require "serialport"

#params for serial port
port_str = "/dev/ttyACM0"  #may be different for you
baud_rate = 9600
data_bits = 8
stop_bits = 1
parity = SerialPort::NONE

 sp = SerialPort.new(port_str, baud_rate, data_bits, stop_bits, parity)

  #just read forever
  while true do
     while (i = sp.gets.chomp) do       # see note 2
           puts i
                 #puts i.class #String
                     end
                     end

                      sp.close                       #see note 1