Test Studies, The Test System, Distributed Database And Network Communication Mechanism

With the lasting raising of war industry product's complex and modern level, It relies on advanced experiment and test means increasingly to design, develop and maintain war industry product's system. And now, with the development of network technology, database technology and distributed calculate theory becoming perfect day by day, It is the good condition to develop Integrated Virtual Experiment and Measurement Technology.Incorporated with the tenth -five project ?IVEMT" of the Commission of Science Technology and Industry for National Defence, Key technology of distributed database and network communication in Experiment & Measurement System, is studied thoroughly in this thesis.The paper studies network and database technology about dataflow,in clue of a elementary course from data acquisition,data disposal,data being dumped database,to data being transmitted in Distributed Experiment & Measurement System(DEMS).In view of characteristics that LabWindows/CVI development kit sustains real_time communication, real_time control , perfect data disposal and data analysis abilities of Experiment & Measurement System, data acquisition,data disposal,data display and data file storage of the measured object are finished by LabWindows/CVI, and LabWindows/CVI development module is used in Visual C++ development environement.After analyzed and compared characteristic of several common interface programs of database, MFC ODBC interface of accessing database being abundant functions and operating easily,the thesis studies thoroughly the mechanism that MFC ODBC is used to visit database. Considering diversity of data formats in DEMS, file and source database transforming target database are sloved by MFCODBC.Real_time requirement and time sequence consistency are important symbols in DEMS, the paper analyses thoroughly factors that system real_time is restricted, and merits that main memory is used as a storage medium. In order to satisfy system real_time and openness, distributed database in Experiment & MeasurementSystem unites Real_time Main Memory Database and SQL Server 2000. The paper discusses the time sequence consistency in DEMS and introduces the concept of absolute time sequence consistency and relative time sequence consistency. This paper suggests that in DEMS, priority levels be used to solve the problem of absolute time sequence consistency and data view be used to solve the problem of relative time sequence consistency. System time synchronization becomes a serious problem in large DEMS, This paper studies time synchronization technology, considering system expansibility and high precise time synchronization, and suggests that a design thinking of NTP solves time synchronization in DEMS.The actual use and theory analysis indicate that LabWindows/CVI development kit can enhance perfectly system real time measurement and control abilities; detailed data formats can be transformed easily target database by MFC ODBC; Real_time Main Memory Database directly accessing main memory is a perfect scheme to meet the real time requirement; priority levels and data view that are designed on system characteristics, can solve primely the problem of time sequence consistency; NTP can basically meet system time synchronization requirement.