VISA Engine And Common Interface Drivers For Universal Test Instrument

Virtual instrument technology brings automatic test field with technologicalinnovation, which makes software development for instruments more and moreimportant. VISA (Virtual Instrument Software Architecture) is an advanced API forcommunication between users and instruments with different bus interface. It is widelyused for interaction between test instruments and the upper computer as the connectionof software layer in measuring industry.As the I/O interface software, VISA packages all operation of instruments’hardware interface. It publishes its operational interface function prototype. The VISAis independent of the specific interface bus of instruments, type of instruments,operating system of computer and programming language. The dissertation developsvirtual instrument software architecture for general test instrument with independentintellectual property rights. The main contents as follows:(1) The design of overall structure for VISA. With the core of layered architectureand design pattern, the overall structure was designed. The layered structure organizedVISA system according to different function duties to realize high cohesion and lowcoupling and improve the efficiency and maintainability of software system.(2) The design of detailed parts of VISA was accomplished, including attributeimplementation, the resource manager and resource parser. The resource managementwhich manages resource with chain table was completed and realized to achievebackward compatibility for VISA library. The resource parser was designed with threeparts: lexical analysis, syntax analysis and regular matching. Each module collaboratedand implemented efficient and accurate parsing.(3) The design of driver for various types of interface. With the thought ofseparation of mechanism and policy, each type of I/O interface driver was designedrespectively, as message-Based or Registered-Based, including PCI interface driver,Ethernet interface driver and local bus interface driver. (4) Software testing. According to the different function of modules, the testingplan was designed. Then test for each module was done respectively. Then combinedwith the overall framework of VISA, the whole test was completed. Last problems intesting were analyzed and solved.According to the test result, the VISA supports multi-platform, re-entrant,multi-language and multithreading safety.