DMAVR-L的RS485通信示例程序，采用串口1，发送采用查询方式，接收采用中断的方式

通过串口调试助手将16进制数据发送到系统板，系统板再发回电脑，在串口调试助手中显示出来-DMAVR-l RS485 communication example program, use the serial port 1, and send the query, receive adopt the way of interruption

Via a serial port debugging assistant will hexadecimal data sent to the system board and system board again back to computer, displayed in the serial debugging assistant