Study On Digital Interface Technology Of NC System Based On Ethernet

The networked, digital and opening tendency of the NC system requires cheaper, more open and stable digital interface network to connect between NC system and all executing module. Ethernet is the factual standards of the commercial network. With its mature technique, good opening, compatibility and low cost, the Ethernet is likely to become the standard of such digital interface. But still there is a great deal of problems to be solved. This dissertation makes deep research on the application of Ethernet in NC system digital interface. The synchronicity, real-time, reliability and relevant protocol are mainly concerned in this paper.This dissertation analyses the traditional architecture for Ethernet-based NC system difficulties, and analysis of the Ethernet-based NC system architecture requirements. Based on the features of the Ethernet-based NC system, this dissertation puts forward a hiberarchy basing on the characteristics of the level . The hardware of this architecture based on more processor, is of amalgamation and reconstruction, the software is based on muti-operation system, the interface adopts Ethernet.This dissertation analyses the Ethernet interface system clock synchronization. According to different level requirement of Ethernet-based NC system , this dissertation puts forward a method of mixed clock synchronization basing on the characteristics of the level . It through PLL to get the hardware clock synchronization, through Barker Code to achive timestamp in the MAC layer, through the characteristics of precision-scale adjustment cycle synchronization.And the effectiveness of this method is testified by experiments.This dissertation analyses the Ethernet random access mechanism leading to the real-time problems. Analysis of Various access mechanisms for the advantages and disadvantages.And puts forward a Real-time guarantee methods of inclusive CSMA/CD, that is to maintain the integrity of the Ethernet, and to avoid a collision, Thus improve the system's real-time. Experimental verification of the proposed method.Because of the resending mechanism in Ethernet. Ethernet used in NC digital interface have great difficulty. Based on the features of the Ethernet-based NC system, This dissertation combines organically the hardware redundancy, software redundancy, time redundancy and Forward Error Correction, and puts forward a multi-level multi-mechanism reliability guarantee method. The experiment has testified that it can great improve the communication reliability without influencing its real-time capability.This dissertation basing on the different Topology structure, combination synchronization, real-time capability, and reliability guarantee technology design star protocol, and ring protocol and also analyze the advantage and disadvantage of these two protocol.Basing on the reseaches made in previous chapter, the dissertation also develops the prototype sample machine of Ethernet-based NC system.