Daikin Altherma + Modbus TCP

Configuration
1

Hi,

I'm trying to monitor my Daikin Altherma heat pump through its built-in Modbus TCP interface (port 502).

Important: I'm not trying to control or modify any settings. My goal is only to read data for energy analysis and diagnostics (COP estimation, compressor behaviour, power consumption, possible cycling/defrost events, etc.).

What I've found so far:

  • Modbus TCP enabled and reachable on port 502
  • Slave ID = 3
  • Register 30775 returns a live value that changes every second
  • Reading register 30775 as a 32-bit value gives values around 700–3000, which looks very much like instantaneous thermal or electrical power
  • Many nearby registers return 4294967295 or Modbus exception responses
  • Read Device Information does not seem to be supported

Example Python test:

r = client.read_input_registers(    address=30775,    count=2,    slave=3)value = (r.registers[0] << 16) + r.registers[1]print(value)

Questions:

  1. Does anyone have a register map for Daikin Altherma Modbus TCP?
  2. Is register 30775 documented somewhere?
  3. Are there registers available for:
  • electrical consumption,
  • compressor frequency,
  • leaving water temperature,
  • return water temperature,
  • DHW temperature,
  • COP / energy counters?
  1. Has anyone successfully integrated these registers into Home Assistant for monitoring purposes?

Any documentation, register lists, or experience would be greatly appreciated.

Thanks!

2

Have you tried the Protocol Wizard to help in your experiments?