Scanner

function open(chan)
  local OK=false
  for n,sSide in ipairs( rs.getSides() ) do
    if peripheral.getType( sSide )=='modem' then
      write("Modem at "..sSide.." side. Channels from "..chan)
      for i=1,128 do
        peripheral.call( sSide, "open", chan )
        chan=chan+1
      end
      print(" to "..chan-1)
      OK=true
    end
  end
  if not OK then print("No modem was found") end
  return OK
end

function wLine(Text)
  f = fs.open("log",fs.exists("log") and "a" or "w")
  f.writeLine(Text)
  f.close()
end

Arg={...}
start=tonumber(Arg[1]) or 0
if open(start) then
  while true do
--    sEvent, sChannel, sMessage = os.pullEvent( "rednet_message" )
    sEvent, sModem, nChannel, nReplyChannel, tMessage  = os.pullEvent("modem_message")
    print("From ", nChannel, " ", tMessage.message)
    wLine("From "..nChannel.." "..tMessage.message)
  end
end