MODBUS协议及freemodbus的实现源码。适合应用于单片机/arm与触摸屏或者其他工控设备的通讯（绝大多数触摸屏都支持modbus协议）。(The MODBUS protocol and the source code for the implementation of freemodbus. It is suitable for the communication between single chip /arm and touch screen or other industrial