Research On Technologies Of Real-Time And Wideband Field Network

Fieldbus Control System (FCS) is a typical distributed real-time control system for industrial applications. Fieldbus is the core and important part of FCS and its timeliness and reliability are keys to ensure the effective implementation of the functions of FCS. With the rapid development and wide application of FCS, the shortcomings of traditional fieldbus are gradually exposed, such as speed, openness, performance-to-cost ratio and so on. Therefore, it is very crucial for us to design a novel wideband communication technology of fieldbus, which not only have good timeliness, reliability and performance-to-cost ratio, but also support the integrative building of networks and information. In order to resolve those problems, we have made researches on both theory and practice in this dissertation. As a result, some valuable fruits are achieved and contributed to high reliable real-time network.Firstly, distributed real-time computer system is discussed in depth. The architecture, characteristic and timing constraint of distributed real-time systems are analyzed. As a conclusion, we think the main obstacle of developing a highly dependable real-time system is to guarantee timing constraint of end-to-end. Further more, the communication architecture of distributed real-time system and the basic implementation technologies of real-time LAN are researched. The implementation approaches and working modes of real-time fault tolerance technology are analyzed in details. In addition, some real-time scheduling theories and functions of real-time operating system are introduced. As a result, it will be facilitative to research and develop novel distributed real-time system and highly reliable real-time communication network.Based on works above, the requirements of field control network in FCS are researched and the limitations of existing fieldbus technologies are analyzed. In addition, the necessity of using Ethernet to design next-generation FCS is analyzed in details. At the same time, we indicate that the crucial obstacles of developing fieldbus domain based on Ethernet are timeliness and reliability. Some approaches used to improve the timeliness of Ethernet are also researched. Then, four main problems are researched in this thesis, including:1) The architecture of Ethernet used to fieldbus: On the basis of requirements of FCS system, the architecture of Ethernet used to fieldbus in FCS, network architecture of field Ethernet, protocol framework and so on are discussed in this thesis. As a result, a novel real-time architecture of field control network based on Ethernet, named ARTCA, is proposed. ARTCA can efficiently integrate Ethernet into fieldbus control domain via master/slave way without modifying hardware of Ethernet. ARTCA can realize integrative management and control with low complexity because of its compact system architecture and novel protocol architecture. At the same time, protocols and functions based on ARTCA are analyzed and designed in details, and the link technology of fieldbus devices is also researched in details.2) The reliable safeguard techniques of field Ethernet: The network architecture used to design highly reliable field control network is analyzed in details, in addition to design goals, principles, system model of fault tolerance network. As a result, a redundant network is proposed to guarantee reliability of ARTCA. Correspondingly, based on redundancy theory, many techniques including system management, fault diagnoses and disposal are researched. Real-time communication can be reliably implemented with the reliable architecture of ARTCA even if there exist some hardware or software faults. At last, the embedded design technique of double redundant network is researched.3) The real-time scheduling mechanisms of field network: Firstly, the uniprocessor tasks-scheduling algorithms are discussed. Then, a hard real-time scheduling approach is proposed to schedule messages in field control network after analyzing the requirements and characteristics of field network. At t...