pyfastnet

Fastnet is the propriatory protocol used by B&G on some older instruments, tested on Hydra/H2000. It might work on other systems. I developed this for personal use and publishing for general interest only.

Purpose

This library can be fed a stream of fastnet data, it will decode and return structured instrument data for further processing. Syncronisation, checksum and decoding is handled by the library.

Example input/output

Byte string from Fastnet including "FF051601E555610030566100185903A86B7F8700BB00016D08CD0DCB"

to_address: Entire System
from_address: Normal CPU (Wind Board in H2000)
command: Broadcast

• True Wind Speed (Knots):

  • channel_id: 0x55
  • interpreted: 4.8

• True Wind Speed (m/s):

  • channel_id: 0x56
  • interpreted: 2.4

• True Wind Angle:

  • channel_id: 0x59
  • interpreted: 107.0

• Velocity Made Good (Knots):

  • channel_id: 0x7F
  • interpreted: 0.01

• True Wind Direction:

  • channel_id: 0x6D
  • interpreted: 269.0

Important library calls - function

• fastnetframebuffer.add_to_buffer(raw_input_data)
• fastnetframebuffer.get_complete_frames()

# Important library calls - debug

• set_log_level(DEBUG)
• fastnetframebuffer.get_buffer_size()
• fastnetframebuffer.get_buffer_contents()

Companion App

• A full implementation can be found here, it takes input from a serial port or dummy file and broadcasts NMEA messages via UDP fastnet2ip

Installation

pip3 install pyfastnet

On a raspberry pi and some other systems this is done from with a virtual env

source ~/python_environment/bin/activate
pip3 install pyfastnet
deactivate
~/python_environment/bin/python3 pyfastnet.py -h 

Acknowledgments / References

• trlafleur - Collector of significant background
• Oppedijk - Background
• timmathews - Significant implementation in Cpp
• Significant help from chatGPT!