Door Server

local GEARSHIFT  = "black"
local MODEM_SIDE = "top"

rednet.open(MODEM_SIDE)

local function main()
    local id, message = rednet.receive();

    if type(message) == "table" then
        if message[1] == "door" then
            if message[2] == true then
                redstone.setOutput("back",  true)
            elseif message[2] == false then
                redstone.setOutput("back", false)
            end
        end
    end
    main()
end

main()