从网口接收数据，发送到com口，从com口接收数据发送到网口，使用了对串口操作、多线程、socket编程等技巧。有makefile和测试程序-Receiving data from the network port to send to the com port, receive data from the com port to send to a network port, use the serial operation, multi-threading, socket programming skills. Makefile and test procedures