The server then initializes a connection back to the client to open the data port. 然后服务器初始化到客户端的连接以打开数据端口。
Thus the data communication monitor sends its own polling signal to the front-end device's next port is polled. 因此，数据通信监近程序就发送自己的查询信号，事实上是询问前端处理机数据是否已在给定数据端口的缓冲寄存器内。
