| As a major industrial manufacture device, the high-grade CNC machine tool can meet the reqirements such as high-speed and high-precision machining, as well as multi-channal and multi-axis control. It is important to build a high-speed data transmission channal between NC and PC.The aim of the CNC system designed in this thesis is to ensure that the comunication between computer and servo unit can meet the requirements of real-time and reliability. The design is applied to industrial ethernet bus communication module of CNC system. Industrial ethernet dirver for the host computer of CNC system is developed. Diver provided API interface for the bus control program and data transaction to achieve high-speed reliable communications. In order to improve the bus real-time performance, RTX (Real-Time Extension) software is used to provide windows-compatible hard real-time environment. Industrial Ethernet real-time universal driver program is researched and given the realization of real-time API methods for industrial ethernet, developed driver with Windows Driver Model (WDM) driver standard which achieved CNC system high stability and real-time communication requirements.The thesis firstly makes a deep study of ethernet standards, including the system architecture of industrial ethernet, the hierarchical structure of the ethernet protocol and communication modal of ethernet,especially in TCP/IP protocol. Industrial ethernet communication module for CNC system is designed. Then the RTX real time enviroment is analyzed in terms of principle, characteristics and application. RTX, as a subsystem for the Windows system, provides a kernel-mode execution environment for Win32 compatible tasks and threads that have hard real-time performance characteristics. In addition, the industrial ethernet communication module of the CNC system is explicated. The PCI-ethernet interface card is used to act as the interface of host computer, and the ethernet front-end module designed specially is used to act as the interface of servo units. The whole process of communication is explicated, and the usage of API functions provided by RTX is given. During the process of the software design, the program is modularized according to the requirement of software engineering, and in consequence it improves the efficiency of program and makes the structure of program clearer. Finally, the software which implements the data transmission between host computer and Ethernet front-end module is tested. Large numbers of experimental data are analyzed to verify that the system is enough reliable and real-time to meet the requirements of a high-grade CNC system.
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