The Reliability Technology Research Of PROFIBUS-DP Control System

Reliability is one of the most essential characteristics of automatic control systems. With the increasing complexity of automatic control systems and the ever-higher reliability required by more and more applications, a sound reliability has become one of the main design goals of control systems. It is therefore necessary and particularly important to make a study on the unreliability of control systems and advance the corresponding solutions. After analysis and comparison, PROFIBUS-DP, a promising fieldbus control system that has been widely used, is chosen as the research subject. Based on the analysis of the unreliability of PROFIBUS-DP, various methods to improve the reliability of it have been given.In chapters 2 and 3, an introduction of the architecture of PROFIBUS including its protocol structure and the three compatible composing elements DP, PA and FMS, is given. Based on this, we delve further into the system architecture, system behavior and system configuration of PROFIBUS-DP. Its transfer techniques, media access control methods, data transfer services and address assigning mechanism are introduced, while their characteristics are also analyzed.After developing a sound understanding of the structure and key techniques of PROFIBUS-DP, we begin to analyze its reliability. In chapter 4, we first analyze the fault, the root that causes the unreliability of the system. The main faults of PROFIBUS-DP are categorized and studied. The phenomena and causes of the faults, together with the measurements for recovery and masking, are discussed in detail. Then, through the analysis of the chain from the fault occurrence to system failure, a strategy that advances the system reliability in response to the different phases of the process during which the faults cause the system failure is given. The thesis studies the effective measurements to improve the reliability of PROFIBUS-DP through fault prevention and, especially, fault tolerant. Through analysis, a strategy to improve the tolerance that involves protocol mechanism, redundancy and fail-safe technology is advanced.During the study on the measurements to improve the system reliability, abundance is examined especially carefully, considering its particular importance to system reliability. It also consists the key subject of the present thesis. In chapter 6, we first provide a theory background of abundance. We later move on to the three aspects of the abundant system of PROFIBUS-DP, i.e. master redundancy, slave redundancy and line redundancy. This involves the definitions, architectures, functioning mechanisms of the three aspects. The respective functions of each are analyzed in detail.After the close study of the three aspects and the key network components for implementation, we are on the way to the realization. In chapter 7, using the conclusions drawn before, we introduce three different architectures of the abundant system of PROFIBUS-DP, together with their working mechanisms and their respective functions.Thus, we have developed a set of measurements to improve the reliability of PROFIBUS-DP. Using the results of the study, the reliability of PROFIBUS-DP can be greatly improved, which means that the results have some real applications. Also, the study will also help the improvement of PROFIBUS-DP.