Ganing

you should set a timeout when open the port ```go err = serv.ListenRTU(&serial.Config{ Address: addr, BaudRate: cfg.Rtu.BaudRate, DataBits: 8, StopBits: 1, Parity: cfg.Rtu.Parity, Timeout: time.Duration(cfg.Rtu.Timeout) * time.Millisecond}) ```