资料来源 : pyDict

数据终端准备好,(指RS-232C的第20脚,在DTE已加电并已准备好时为HI,用来通知计算机可以发送数据)

资料来源 : Free On-Line Dictionary of Computing

Data Terminal Ready
     
         (DTR) The wire in a full {RS-232} connection
        that tells the {Data Communication Equipment} (DCE, typically
        a {modem}) that the {Data Terminal Equipment} (DTE, typically
        a computer or {terminal}) is ready to transmit and receive
        data.
     
        (2000-04-05)