startup.lua

rednet.open("top")
local mn = peripheral.wrap("bottom")
local mnb = peripheral.wrap("monitor_11")
local function clear()
  mn.clear()
  mnb.clear()
end
local function setTextColor(clr)
  mn.setTextColor(clr)
  mnb.setTextColor(clr)
end
local function setCursorPos(x,y)
  mn.setCursorPos(x,y)
  mnb.setCursorPos(x,y)
end
local function setBackgroundColor(clr)
  mn.setBackgroundColor(clr)
  mnb.setBackgroundColor(clr)
end
local function write(txt)
  mn.write(txt)
  mnb.write(txt)
end
local light = false
while (true) do
  local senderId, message, protocol = rednet.receive()
  if (message == "light") then
    if (light == false) then
      light = true
      for i=1,sx do
        setCursorPos(i,2)
        setBackgroundColor(colors.yellow)
        write(" ")
      end
    else
      light = false
    end
  end
end