public void SelectMill(int millId)
        {
            var msg = string.Format("Please insert mill #{0}", millId);

            machine.Pause();
            Dictionary <string, string> message = new Dictionary <string, string>
            {
                ["type"]         = "message",
                ["message"]      = msg,
                ["message_type"] = "tool change",
            };

            router.Message(message);
        }