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.


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. The JSON API documentation is freely available on the Fronius site under the document ID 42,0410,2012. 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.

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
42,0410,2012 Fronius Solar API V1 Energy/Operating Instructions/42,0410,2012.pdf  
42,0410,2049 Fronius Datamanager Modbus TCP & RTU Energy/Operating Instructions/42,0410,2049.pdf  
  SETTING UP THE LOCAL FTP SERVER Energy/Operating Instructions/SE_OI_Setting_up_the local_FTP_server_EN.pdf  
42,0426,0169 Fronius Datamanager Energy/Operating Instructions/42,0426,0169,EA.pdf  
42,0410,2108 Fronius Datamanager 2.0 Modbus RTU Quickstart Guide Energy/User Information/42,0410,2108.pdf  
  Numeric fault codes  
  Storage capacity sharing over virtual neighbourhoods of energy ecosystems  

Created: 2020-08-09 21:26