Implementation Of Diagnostic System Based On Auto Fault Code

With the rapid development of the automotive industry, car ownership is growing, the electronic control technology has been widely used in the automotive industry, which increased the power and economy of modern cars, but also increased the difficulty of diagnosis and repairment. In order to adapt to the development of high-tech car, it is necessary to set up a modern car fault diagnosis system in order to avoid the experience of traditional diagnostic methods in the diagnostic accuracy, efficiency and ease of use on the problems encountered. This system which starts from the demand of Jiefang Company's after service station, has established diagnose system based on auto fault code to suit for the station's concrete situation. This system make maintenance men be divorced from traditional way of maintenance based on manual experience, which not only raises the efficiency and the accuracy of fault diagnose,but also provide new technique measures for the after service station. The application of this system greatly enhance the quality of the station's service, and make the working of the after service step in a new stage.Firstly, this thesis expatiate about the exploitation background and the research actuality of the diagnose system based on auto fault code, expatiate on the instancy, necessity and feasibility of the diagnose system; secondly, the thesis expound about the primary study content , then according to the software exploitation method in the software engineering ,it accomplish the requirement analysis ,the general design and the detailed design of the system and so on .thirdly, it simply introduce the tools such as Visual C++ 6.0 and SQL Server 2000 which are used in the exploitation of the system. Besides, it also introduce the ADO tech which is very popular in Microsoft's high floor data-base accession. Finally, it researches and discusses the key tech using in the process of designing system, such as the algorithm of data encryption and decryption, SQL statement explicitly convert ciphertext, and database encryption ,etc.After service station is the very important part of the auto sell, and it is the precondition for the survival and development of the auto sell. Combined with the work of after-sales service stations, this thesis proposes the the system's functional requirements, database needs and security needs. Because at the early stages of system design, maintenance personnel has only one preliminary ideas, can not fully express the system requirements, moreover, in the development process, it will continue to generate new demand, so the system uses a rapid prototyping method of development. On the basis of the in-depth investigation of the after service station and the repairment data , this article identifies the ideas of developing the system. Setting up and maintenancing databases as well as the front-end application development are the most important.After-sales service station's main task is to determine the location of vehicle breakdown. Maintenance personnel read automotive code though the diagnostic equipment , and according to the detection steps which is corresponding to the fault code, detect the automotive to determine the fault location. Then, according to the disassembly steps in maintenance handbook, the maintenance personnel replaces the parts which are broken. Finally, they check the parts which have been installed to ensure the vehicle can operate normally. As the requirement of the diagnostic system based on automotive fault code, the data of fault diagnosis and repairment are both deposited in the database.As a subsystem of the Jiefang Company, the diagnostic system which is based on fault code integrates auto diagnostic theory and empirical knowledge, uses systematic knowledge and theory, analogs the repairman's process of maintenance to guide the repairment and help them exclude fault duly. The diagnostic system is consisted of fault diagnosis, replacement of parts guidance, later check, query search, data encryption and decryption etc. According to users'different needs, these sub-functions finishes different tasks. Various functions required to read different data from the database, and, when it is necessary to update data, update the database. After confirming the need analysis, the paper begin to design system. Firstly, the article describes the network structure of the system, the components of the system and software architecture; secondly, the article introduces the instrument of front-end development and management system selection of back-end database. Then, the article begin to design the database. The database is mainly used to store diagnostic data and maintenance data. These data can give a hand to help repairman find the location of the fault by the fault code, replace broken parts and check the parts after replacement. In the paper, the design of database and system are combined. The system can performance data clearly, and at the same time the system can easily access and update data. Application Module Design determines the system's main modules and sub-modules, and describes their function, operation strategy, module flow chart etc.In the phase of the system's coding and enablement, the paper expounded the technology of database access in detail. ADO is a high-level database access technology. Based on the Common Object Model, it simplifies the operation of OLE DB. The system packages the operations of accessing the database through ADO, and it make the access to the database be more flexible and more convenient. At the same time, this article introduces ADODriver, which is ADO's packaging object. ADODriver packages the operations which are commonly used in ADO. And after package, it is convenient to add, delete, change or check the data in the database, which greatly improve the efficiency of the system.Finally, the article discusses the Base64 encryption and decryption algorithm as well as database encryption in detail. First of all, the system used the Base64 algorithm to encrypt the database, to form ciphertext database. Base64 is a way of encoding data,has the function of encryption.The article elaborates the birth of the key of the Base64 encryption and decryption algorithm as well as describes the algorithm of encryption and decryption. At the same time, it also discusses how to encrypt and decrypt database by the Base64 encryption and decryption algorithm. Then, it simply introduces how to enable the conversion between plaintext and Ciphertext for the SQL statement, to support the system to access the Ciphertext database. Finally, it describes the interface after the system's enablement.The diagnostic system based on Automotive Fault Code meets the requirement of the After service workstation, and the system has maintainability and expansibility. Each functional module of the system can actualize its function independently. And they can be assembled and collocated. In addition, the system has expansibility. So when new module is added, it can connect with the original system seamlessly, then realize the original system's function of expansibility.