Virtual DPU Development Based On IEC61131-3Standard

Virtual DPU based on IEC61131-3standard is a general open simulation technology to realize the virtual DCS, which can mirror the real hardware and software functions of DPU. This paper uses the object-oriented analysis method to analyse IEC61131-3standard, and abstracts logic elements contained in software model to an object model. Object model contains the configuration object, resource object, task object, program object, program organization unit, according to the definition of standard about each object function to determine the object properties and methods of classes, as well as the logic relation between objects. According to the function of the object boundary to form logical mapping between object model and DPU structure, configuration corresponds to the DPU element, resource corresponding to the DPU main control unit, tasks and procedures corresponding to main control unit operation control program. This logic mapping as the basis for virtual DPU design, design types for each object using the object oriented design method. To realize virtual DPU function through cooperation between classes.Virtual DPU’s tasks includ the reproduction of real DPU control function and the realization of virtual DCS communication. Reproduction of the real DPU control function has to obtain configuration information of DPU, the control configuration information of real DPU is from configuration file configured in engineer station of DCS. Virtual DPU control configuration information is from the configuration file configured in engineer station as well. XML format for IEC61131-3standard supportted by PLCopen standard provides technical support for virtual DPU to obtain control configuration information without difference. Information transmission between development environment and simulation platform is an important case provided XML format for IEC61131-3standard. Engineer station of virtual DCS packages configuration file through particular XML format for IEC61131-3standard, then transmit XML document to virtual DPU.Virtual DPU extract the configuration control information through analyzing XML document. Virtual DPU guidances the cooperation of objects to reproduce DPU control function. The bridge of data communication between virtual DPU and HMI is OPC data access server. virtual DPU acts as data source of OPC server. Data communication between OPC server and virtual DPU is based on shared memory technology.