CC Mek Reactor On/Off

local monitor = peripheral.find("monitor")
local modem = peripheral.find("modem") or error("No modem attached", 0)
local status = -1 -- -1 - null 0 - Off 1 - On

modem.open(1)

while true do
    local event, side, channel, replyChannel, message, distance
    repeat
        event, side, channel, replyChannel, message, distance = os.pullEvent("modem_message")
    until channel == 1

    if status == -1 or (message < 0.5 and status == 0) then
        redstone.setOutput("back", true) -- Redstone on
        status = 1
        print("Reactor On")
    elseif status == -1 or (message > 0.8 and status == 1) then
        redstone.setOutput("back", false) -- Redstone off
        status = 0
        print("Reactor Off")
    end

end