说明：  MODBUS协议实现一主机对多从机轮询的示例。在工装设计之前做了这么一个仿真示例，展示主机与从机之间应用简易的MODBUS 04命令进行轮询会话的过程。PROTEUS设计中有标示，程序中代码有注释，希望能对需要的朋友有所帮助。
(MODBUS protocol of a host of many examples of polling from the machine. Done before the tooling design such a simulation example that shows the host and slave MODBUS 04 between the application of simple commands during the polling session. PROTEUS design, marked, there are comments in the code, hoping to help a friend in need.)