slime.lua

local modem = peripheral.wrap("top")

while true do
    local power = rs.getAnalogInput("back")
    if power > 13 then
        print("over")
        modem.transmit(50, 51, 1)
    else
        print("under")
        modem.transmit(50, 51, 0)
    end

    print(power)
    sleep(2)
end