Fronius Symo 6.0-3-M inverter

Table of Contents

The Fronius Symo 6.0-3-M is a 6 kW 3-phase grid-tie inverter that is currently a part of my home PV setup. This is a repository of all of the information I was able to gather on this device, some easy, some other a bit harder to find.

1. Interfaces

Aside the obvious DC and AC inputs the inverter has a number of interfaces for monitoring and integration to different systems.


The DATCOM bus is RS-485 based and documented in Fronius DATCOM Detail.

1.2. The Datamanager card

The Datamanager card is an optional datalogger and interface card installed in the inverter which allows for it to connect to the internet and have additional I/O interfaces. The Fronius part number of this particular card is 4,240,038,Z and it can be found on eBay if you look for that symbol.

There also exists a different model of the Datamanager card with a PN 4,240,034,Z which I believe is meant for different inverter line (IG Plus).

Some information about the card's capabilities (albeit for an older model) is provided on the Fronius site as document ref 42,0426,0169.

1.2.1. Ethernet

The card has an ordinary 100MBit RJ-45 socket.

1.2.2. WLAN

  1. Fronius Solar JSON API

    The Datamanager card exposes a JSON API which is used by the inverter management page to which you can browse on port 80 of the Datamanager card's IP. There are two versions of the API which provide slightly different features:

    The different APIs are supported based on the software version on the inverter as described in Fronius Solar API Compatibility. Fortunately Fronius seems to be well-organized in that regard and all of the docs have identifiers which are easily found with a simple web search.

    Many people have been using the JSON API to integrate Fronius with OpenHab (, and Home Assistant.

    There are also python modules to wrap the JSON requests in an API, for example pyfronius.


    The Datamanager card implements a MODBUS interface via RS485 and via TCP over the LAN. The interface is named "SunSpec" and it may be compatible with the specs from but I have not verified that. Fronius provides docs for the MODBUS intefrace on their own site also under the IDs of 42,0410,2049 and 42,0410,2108 where stuff is described.

  3. Fronius Push Service

    The Datamanager card can also upload logs to an FTP server and this is called a Push Service. It's documented on the Fronius site when you search for Push Service and find a training document. I have not yet used this interface as well.

1.2.3. USB

The inverter also has a USB port used for firmware update. This process has been already documented by others for example on Youtube.

I have managed to download the currently available firmware files and they appear to be encrypted. They are mirrored here.

2. Other

I found some references to using MODBUS for Fronius inverter monitoring in the EU SHAR-Q project paper.

3. References

Fronius ref Description Link Notes
42,0410,2011 Fronius Solar API V0  
42,0410,2012 Fronius Solar API V1  
42,0410,2049 Fronius Datamanager Modbus TCP & RTU  
42,0426,0169 Fronius Datamanager  
42,0410,2108 Fronius Datamanager 2.0 Modbus RTU Quickstart Guide,0410,2108.pdf  
42,0426,0191,EA Fronius Datamanager 2.0 / Fronius Datamanager Box 2.0,0426,0191,EA.pdf  
42,0410,2020 Fronius Solar API Compatibility  
42,0410,0968 Fronius DATCOM Detail,0410,0968.pdf  
  Numeric fault codes  
  Storage capacity sharing over virtual neighbourhoods of energy ecosystems  

Author: Maciej Grela <>