Smart One 365 heating controller in NZ

Hi everyone,

I’m integrating a Eurotherm SmartComfort 365 underfloor heating system (using SmartOne365 wall controllers) into Home Assistant via Modbus TCP.

I’ve successfully mapped the documented registers from the Rev.06 protocol, including:

  • Floor temperature
  • Humidity
  • Dew point
  • Target temperature
  • Manual setpoint
  • Mode
  • Flow temperature
  • Flow setpoint

These are all working correctly in Home Assistant.

The one thing I can’t find is a register (or status bit) indicating that a zone is actively calling for heat (i.e. equivalent to the heating/flame icon shown on the SmartOne365 controller).

I’ve already:

  • Compared documented and undocumented registers.
  • Scanned a number of undocumented register ranges.
  • Confirmed the system is definitely heating while testing.
  • Identified that some undocumented registers change continuously, but none appear to be a simple heating-demand flag.

Has anyone:

  • Found a Modbus register or bit indicating heating demand, relay output, valve open, heat request, or similar?
  • Reverse engineered additional SmartComfort 365 registers beyond the published documentation?
  • Integrated one of these systems into Home Assistant?

I’d be very interested in any undocumented register maps or even observations about which registers change during a heating cycle.

Thanks!

Bit decoding using the protocol wizard may help.