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Wolf ebusd messages configuration

eBus configuration files for Wolf heating systems – BM-2 / FHA / MM-2

Overview

This repository contains the .csv configuration files I currently use with ebusd to monitor and control a Wolf heating system based on an FHA heat pump.

The master folder includes a calculation sheet listing all parameters (260+) that I have decoded by analyzing the eBus traffic of my system.

The parameter list is based on information shared by other users — in particular the excellent work by zivillian — and my own additional reverse engineering effort to decode messages for newer Wolf models, particularly the FHA heat pump family.

System Configuration

My installation consists of:

  • FHA split heat pump (master 3 - slave 8)
  • BM-2 room controller (master 30 - slaves 35 & 85)
  • MM-2 mixer module (slaves 51)
  • Wolfnet interface (master ff)
  • Unknown controller (master 70 / slave 75)

The system includes:

  • Floor heating
  • 200 L domestic hot water (DHW) tank

The unknown controller at address 70/75 is a Kromschroeder unit, possibly embedded into the FHA and controlling valves in the FHA IDU and ODU. I have no firm evidence of this deduction and would welcome any insight to confirm or reject this option.

eBus Messaging Details

In this topology, both the BM-2 and the Wolfnet interface periodically poll other devices to read parameter values.

BM-2 Behavior

  • Polls single parameters per read request
  • Sends setpoints to the FHA and MM-2
  • Provides internal room temperature measurements

Wolfnet Behavior

  • Continuously reads parameters even when no user is connected
  • Expands the set of requested parameters when a user is connected, depending on the page displayed in the web app
  • Sends write commands when a user changes a setpoint

Unlike the BM-2, Wolfnet typically reads five unrelated parameters in a single message. The parameter combination varies depending on:

  • System state
  • System topology
  • Active user interaction

As a result, multiple message descriptors may exist for messages that include overlapping parameter sets.

Bus Load Considerations

The described topology generates significant eBus traffic:

  • Average bus occupancy exceeds 40% of bandwidth
  • Occasional saturation at ~218 symbols/sec

For this reason, my monitoring approach prioritizes passive listening rather than active polling.

A dedicated listener.csv file contains all observed message patterns.

Note:

  • The list of Wolfnet read combinations is not exhaustive (message like ff0850220b540200...)

  • Most parameters of interest are read via the BM-2

  • One important exception is room temperature, which originates internally in the BM-2 and must either:

    • Be passively decoded from Wolfnet polling, or
    • Be actively read from the BM-2

Reading from the BM-2 Controller

The BM-2 appears on the eBus as:

  • Master at logical address 30
  • Multiple logical slave addresses

In my system:

  • Slave 35 → Internal controller parameters
  • Slave 85 → Parameters affecting FHA operation

It is unclear whether other heating generators controlled by a BM-2 would appear under different slave addresses.

The configuration files explicitly reference slave 85 where required.

Writing to the BM-2 Controller

Although many parameters can technically be modified, only a limited number of write descriptors (w) are included in the configuration.

This is intentional:

  • Occasional setpoint changes can be handled via the Wolf web app
  • The primary goal of this project is monitoring

Exposed write parameters allow:

  • Enabling/disabling DHW
  • Enabling/disabling floor heating
  • Setting DHW temperature
  • Setting room temperature setpoints

Write Command Structure

Write commands can generally be derived from the corresponding read command by replacing PBSB code 0x5022 with 0x5023.

Writing parameters to the BM-2 controller requires adding a fixed ULG suffix 0x0000015dto the changed value. The constant field is encoded as W in the message descriptor, resulting in a message w NAME 'value;W'.

Known ebusd Limitation

ebusd currently expects every master/slave transaction to include a slave response.

Wolf write commands do not generate a response, resulting in:

ERR: read timeout

This error should be ignored.

See: john30/ebusd#1696

Despite the timeout, the write command is successfully received and executed by the BM-2.

Language Support

The configuration files use English parameter names.

Where possible, terminology matches the wording used in Wolf’s English web interface. However:

  • Some translations may not be ideal
  • Minor inconsistencies may exist, often inherited from the Wolf app wording

Contributions and improvements are very welcome.

Home Assistant Integration

A custom integration for Home Assistant (HA) is provided here. This integration

  • Imports entities directly from ebusd, without the need for an MQTT service
  • Simplifies monitoring and automation
  • Provides structured integration into HA

Disclaimer

These files are the result of personal reverse engineering work performed on my own system.

I am not affiliated with Wolf or any other company.

Use this information at your own risk. I cannot accept responsibility for any direct or indirect damage resulting from its use.

Contributions, corrections, and shared findings from other users are highly appreciated.