可以侦听最多两个串口的数据， 主要是为了调试通讯设备使用， 尤其是各种modem, 因为内置了cmux解析功能， 非常方便阅读。-Can listen for up to two serial data communication equipment mainly used for debugging, especially the variety of modem, because the built-cmux parsing, very easy to read.