dnp3py

A pure Python implementation of the DNP3 (IEEE 1815-2012) protocol.

Features

• Pure Python - No C/C++ dependencies, works anywhere Python runs
• Level 2 Subset - RTU-class functionality for SCADA applications
• Async I/O - Built on asyncio for efficient network communication
• Type Safe - Full type annotations with strict mypy compliance
• Well Tested - Comprehensive test suite with 98%+ code coverage

Installation

pip install dnp3py

Or with pixi:

pixi add dnp3py

Quick Start

Outstation (Server)

import asyncio
from dnp3.database import Database, BinaryInputConfig, AnalogInputConfig
from dnp3.outstation import Outstation
from dnp3.transport_io import TcpServer

async def main():
    # Create database with points
    database = Database()
    database.add_binary_input(0, BinaryInputConfig())
    database.add_analog_input(0, AnalogInputConfig())

    # Update values
    database.update_binary_input(0, value=True)
    database.update_analog_input(0, value=25.5)

    # Create outstation
    outstation = Outstation(database=database)

    # Start TCP server
    server = TcpServer(host="0.0.0.0", port=20000)
    await server.start()

    # Handle connections...

asyncio.run(main())

Master (Client)

import asyncio
from dnp3.master import Master, DefaultSOEHandler
from dnp3.transport_io import TcpClientChannel

async def main():
    # Create master with event handler
    handler = DefaultSOEHandler()
    master = Master(handler=handler)

    # Connect to outstation
    channel = TcpClientChannel(host="localhost", port=20000)
    await channel.open()

    # Perform integrity poll
    request = master.build_integrity_poll()
    # Send request, receive response...

asyncio.run(main())

Supported Features

Function Codes

• READ, WRITE
• SELECT, OPERATE, DIRECT_OPERATE
• COLD_RESTART, WARM_RESTART
• ENABLE_UNSOLICITED, DISABLE_UNSOLICITED
• DELAY_MEASURE

Object Groups

| Group | Description | |-------|-------------| | 1, 2 | Binary Input (static, event) | | 10, 11, 12 | Binary Output (static, event, CROB) | | 20, 21, 22 | Counter (static, frozen, event) | | 30, 32 | Analog Input (static, event) | | 40, 41, 42 | Analog Output (static, command, event) | | 50, 51, 52 | Time objects | | 60 | Class data |

Development

Setup

# Clone repository
git clone https://github.com/craig8/dnp3py.git
cd dnp3py

# Install with pixi
pixi install
pixi run dev-install

# Set up pre-commit hooks (enforces quality checks before commits)
pixi run pre-commit-install

# Run tests
pixi run test

# Run with coverage
pixi run test-cov

# Lint and type check
pixi run check

# Test with specific Python version
pixi run -e py310 test
pixi run -e py312 test

# Test all Python versions (via nox)
pixi run nox

Project Structure

dnp3py/
├── src/dnp3/
│   ├── core/           # CRC, types, enums, flags
│   ├── datalink/       # Data link layer (frames, parsing)
│   ├── transport/      # Transport layer (segmentation)
│   ├── application/    # Application layer (messages)
│   ├── objects/        # DNP3 object definitions
│   ├── database/       # Point database and events
│   ├── outstation/     # Outstation implementation
│   ├── master/         # Master implementation
│   └── transport_io/   # TCP/simulator channels
└── tests/
    ├── unit/           # Unit tests
    └── integration/    # Integration tests

License

MIT License - see LICENSE for details.

Acknowledgments

This implementation follows the IEEE 1815-2012 standard for DNP3.