Adlar Castra Heat Pump (Modbus)

This app gives Homey Pro local Modbus TCP access to an Adlar Castra / Aurora III heat pump through an Elfin EW11A or another Modbus TCP to RS485 gateway. Daily operation does not depend on cloud access.

Current Implementation Status

• Pairing uses only the Modbus gateway details: IP address, TCP port (default 502) and Modbus Unit ID (default 1).
• The old Tuya fields such as Device ID, Local Key and protocol version are not used in this Modbus app.
• Polling intervals are configurable in the device settings (default superfast/fast/medium/slow: 5 s / 10 s / 30 s / 300 s). Superfast polling can adapt to 2 s after live value changes.
• The current register mapping is aimed at Adlar Castra / Aurora III units.
• The dashboard server includes read-only, interactive, live capability, expert register and register change log dashboards.
• The expert dashboard includes the Aurora III input and holding register map, grouped by function.
• Aurora III temperature registers use x10 scaling (deci-°C).

Requirements

• Homey Pro with firmware 12.2.0 or newer
• Adlar Castra / Aurora III heat pump with Modbus/RS485 connection
• Modbus TCP gateway such as an Elfin EW11A

What Works Today

Readout

• Heating, cooling, DHW and floor heating setpoints
• Outlet, inlet, ambient, coil, suction, exhaust, DHW, economizer, saturation, buffer and zone temperatures
• Power, energy, voltage, current, compressor frequency, fan speed, EEV step, pump PWM and water flow
• Running state, defrost, antifreeze, sterilization and decoded fault information
• Local dashboards at http://<homey-ip>:8090/ by default, including live capability tiles, interactive setpoint controls, expert Modbus tools and register change statistics

Control From Homey

• Main on/off readout; write is blocked until Aurora III register 4-2100 = 0 is hardware-confirmed
• Operating mode and work mode
• Heating setpoint
• Cooling setpoint
• DHW setpoint
• Heating curve preset and hot water curve preset
• Desired indoor temperature for adaptive control
• Direct Modbus register read/write flow cards
• Utility flow cards for generic curve lookup, pre-heat time and time-based value calculations

Calculated Values

• COP and SCOP based on Modbus power, water temperature delta and water flow
• External power, flow, ambient, indoor temperature, energy prices, solar power, solar radiation and wind data can be supplied via flow cards
• Threshold, alert and fault flow cards are available for monitored Modbus values

Current Limitations

• A Modbus TCP gateway is required; this app does not use Tuya cloud or Tuya local credentials.
• The floor heating setpoint is read, displayed and writable from the device capability; there is no dedicated flow action for it yet.
• Advanced Modbus write tools are available through flow cards and the expert dashboard; use them with care.
• COP can be missing or less accurate when usable power or flow data is unavailable.
• Adaptive control, building model learning, weather forecast, price optimization, COP optimization and wind correction are opt-in features. Several of these need external indoor temperature, weather, wind or price data before they can produce useful results.
• This app is Aurora III-only; legacy Aurora II/R32 register maps are not included.

Installation

1. Connect the heat pump RS485/Modbus bus to an Elfin EW11A or equivalent Modbus TCP gateway.
2. Make sure the gateway is reachable from Homey on the local network.
3. Add the Adlar Castra Heat Pump device in Homey.
4. Enter the gateway IP address, TCP port and Modbus Unit ID.
5. Optionally adjust polling intervals and other device settings after pairing.

For EW11A wiring and configuration screenshots, see docs/setup.

Local Dashboards

Open the dashboards from a browser on the same local network as Homey:

• http://<homey-ip>:8090/ — read-only register dashboard with current heat pump values
• http://<homey-ip>:8090/interactive — interactive dashboard with live overview, sparklines and safe setpoint controls
• http://<homey-ip>:8090/live — live capability dashboard grouped by status, setpoints, sensors, power, performance and diagnostics
• http://<homey-ip>:8090/expert — expert register dashboard with Modbus addresses, P/L parameter IDs and live read/write tools
• http://<homey-ip>:8090/changelog — register change log with per-register change counts, intervals and poll-group recommendations

Replace <homey-ip> with the IP address of your Homey Pro. Use the expert dashboard with care: writable Modbus registers can change heat pump behaviour. The default dashboard port is 8090; if you changed the Dashboard port setting, use that port in the URL instead.

Device Settings

• IP address of the Modbus gateway
• TCP port
• Modbus Unit ID
• Dashboard port (default 8090)
• Superfast, fast, medium and slow polling intervals
• COP calculation switch; when disabled, COP and SCOP capability updates are stopped
• Internal power measurement capabilities are enabled by default for Aurora III
• Adaptive control, building model, building insights, weather forecast, price optimization, COP optimization and wind correction remain disabled by default until configured
• Log level

Practical Notes

• Recommended defaults: port 502, Unit ID 1.
• Give the gateway a fixed DHCP lease or static IP address to avoid reconnect issues.