Reasearch And Development On Auto Test System For MODBUS Protocol

Fieldbus is one of the hotest spots in the developping of automation field nowadays. Especially for Modbus protocol, because of its perfect functionality, easy useness and full openness, it has got support from most IED (intelligent electrical device) companies. Testing for MODBUS protocol is always an important procedure during IED development. However, due to limitation of test period, protocol testing is becoming a bottle-neck for development of MODBUS function of IED.Based on deep research on the principle for MODBUS protocol conformance test and auto test theory, combined with professional work experience, this paper proposes combination of protocol test and auto test, and develops the corresponding auto test system for MODBUS protocol accordingly. Consequently, the system raises the efficiency for testing; shorten the cycle for IED development.First, the Modbus protocol specification is described. This chapter expatiate the corresponding theory, including software testing, protocol testing, auto test theory and system and so on. It explains protocol testing issue attributes to software testing, introduces the main content for protocol testing, expounds the necessity for protocol testing and test automation and provides the theory base for research and development on auto test system for Modbus protocol in the following chapters.Second, this chapter brings forward a test automation method for combination of protocol testing and auto test based on research on the principle of Modbus conformance test and FDT (Formal Description Technology). This method realizes the auto execution for test procedure and auto analysis for test result, which is the innovation point of this paper.Third, this chapter develops the auto test system for Modbus protocol, which mainly implements the auto test for IEDs that supports MODBUS protocol. This paper describes design and implementation of the system which composed of hardware environment and test software. The design of hardware environment constructs a test platform, which sets up a Client/Server system. As the central component of test system, test softsware is on the basis of Win32 application. After making reserch for windows serial communications, it focuses on the design and implementation of software modules and provides flow chart and source code for each software module.Finally, some experiments have been made for the constructed test system. After running the test software, this system is proven to meet all the design requirements.