中文摘要：

针对以太网通信、串口通信和总线通信在上下位机模式的数控系统中的应用，分析了上下位机之间通信的功能需求，提出了合理的通信模式和通信层次结构。通信模式采用的是客户端／服务器模式。客户端和服务器都包括通信引擎层、通信抽象层、通信接口层／通信服务层。通过对通信服务层中的变量服务、命令服务、报警服务以及文件服务分别进行分析，提出了每一种服务相应的设计方案。最后，通信模块的测试结果表明该通信模型既可以采用不同的通信介质通信，又可以实现不同平台间的通信。

英文摘要：

With regard to the application of Ethernet communication,serial communication and bus communication between the master computer and the slave computer in CNC system, the paper ana- lyzed the functional requirements,poposed a reasonable communication mode and communication hier- archy. The communication mode was client/server mode. Both of client and server contained communi- cation engine layer, communication abstraction layer, communication interface layer/communication service layer. Through the analysis to variable service, command service, alarm service and file service of communication service layer,this paper put forward the design of every kind of service. Finally,the results of the communication module test indicate that communication model can communicate through different communication media, and communicate between different platforms.