Draconic crafting automation (2 turtles - second turtle)

--[[
down - injector
--]]

local turtle_id = 13

-----------------

rednet.open("left")

while true do
    local id, msg = rednet.receive()

    if id == turtle_id then
        local error = ""

        if msg == "RETRIEVE" then
            print("Processed command to retrieve item")
            turtle.suckDown()
        else
            for i=1,16 do
                local slot = turtle.getItemDetail(i)
                if slot and slot.name == msg.name and slot.damage == msg.damage then
                    print("Processed command to send item: " .. msg.name .. "/" .. msg.damage)
                    turtle.select(i)
                    turtle.dropDown()
                    break
                elseif i == 16 then
                    print("Item not found: " .. msg.name .. "/" .. msg.damage)
                    error = msg.name .. "/" .. msg.damage .. " not found"
                end
            end
        end

        if error ~= "" then
            rednet.send(id, error)
        else
            rednet.send(id, "DONE")
        end
    end
end