Design And Development Of Automatic Test System Of A Kind Of DCS System I/O Modules

DCS is the abbreviation of distributed control system. Distributed control systemoriginated in the last century seventy’s, is compared with the centralized control system. TheDCS system integrates "4C" technology,which include Computer technology, Communicationtechnology, display technology(CRT) and Control technology. The basic target of distributedcontrol system is centralized operation and Classification management, system can beconfigured flexible,maintenance easy and high reliability.DCS system is besed in communication network, with computer and automationinstrumentation as implement.DCS can perform reporting statistics, alarm display, faultdiagnosis, remote control and other functions in production process to achieve industrialautomation monitoring and control.The DCS system is wide used in electric power,metallurgical, chemical, paper and other important economic fields, in order to improveproduction efficiency, reduce labor intensity and improve working environment.The I/O module in DCS system is used to connect the DCS controller and the electricaldevices. On one hand, the I/O module will be responsible for the controller instructions areconverted to the digital or analog signals that electrical device can identify, and then driviethe electric device to make a correct response; on the other hand, the I/O module can bedetected electrical equipment working state in real time, the collected data would be reportedto the controller, so that the workstation software can make a correct judgment for measuring system working state. It can be said that the I/O moduleIs in a DCS is the bridge and link ofsystem controller and electrical device.its working condition directly affects the performanceof the DCS system. Therefore, in the DCS system production and installation process, the I/Omodule testing is very important.This project takes "HPCS system" as the foundation,which is the DCS system of someCompany. This article analyzes a DSC I/O module automatic test platform. The automatedtesting platform is make up of CardDebug procedures and USB-RS485conversionmodule.CardDebug procedures is running on the Windows operating system, andUSB-RS485is with responsibility for computer and module of I/O protocol conversion.CardDebug program encapsulates most Modbus protocol details, can provide users with afriendly, visual operation interface. Program make checker of I/O modules can get rid ofcommand line using in serial port, with the operation of the mouse to complete the basic test.At the same time, CardDebug program also retained the custom Modbus command sendingfunction, for the checker to provide enough flexibility and scalability. Through USB to RS485interface card conversion and adaptation, Any computer as long as the computer can haveUSB interface can implement I/O module’s debugging and configuration. This makes theautomation test programs can implement in a variety of hardware platforms.This paper describes development process based on Visual C++CardDebug applicationin detail, about the Modbus protocol, serial port communication based on the VC and thethreading operation and timer settings and other core processes in-depth summary; In USB toRS485interface card design,a detailed description of development process and key technicalpoints based on FT232B chip of FTDI is given.This automation test platform has been applied in the DCS system I/O moduleproduction, testing, delivery chain, It improved the HPCS system I/O module testeffectively,and is an important process to ensure the reliability of HPCS system. This topic’sviewpoint and the realization of the project has certain reference significance and practicalvalue on a similar system of automated testing.