read_anemometer.rb

#!/usr/bin/env ruby

# Reads the anemometer "Holdpeak HP-866A" from USB port
# Time stamp in unix time and windspeed in m/s is output

require 'rubyserial'

if ARGV.length != 1
	$stderr.puts "usage: read_anemometer.rb <tty device>"
	exit(-1)
end

serialport = Serial.new ARGV.shift, 9600

buffer = []
loop do
	buffer = buffer + serialport.read(9999).bytes
	buffer = buffer.drop_while {|x| x != 0xeb }
	if buffer.length >= 15
		b = buffer[2..15]
		a, b = b.pack("c*").unpack("S>*")[-2..-1]
		if a == b
			puts "% 15.1f % 3.2f" % [Time.now.to_f, (a * 0.01)]
		end
		buffer = []
	end
end