modem.lua

local modem = require("component").modem
local event = require("event")
local keyboard = require("keyboard")
local term = require("term")

local run = true
local message = ""

modem.open(123)

if modem.isOpen(123) then
  print("Open!")
else
  print("Sorry")
end

function mod (_,_, sender, port, distance, msg)
  print("[Port: " .. port .. " Distance: " .. distance .. "] " .. msg)
  if msg == "stop" then
    run = false
  end
end

function k_d (_,_, char, code)
  term.clear()
  local key = keyboard.keys[code]
  if key == "enter" then
    modem.broadcast(123, message)
    message = ""
  elseif key == "space" then
    message = message .. " "
  elseif key == "back" then
    message = ""
  elseif key == "f1" then
    run = false
  else
    message = message .. key
    print(message)
  end
end

event.listen("key_down", k_d)
event.listen("modem_message", mod)

while run do
  os.sleep(0.1)
end

event.ignore("key_down", k_d)
event.ignore("modem_message", mod)

os.exit()