此程序用UART1外扩MAX485实现RS-485通信，运行前将TX1和P00 短接，RX1和P01短接，当接收到一个数据后，再将接收到的数据送出。-Expand this program in use UART1 MAX485 RS-485 communication, running before the TX1 and P00 short, short RX1 and P01, then the received data when the receiver to a data send.

自己写的RS485的通讯程序，调试通过的，可以作为初学者的入门程序。-Write your own RS485 communication program, through debugging, as a beginner entry procedures.