An MDD Process for IEC based Industrial Automation Systems

Transcription

1 An MDD Process for IEC based Industrial Automation Systems Kleanthis Thramboulidis Member, IEEE Electrical & Computer Engineering University of Patras, Greece Geog Frey, Senior Member, IEEE Chair of Automation, Saarland University, Saarbrucken, Germany SS07: Distributed Automation Systems Development: Trends and challenges 16th IEEE Conference on Emerging Technologies and Factory Automation, September 5-9, Toulouse, France. The traditional development process P&I Diagrams Design of control application Library of reusable Modules (PLCopen XML specification) FB types PLCOpen XML Specification of the control application Generate target platform executable PIM Run-time Application s Execution model PSM based execution environment K.Thramboulidis ETFA

2 The proposed approach exploits MDD we claim that 1131 FBD has already introduced the MDD process in Industrial Automation is based on the OO view point of 1131 we claim that 1131 adopts main concepts of OO adopts IEC (CAEX data transfer lang.) as a source of PCE requirements K.Thramboulidis ETFA Outline IEC revisited as a Model Driven Development process as an OO programming model Alternatives for a more effective 1131 development process The SysML-based proposed approach Concluding remarks K.Thramboulidis ETFA

3 IEC as MDD MDD key concept models have become primary artifacts of software design, shifting much of the focus away from program code. IEC the Function Block Diagram (FBD) graphical programming language characterizes the development process as model driven what is all this research about defining MDD approaches based on IEC 61131, in the industrial automation domain? K.Thramboulidis ETFA IEC as MDD: disadvantages Only one kind of diagram captures FB instances and their interconnections is used to specify the structure and behavior of programs or FBs Structure and behavior in UML and SysML several diagrams are used One diagram, the FBD, is not enough to effectively construct an expressive model K.Thramboulidis ETFA

4 IEC as MDD: Challenges Reduce the gap between PCE requirements and the FBD design model use more diagrams to construct more abstract design models Increase the completeness and comprehensibility of the models use extra diagrams to capture more aspects of the system K.Thramboulidis ETFA The OO point of view: The FB IEC has already introduced a few basic concepts of the OO paradigm, in the automation domain. Defines the structure and behavior of a collection of objects graphical representation > UML class construct textual representation > C++ class construct it may be considered as a special kind of class with several restrictions but also extensions. K.Thramboulidis ETFA

5 1131-The OO point of view: The FB Behavior Only one method can be defined. usually captures all the different behaviors exhibited by the FB instance in response to the various messages an instance receives from the environment. there is no method signature. method is executed when the FB instance is called. specification of the method can be given either in textual or in graphical notation (one or more FBNs can be used in this case) SFC is more convenient in the case that the FB implements a state machine. K.Thramboulidis ETFA The OO point of view: The FBN It can be considered as structural specification diagram is used (according to the standard) to capture behavior (like activity or collaboration diagram) but with lower level of abstraction and well defined execution semantics It is analogous to the abstract syntax tree generated by a C compiler Message passing: no method call K.Thramboulidis ETFA

6 Towards a more effective development process The need for more diagrams and higher levels of abstraction in application modeling Possible alternatives the IEC function block model, the UML, and the systems modeling language SysML. K.Thramboulidis ETFA Using IEC Dynamic behavior IEC ECC <-> SFC in IEC FB Algorithms independent distinct algorithms -> to a more modular FB body, but since there is no support for inheritance there are no direct benefits regarding reusability. FBN does not provide a better way to capture the behavior of the application. No support for higher layers of abstraction. K.Thramboulidis ETFA

7 Using UML A specific UML class represents the FB. UML diagrams to create more abstract models composite diagram: structure of programs and FBs. state diagram: the behavior of programs and FBs. sequence and/or activity diagrams: behavior in terms of interactions between FB instances, and to model the behavior of an enclosing FB. class diagram: structure of the PLC infrastructure. deployment diagram: graphical representation of a configuration. K.Thramboulidis ETFA Using SysML Suports OO and procedural approach SysML block to model not only the FB but also the function and configuration. bdd : to capture the structure of configurations, programs and FBs ibd: to capture the interconnections among the constituent parts of constructs, such as configurations, programs and FBs SysML can be used to provide a completely graphical environment for modeling control applications in a higher and also more expressive layer than the one already supported by IEC market tools. K.Thramboulidis ETFA

8 The proposed development process act Development Process P&IDs m2m transformer Semi automated early design process Elaborate the design spec PCE req. (in SysML) PCE final req. (in SysML) Early design specs (in SysML) detailed design specs (in SysML) Add extra req. elaborate req. m2m transformer Detailed design spec (in PLCopen XML) K.Thramboulidis ETFA The PCE requirements profile K.Thramboulidis ETFA

9 Towards a SysML profile for IEC61131 K.Thramboulidis ETFA Concluding Remarks IEC has already introduced basic concepts of the OO and MDD. However, it fails to support a high level of abstraction specification of the system, and has a great semantic gap from PCE requirements IEC61499, UML, SysML were examined to address the increasing size and complexity of industrial applications SysML supports higher layers of abstraction in system specification, Provides effective handling of requirements and traceability to the design time modeling artifacts, and supports both the procedural and the OO programming paradigms. K.Thramboulidis ETFA