mobKiller.lua

local time = 30
local rsSide = "top"

-- below does not matter, auto-detected.
local esSide = ""

local function switch()
  rs.setOutput(rsSide, true)
  os.sleep(0.5)
  rs.setOutput(rsSide, false)
  os.sleep(0.5)
end

local function canRunEntitySensor()
  for i, periph in ipairs(peripheral.getNames()) do
    if peripheral.getType(periph) == "manipulator" then
      esSide = periph
      if peripheral.call(esSide, "hasModule", "plethora:sensor") then
        return true
      end
    end
  end
  return false
end

local function check()
  local ents = peripheral.call(esSide, "sense")
  for i, entity in ipairs(ents) do
    if entity.x > 0 and entity.x < 2 and entity.z > 0 and entity.z < 2 then
      return true
    end
  end
  return false
end


local function main()
  local entityCheck = canRunEntitySensor()
  while true do
    if entityCheck then
      print("Checking entities...")
      if check() then
        print("Shooting.")
        switch()
        print("Done.")
      end
      os.sleep(3)
    else
      print("Shooting.")
      switch()
      print("Done. Waiting 30 seconds.")
      os.sleep(30)
    end
  end
end

main()