rfid_reader.rb

require "serialport"

@rfid_reader = SerialPort.new 4 # Open COM 5
@arduino = SerialPort.new 2 # Open COM 3

@valid_ids = ['4500B8D690BB']

def readRFID
  rfid = @rfid_reader.gets
  rfid.strip!
  rfid.slice(0) if rfid.size == 13
  rfid.slice(0..1) if rfid.size == 14

  return rfid
end

puts "Waiting for input..."
loop do
  rfid = readRFID # Get the RFID of the current card
  if !rfid.empty? 
    if @valid_ids.include? rfid # is the ID valid?
      puts "RFID: " + rfid

      # Send the arduino a signal so it opens the lock.
      @arduino.write "1" 
    else
      puts "Invalid RFID: " + rfid
      @arduino.write ""
    end
  end
  @arduino.write ""
end