQTT broker into OpenEMS would also allow for an alternate generic interface for all devices, allowing, for example, an MQTT edge device to publish control values to the Modbus registries of a meter or inverter

Is there any public documentation about the inverter and its MQTT and HTTP interface available?

If you are planning to implement the inverter yourself, we’ll be glad to support you here in the community forums. Also it might be possible, that other members of the community are also interested in implementing the same/similar devices - like @KyleMicrocare already mentioned. In that case it is best to share as much information as possible, so that we are able to find overlaps.

If you are searching for professional software developers to contract, I would recommend looking at the OpenEMS Association members. There are also some members specializing on software development using OpenEMS. See

Hello, MQTT for the inverter is not mandatory, the inverter builder may supply a modbus connection.
But I would like to connect a smappee meter which uses mqtt protocol that I can give the documentation about that.

Smappee Infinity MQTT.pdf (536.6 KB)

who can I contact as developper for openems? I contacted consolinno but no answers since last week.

Ok, that smappee meter seems to be an interesting product. I’m pinging again Consolinno here (@p.wimmer, @k.nagl). In rest I recommend contacting Christian Lehne from Opernikus, SEEL GmbH or Fractal from Croatia.

Interesting indeed. @stefan.feilmeier, would there be interest from your perspective for someone (perhaps myself) to integrate an MQTT broker directly into OpenEMS, or would it be better to just subscribe to topics on an external broker service?

hi siden,
whom did you contact? there must be a misstake somewhere.
please use
We also did no mqtt implementation right now to OpenEMS.
thank you, best regards.

Sorry for my late response, I missed this thread accidently. I am in touch with Siden and we are discussing some details.

Regarding MQTT:
I want to integrate the smappee meter using MQTT. I think the best way would be to have a MQTT Broker as bridge/controller in OpenEMS. There seems to be some more interest on MQTT! Would it be a good idea to have some more general discussion on this topic in two weeks at the OpenEMS association meeting?

Is there any progress on this topic?
We have a MQTT Broker that provides home are network (LAN) data of price signals and grid information. This allows any MQTT device to react on the GreenPowerIndex (GrünstromIndex) for any sort of load management/grid awareness/demand responds scenarios.

So the actual demand I see for OpenEMS (edge) is a MQTT client not a broker - this would even provide access to Smappee devices, TQ Systems EM400 based submeters or Heidelberg Wallboxes.

Hi Thorsten,

as far as I know nothing happened in this direction yet, but MQTT is a topic that comes up very frequently. I am personally lacking in-depth knowledge about MQTT so I am not able to design a good software architecture for OpenEMS yet - but implementing it as a “MQTT Bridge” just like we have for Modbus/MBus/OneWire/… seems to be the right way to go.

As MQTT is an important topic with many possible use-cases I would like to suggest that we work on a proposal to clearly define it (just like we did for Edge-to-Edge communication) @p.wimmer, @c.lehne and @zoernert might be the good people to talk to about this.

That MQTT Broker for GSI you are talking about: Is it a software product or a hardware device? Maybe even integrated in Discovergy smart meters? Can we try it?

Hi Thorsten,
Regarding the smappee device we wrote a driver with direct access to the smappee power box (via modbus rs485). Unfortunately we can’t make this driver open source (yet).
So no, I didn’t work on the MQTT driver. You are right, a MQTT Client would be enough for most scenarios.
I agree with @stefan.feilmeier, we should start a new proposal for a possible MQTT bridge architecture. Next week I will have some time to take a closer look at the eclipse paho mqtt client. It should be easy to integrate it in OpenEMS, because it is already part of eclipse Kura. When I have a deeper understanding of the paho api, I will make a proposal for a possible MQTT OpenEMS bridge design.

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