password = "on"
antipassword = "off"
exitWord = "exit"

while true do
input = read()

  if input == password then
	Pulse()
  elseif input == antipassword then
    rs.setOutput("back", false)
  elseif input == exitWord then
    return
  end
end

function Pulse()
	rs.setOutput("back", true)
	sleep(1)
	rs.setOutput("back", false)
	sleep(1)
end