kermi-xcenter 0.2.1

Async Python interface for Kermi heat pumps via Modbus

Kermi Modbus

Async Python interface for Kermi heat pumps via Modbus (TCP/RTU).

Features

• ✨ Async/await support - Modern async Python using asyncio
• 🔌 TCP and RTU - Supports both Modbus TCP and RTU connections
• 📊 Three device types - Heat Pump, Storage System, and Universal Module
• 🎯 Fully typed - Complete type hints for better IDE support
• 🛡️ Type-safe enums - Status and mode values as Python enums
• 🔄 Auto-conversion - Automatic data type conversions (temperatures, power, COP, etc.)
• ✅ Validation - Input validation with range checks
• 🔁 Retry logic - Automatic retries with exponential backoff
• 📝 Well documented - Comprehensive docstrings and examples

Installation

pip install -e .

For development:

pip install -e ".[dev]"

Quick Start

import asyncio
from kermi_xcenter import KermiModbusClient, HeatPump

async def main():
    # Create client
    client = KermiModbusClient(host="192.168.1.100", port=502)

    # Create heat pump device (unit ID 40)
    heat_pump = HeatPump(client)

    # Connect and read values
    async with client:
        # Read temperatures
        outdoor_temp = await heat_pump.get_outdoor_temperature()
        supply_temp = await heat_pump.get_supply_temp_heat_pump()

        # Read COP (Coefficient of Performance)
        cop = await heat_pump.get_cop_total()

        # Read power
        power_thermal = await heat_pump.get_power_total()
        power_electrical = await heat_pump.get_power_electrical_total()

        # Get status
        status = await heat_pump.get_heat_pump_status()

        print(f"Outdoor: {outdoor_temp}°C")
        print(f"Supply:  {supply_temp}°C")
        print(f"COP:     {cop}")
        print(f"Power:   {power_thermal} kW (thermal), {power_electrical} kW (electrical)")
        print(f"Status:  {status.name}")

asyncio.run(main())

Supported Devices

Heat Pump (Unit ID 40)

Main heat pump control with access to:

• Energy source temperatures
• Heat pump circuit (supply, return, flow rate)
• COP values (total, heating, hot water, cooling)
• Power measurements (thermal and electrical)
• Operating hours (fan, compressor, pumps)
• Status and alarms
• PV modulation controls

from kermi_xcenter import HeatPump

heat_pump = HeatPump(client, unit_id=40)
cop = await heat_pump.get_cop_total()
await heat_pump.set_pv_modulation_power(2000)  # 2000W

Storage System (Units 50/51)

Heating storage (50) and hot water storage (51):

• Storage temperatures (heating, cooling, hot water)
• Heating circuit control
• Operating modes and energy settings
• Season selection
• External heat generator control
• Temperature sensors
• Operating hours

from kermi_xcenter import StorageSystem, EnergyMode

heating_storage = StorageSystem(client, unit_id=50)
hot_water_storage = StorageSystem(client, unit_id=51)

temp = await heating_storage.get_heating_actual()
await hot_water_storage.set_hot_water_setpoint_constant(50.0)
await heating_storage.set_heating_circuit_energy_mode(EnergyMode.ECO)

Universal Module (Unit ID 30)

Additional heating circuits with:

• Heating circuit control and status
• Operating modes and energy settings
• Season selection
• Temperature sensors
• Operating hours

from kermi_xcenter import UniversalModule, EnergyMode

universal = UniversalModule(client, unit_id=30)
await universal.set_energy_mode(EnergyMode.COMFORT)

Connection Types

TCP Connection

client = KermiModbusClient(
    host="192.168.1.100",
    port=502,
    timeout=3.0,
    retries=3
)

RTU Connection

client = KermiModbusClient(
    port="/dev/ttyUSB0",
    baudrate=9600,
    use_rtu=True,
    timeout=3.0
)

Examples

See the examples/ directory for complete examples:

• basic_monitoring.py - Read temperatures, COP, power, and status
• pv_modulation.py - Control PV modulation for solar integration
• storage_control.py - Control heating and hot water storage
• continuous_monitoring.py - Continuous monitoring with periodic updates

Run an example:

python examples/basic_monitoring.py

Data Types and Enums

The library provides type-safe enums for all status and mode values:

from kermi_xcenter import (
    HeatPumpStatus,           # STANDBY, ALARM, HOT_WATER, COOLING, HEATING, etc.
    HeatingCircuitStatus,     # OFF, HEATING, COOLING, DEW_POINT, etc.
    OperatingMode,            # OFF, HEATING, COOLING
    OperatingType,            # AUTO, HEATING
    EnergyMode,               # OFF, ECO, NORMAL, COMFORT, CUSTOM
    SeasonSelection,          # AUTO, HEATING, COOLING, OFF
    ExternalHeatGeneratorMode,  # AUTO, HEAT_PUMP_ONLY, BOTH, SECONDARY_ONLY
)

Automatic Data Conversion

All register values are automatically converted to engineering units:

• Temperatures: Stored as INT16 in 0.1°C units, returned as float in °C
• Power: Stored as UINT16 in 0.01 kW units, returned as float in kW
• COP: Stored as UINT16 in 0.01 units, returned as float
• Flow rate: Stored as UINT16 in 0.1 l/min units, returned as float in l/min
• Booleans: Stored as UINT16 (0/1), returned as bool
• Enums: Stored as UINT16, returned as typed enum instances

Error Handling

The library provides custom exceptions for different error scenarios:

from kermi_xcenter import (
    KermiModbusError,          # Base exception
    ConnectionError,           # Connection failed
    RegisterReadError,         # Read operation failed
    RegisterWriteError,        # Write operation failed
    ValidationError,           # Value out of range
    ReadOnlyRegisterError,     # Attempted write to read-only register
)

try:
    temp = await heat_pump.get_outdoor_temperature()
except RegisterReadError as e:
    print(f"Failed to read register {e.address}: {e}")
except ConnectionError as e:
    print(f"Connection failed: {e}")

Register Documentation

All register names use English for code clarity, with German equivalents preserved in docstrings:

# English method name
outdoor_temp = await heat_pump.get_outdoor_temperature()

# Docstring includes German reference:
# """Get outdoor temperature in °C.
#
# Kermi code: BOT, Register: 3
# German: Außentemperaturfühler
# """

Complete register specification: docs/modbus_specification.md

Architecture

kermi_xcenter/
├── client.py              # Async Modbus client (TCP/RTU)
├── registers.py           # Register definitions for all modules
├── types.py               # Enums and type aliases
├── exceptions.py          # Custom exceptions
├── utils/
│   └── conversions.py     # Data type conversion functions
└── models/
    ├── base.py            # Base device class
    ├── heat_pump.py       # Heat pump (unit 40)
    ├── storage_system.py  # Storage system (units 50/51)
    └── universal_module.py # Universal module (unit 30)

Development

Setup

# Create virtual environment
python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

# Install with dev dependencies
pip install -e ".[dev]"

# Install pre-commit hooks
pre-commit install

Code Quality

# Format code
black src/ tests/ examples/

# Lint
ruff check src/ tests/ examples/

# Type check
mypy src/

Testing

# Run tests
pytest

# With coverage
pytest --cov=kermi_xcenter --cov-report=html

Modbus Function Codes

The library supports the following Modbus function codes:

• 0x03 - Read Holding Registers
• 0x06 - Write Single Register
• 0x10 - Write Multiple Registers

Requirements

• Python 3.12+
• pymodbus >= 3.6.0

License

Apache License 2.0 - see LICENSE file for details.

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes with tests
4. Ensure code passes linting and type checking
5. Submit a pull request

Credits

This library is not affiliated with or endorsed by Kermi GmbH.

Documentation

• Modbus Specification - Complete register maps
• Project Plan - Architecture and design decisions

Support

For issues and questions:

• Create an issue on GitHub
• Check existing documentation in docs/
• Review examples in examples/

Changelog

0.1.0 (2025-01-XX)

• Initial release
• Async/await support for all operations
• Support for three device types (Heat Pump, Storage System, Universal Module)
• Complete register definitions with English names
• Type-safe enums for all status and mode values
• Automatic data conversions
• TCP and RTU connection support
• Comprehensive examples