Formalization and Modeling of IEC 61499 Function Block Systems

IEEE International Conference on Systems, Man and Cybernetics, 2002

After having sketched the different techniques enabling to check properties of Discrete Event Systems control software, we present in this article a formal method for IEC 61499 function blocks diagrams verification. This method is based on a formal representation of the behaviour of function blocks diagrams and takes benefit of verification tools developed from the SIGNAL synchronous language.

IEEE Transactions on Industrial Informatics, 2000

The international standard IEC 61499 for the design of distributed industrial control systems defines an abstract model of function blocks (FB) which allows many different semantic interpretations. As a consequence, in addition, so-called execution models were proposed to specify the execution order of FBs. The variety of models leads to the incompatibility of tools and hinders the portability of automation software. To achieve a degree of execution model independence, in this paper, design patterns are suggested that make FB systems-robust to changes of execution semantics. A semantic-robust pattern is defined for a particular source execution model. The patterns themselves are implemented by means of the FB apparatus and therefore are fairly universal. The patterns can be defined and implemented using the FB transformations expressed in terms of Attributed Graph Grammars.

Proceedings of the 18th IFAC World Congress, 2011

The paper deal with a deep analysis and application of object-oriented methodologies for the design process of industrial machine controllers. The process pass thought the phases of (1) conceptual model development of the software artifacts, and (2) model code deployment for the automation system target, which is in general a Programmable Logic Controller (PLC) compliant with the international standard IEC 61131-3 for programming languages. The paper describes a design pattern for the software conceptual model deployment, with a particular emphasis on practical requirements enforced by PLC of different brands. In fact, IEC 61131-3 compliance provides a common "look-and-feel" for programming languages, but does not guarantee straightforward code portability between different PLC vendors. The paper has a great focus on applications and provides an example, based on a generic flow-pack machine, to better explain the proposed methodology.

2010 8th IEEE International Conference on Industrial Informatics, 2010

In order for industrial automation manufacturers to remain competitive, they must utilise modern design approaches. Existing approaches using IEC 61131 langauges are not object oriented and are difficult to reconfigure for other applications. IEC 61499 is an open standard aimed at replacing IEC 61131, adding modern design features and hardware abstraction. Therefore there is a need to migrate existing code bases using IEC 61131 technologies into the newer IEC 61499 language for future development.

2009 IEEE Conference on Emerging Technologies & Factory Automation, 2009

This paper provides a possibility for a semantic correct transformation of existing IEC 61131-3 projects into the newer IEC 61499 standard. Based on a model driven development approach as well as proper concepts and rules this paper describes a suitable way to overcome some semantical problems which occurred during the transformation process. Those semantical problems regard some differences between the libraries of IEC 61131-3 and IEC 61499 as well as the extraction of the actual execution sequence of IEC 61131-3 programs. Both issues are supposed to be solved by auxiliary transformations. One static transformation which converts IEC 61131-3 Function Blocks into Simple Function Blocks. And one project dependent transformation which extracts the execution order of IEC 61131-3 Function Block networks. myListOfEntity.sortBy(entity | entity. name)

WSEAS Transactions on Computers, 2009

The Function Block (FB) model was first standardized by the 1131 standard of the International Electrotechnical Commission (IEC) for programmable controllers. This standard was successfully adopted by the industry but it seems to have several constraints for the development of today's complex embedded control and automation systems. These constraints are mainly imposed by the procedural programming paradigm and the device centric approach that are adopted by the standard. The IEC to address these constraints proposed the 61499 standard that is an attempt to exploit object-orientation and the application-centric paradigm in the control and automation domain. In this paper, the FB models of 1131 and 61499 are briefly described and several unclear issues related to the programming paradigms adopted, interoperability, composability and execution semantics of these FB models are clarified. The paper focuses on the execution semantics of the 61499 standard since this is one of the most important reasons that the industry has not yet accepted this standard.

IEEE Transactions on Computers, 2000

IEC 61499 has been endorsed as the standard for modelling and implementing distributed industrial-process measurement and control systems. The standard prescribes the use of function blocks for designing systems in a componentoriented approach. The execution model of a basic function block and the manner for event/data connections between blocks are described therein. Unfortunately, the standard does not provide exhaustive specifications for function block execution. Consequently, multiple standard-compliant implementations exhibiting different behaviours are possible. This not only defeats the purpose of having a standard, but makes verification of function block systems difficult. To overcome this, we propose synchronous semantics for function blocks, and show its feasibility by translating function blocks into a subset of Esterel, a wellknown synchronous language. The proposed semantics avoids causal cycles common in Esterel, and is proven to be reactive and deterministic under any composition. Moreover, verification techniques developed for synchronous systems can now be applied to function blocks.

IEEE Industrial Electronics Magazine, 2000

IEC 61499 Function Block Model: Facts and Fallacies by Kleanthis Thramboulidis C ontrol and automation systems in factory automation are developed using the procedural and device-centric paradigms. The always-increasing complexity of systems in this domain, as well as the need for agility, flexible plugand-play, extensibility, and evolution, imposes the need for new paradigms to effectively address today's requirements. The function block (FB) model, introduced by the IEC 61499 standard [1], is an attempt to open the industrial systems market and exploit current software engineering practices and the application-centric paradigm in this domain. The IEC 61499 standard is also an attempt to address requirements such as interoperability, portability, distribution, agility, run-time reconfigurability, higher availability, and reliability. It is supposed to 1) facilitate the exchange of design information between designers and fabrication houses and 2) allow the designers to integrate competing vendors' tools and reduce the risk of relying on proprietary languages and data formats. However, even though the standard has been officially accepted by 2005, it is not yet adopted by the industry [2]-[4], and its status in the academic research community is questionable. In this article, the current status of the standard is described, and its drafting process as well as its validation prior to implementation is commented. Facts and fallacies are presented and properly discussed to

IEEE Access, 2022

This paper presents the core concepts for the poST language-a process-oriented extension of the IEC 61131-3 Structured Text (ST) language which intends to provide a conceptual consistency of the PLC source code with technological description of the plant operating procedure. The poST can be seamlessly used as a textual programming language for complex PLC software in the context of IEC 61131-3 (3 rd Edition). The language combines the advantages of FSM-based programming with the conventional syntax of the ST language which would facilitate its adoption. The poST language assumes that a poST-program is a set of weakly connected concurrent processes, structurally and functionally corresponding to the technological description of the plant. Each process is specified by a sequential set of states. The states are specified by a set of the ST constructs, extended by TIMEOUT operation, SET STATE operation, and START / STOP / check state operations to communicate with other processes. The paper describes the basic syntax of the poST language, demonstrates the usage of the poST language by developing control software for an elevator, and compares the development in poST with pure Structured Text. INDEX TERMS Computer languages, IEC 61131-3 standard, PLC software development, process-oriented programming.

Science of Computer Programming, 2015

Many industrial control systems use programmable logic controllers (PLCs) since they provide a highly reliable, off-the-shelf hardware platform. On the programming side, function blocks (FBs) are reusable components provided by the PLC supplier that can be combined to implement the required system behaviour. A higher quality system may be realized if the FBs are pre-certified to be compliant with an international standard such as IEC 61131-3. We present an approach: 1) to create complete and unambiguous FB requirements using tabular expressions; and 2) to verify the consistency and correctness of FB implementations in the PVS proof environment. We apply our approach to the examples in the informative Appendix F of the IEC 61131-3 standard. We examined the entire library of FBs and their supplied implementations described in structured text (ST) and function block diagrams (FBDs). Our approach identified issues in the informative examples, including: a) ambiguous behavioural descriptions; b) missing assumptions; and c) inconsistent implementations. We also proposed solutions to these issues.

2006 IEEE Conference on Emerging Technologies and Factory Automation, 2006

This paper presents a new approach to modelling and verification of function block applications of the IEC 61499 standard. The approach uses the language of logic programming Prolog to represent a model of function block network and to verify its properties. The class of properties that can be checked is extended to more substantial queries providing in return not only "yes" or "no", but also the parameters explaining the reasons. The models essentially use the topological properties of the function block network and allow data of arbitrary types (not only Boolean) be used in the queries.

2015 IEEE Trustcom/BigDataSE/ISPA, 2015

The IEC 61499 standard proposes an event driven execution model for distributed control applications for which an informal execution semantics is provided. Consequently, run-time implementations are not rigorously described and therefore their behavior relies on the interpretation made by the tool provider. In this paper, as a step towards a formal semantics, we focus on the Execution Control Chart semantics, which is fundamental to the dynamic behavior of Basic Function Block elements. In particular we develop a well-formedness criterion that ensures a finite number of Execution Control Chart transitions for each triggering event. We also describe the first step towards the mechanization of the well-formedness checking algorithm in the Coq proof-assistant so that, ultimately, we are able to show, once and for all, that this algorithm is effectively correct with respect to our proposed execution semantics. The algorithm is extractable from the mechanization in a correct-by-construction way, and can be directly incorporated in certified toolchain for analysis, compilation and execution of IEC 61499 models. As a proof of concept a prototype tool RTFM-4FUN has been developed. It performs well-formedness checks on Basic Function Blocks using the extracted algorithm's code.

Industrial Informatics, 2008. …, 2008

The Function Block (FB) is proposed by IEC 61499 as the basic construct for the development of reusable, interoperable, distributed control applications. The FB designlevel construct is clearly described by the standard so various prototype development environments have been developed during last years. However, implementation model issues are not explicitly addressed and this is one of the main reasons for the fact that the FB model has not been yet adopted by industry. In this paper, we describe implementation model alternatives with main focus on the mapping of the FB network constructs to the target execution environment RTOS tasks. Schedulability analysis techniques are also considered to provide a framework for the automatic synthesis of the implementation model. The objective is to guarantee the same standard set of execution semantics independent of the execution environment.

… and Factory Automation, 2006. ETFA'06. …, 2006

The International Electro-technical Commission through the 61499 standard establishes the basic infrastructure towards an open market in the control and automation domain.