nmea2000 2025.10.13
NMEA 2000 encoder and decoder
License: Apache-2.0


# NMEA 2000 Python Library

A Python library for encoding and decoding NMEA 2000 frames. The encoding and decoding is based on the extensive [canboat](https://canboat.github.io/canboat/canboat.html) database. It also supports inexpensive CANBUS USB and TCP devices as gateways between your NMEA 2000 boat network and any Python code that wants to receive or send these messages.  
This package is the backend for the Home Assistant [NMEA 2000 Integration](https://github.com/tomer-w/ha-nmea2000).

## Features

- **Decode NMEA 2000 frames**: Parse and interpret raw NMEA 2000 data.
- **Encode NMEA 2000 frames**: Convert structured data back into the NMEA 2000 frame format.
- **USB client**: Send and receive NMEA 2000 data over CANBUS USB devices like [Waveshare USB-CAN-A](https://www.waveshare.com/wiki/USB-CAN-A)
- **TCP client**: Send and receive NMEA 2000 data over CANBUS TCP devices like:
     - [EBYTE ECAN-W01S](https://www.cdebyte.com/products/ECAN-W01S)
     - [EBYTE ECAN-E01](https://www.cdebyte.com/products/ECAN-E01)
     - [Actisense W2K-1](https://actisense.com/products/w2k-1-nmea-2000-wifi-gateway/)
     - [Yacht Devices YDEN-02](https://yachtdevicesus.com/products/nmea-2000-ethernet-gateway-yden-02)
- **PGN-specific parsing**: Handle various PGNs with specific parsing rules based on [canboat](https://canboat.github.io/canboat/canboat.html).
- **Stateful decoder**: The decoder supports NMEA 2000 fast messages, which are split across multiple CANBUS messages.
- **CLI support**: Built-in command-line interface for encoding and decoding frames.

## Installation

You can install the library using `pip`:

```bash
pip install nmea2000
```

Alternatively, you can clone the repository and install it locally:

```bash
git clone https://github.com/tomer-w/nmea2000.git
cd nmea2000
pip install .
```

## Usage

### Decode NMEA 2000 Frame (CLI)

To decode a frame, use the `decode` command followed by the frame in Actisense hex format:

```bash
nmea2000-cli decode --frame "09FF7 0FF00 3F9FDCFFFFFFFFFF"

65280 Furuno: Heave: Manufacturer Code = Furuno (bytes = "3F 07"), Reserved = 3 (bytes = "03"), Industry Code = Marine (bytes = "04"), Heave = -0.036000000000000004 (bytes = "DC"), Reserved = 65535 (bytes = "FF FF 00")
```
```json
Or in JSON format:
{"PGN":65280,"id":"furunoHeave","description":"Furuno: Heave","fields":[{"id":"manufacturer_code","name":"Manufacturer Code","description":"Furuno","unit_of_measurement":"","value":"Furuno","raw_value":1855},{"id":"reserved_11","name":"Reserved","description":"","unit_of_measurement":"","value":3,"raw_value":3},{"id":"industry_code","name":"Industry Code","description":"Marine Industry","unit_of_measurement":"","value":"Marine","raw_value":4},{"id":"heave","name":"Heave","description":"","unit_of_measurement":"m","value":-0.036000000000000004,"raw_value":-36},{"id":"reserved_48","name":"Reserved","description":"","unit_of_measurement":"","value":65535,"raw_value":65535}],"source":9,"destination":255,"priority":7}

```

### Example Code

```python
from nmea2000.decoder import NMEA2000Decoder

# Initialize decoder
decoder = NMEA2000Decoder()

# Decode a frame
frame_str = "09FF7 0FF00 3F9FDCFFFFFFFFFF"
decoded_frame = decoder.decode_actisense_string(frame_str)

# Print decoded frame
print(decoded_frame)
```

### TCP Client CLI

```bash
nmea2000-cli tcp_client --server 192.168.0.46 --port 8881 --type actisense
```

### TCP Client code

```python
async def handle_received_data(message: NMEA2000Message):
    """User-defined callback function for received data."""
    print(f"Callback: Received {message}")
    
client = EByteNmea2000Gateway(ip, port)
client.set_receive_callback(handle_received_data)  # Register callback
```

### Encode NMEA 2000 Frame (CLI)
You can also encode data into NMEA 2000 frames using the `encode` command:

```bash
nmea2000-cli encode --data "your_data_to_encode"
``` 


Example:
```bash
nmea2000-cli encode --data '{"PGN":65280,"id":"furunoHeave","description":"Furuno: Heave","fields":[{"id":"manufacturer_code","name":"Manufacturer Code","description":"Furuno","unit_of_measurement":"","value":"Furuno","raw_value":1855},{"id":"reserved_11","name":"Reserved","description":"","unit_of_measurement":"","value":3,"raw_value":3},{"id":"industry_code","name":"Industry Code","description":"Marine Industry","unit_of_measurement":"","value":"Marine","raw_value":4},{"id":"heave","name":"Heave","description":"","unit_of_measurement":"m","value":-0.036000000000000004,"raw_value":-36},{"id":"reserved_48","name":"Reserved","description":"","unit_of_measurement":"","value":65535,"raw_value":65535}],"source":9,"destination":255,"priority":7}'
Encoding frame: {"PGN":65280,"id":"furunoHeave","description":"Furuno: Heave","fields":[{"id":"manufacturer_code","name":"Manufacturer Code","description":"Furuno","unit_of_measurement":"","value":"Furuno","raw_value":1855},{"id":"reserved_11","name":"Reserved","description":"","unit_of_measurement":"","value":3,"raw_value":3},{"id":"industry_code","name":"Industry Code","description":"Marine Industry","unit_of_measurement":"","value":"Marine","raw_value":4},{"id":"heave","name":"Heave","description":"","unit_of_measurement":"m","value":-0.036000000000000004,"raw_value":-36},{"id":"reserved_48","name":"Reserved","description":"","unit_of_measurement":"","value":65535,"raw_value":65535}],"source":9,"destination":255,"priority":7}'

output:
09FF7 0FF00 3F9FDCFFFFFFFFFF
```



### Example Code
TBD
```python
from nmea2000.encoder import NMEA2000Encoder

# Initialize encoder
encoder = NMEA2000Encoder()

# Data to encode: vessel heading message (PGN 127250)
   message = NMEA2000Message(
        PGN=127250,
        priority=2,
        source=1,
        destination=255,
        fields=[
            NMEA2000Field(
                id="sid",
                raw_value=0,
            ),
            NMEA2000Field(
                id="heading",
                value=1, # 1 radian is 57 degrees
            ),
            NMEA2000Field(
                id="deviation",
                raw_value=0,
            ),
            NMEA2000Field(
                id="variation",
                raw_value=0,
            ),
            NMEA2000Field(
                id="reference",
                raw_value=0,
            ),
            NMEA2000Field(
                id="reserved_58",
                raw_value=0,
            )
        ]
    )

msg_bytes = encoder.encode_ebyte(_generate_test_message())
print(msg_bytes)
```

## Development

Contributions, feedback, and suggestions to improve this project are welcome. If you have ideas for new features, bug fixes, or improvements, feel free to open an issue or create a pull request. I’m always happy to collaborate and learn from the community!

Please don't hesitate to reach out with any questions, comments, or suggestions.

### Setup for Development

To contribute to this library, clone the repository and install the required dependencies:

```bash
git clone https://github.com/tomer-w/nmea2000.git
cd nmea2000
pip install -e .[dev]
```

### Running Tests

To run the tests, use:

```bash
pytest
```

### Running the CLI Locally

To test the CLI locally, you can use the following command:

```bash
python -m nmea2000.cli decode --frame "your_hex_encoded_frame"
```

## License

This project is licensed under the Apache 2.0 license - see the [LICENSE](LICENSE) file for details.

## Acknowledgements

- This library leverages the [canboat](https://github.com/canboat/canboat) as the source for all PGN data.
- Special thanks to Rob from [Smart Boat Innovations](https://github.com/SmartBoatInnovations/). His code was the initial inspiration for this project. Some of the code here may still be based on his latest open-source version.