An architecture to integrate IEC 61131-3 systems in an IEC 61499 distributed solution

The IEC 61499 standard has been developed to allow the modeling and design of distributed control systems, providing advanced concepts of software engineering (such as abstraction and encapsulation) to the world of control engineering. The introduction of this standard in already existing control environments poses challenges, since programs written using the widespread IEC 61131-3 programming standard cannot be directly executed in a fully IEC 61499 environment without reengineering effort. In order to solve this problem, this paper presents an architecture to integrate modules of the two standards, allowing the exploitation of the benefits of both. The proposed architecture is based on the coexistence of control software of the two standards. Modules written in one standard interact with some particular interfaces that encapsulate functionalities and information to be exchanged with the other standard. In particular, the architecture permits to utilize available run-times without modification, it allows the reuse of software modules, and it utilizes existing features of the standards. A methodology to integrate IEC 61131-3 modules in an IEC 61499 distributed solution based on such architecture is also developed, and it is described via a case study to prove feasibility and benefits. Experimental results demonstrate that the proposed solution does not add substantial load or delays to the system when compared to an IEC 61131-3 based solution. By acting on task period, it can achieve performances similar to an IEC 61499 solution

Obfuscation of function block diagrams

Obfuscation is a process of transforming a program into an equivalent version which is harder to understand and reverse-engineer. Little attention has been paid to obfuscation techniques for programs written for programmable logic controllers (PLC). However, there is no reason to assume that an attacker would not be interested in hiding malicious payload into a PLC program before it is compiled to machine code.In this paper, I present five techniques for obfuscating IEC 61131-3 Function Block Diagram (FBD) programs. Four of the techniques are specific to the graphical representation of FBD. I then evaluate the applicability of each technique by experimenting with different PLC programming tools. I prove that at least four of the techniques are practically applicable, and demonstrate features that some tools successfully use to prevent abuse. Stricter rules, if implemented in IEC 61131-3, would prevent some of the techniques listed

Obfuscation of function block diagrams

Obfuscation is a process of transforming a program into an equivalent version which is harder to understand and reverse-engineer. Little attention has been paid to obfuscation techniques for programs written for programmable logic controllers (PLC). However, there is no reason to assume that an attacker would not be interested in hiding malicious payload into a PLC program before it is compiled to machine code.In this paper, I present five techniques for obfuscating IEC 61131-3 Function Block Diagram (FBD) programs. Four of the techniques are specific to the graphical representation of FBD. I then evaluate the applicability of each technique by experimenting with different PLC programming tools. I prove that at least four of the techniques are practically applicable, and demonstrate features that some tools successfully use to prevent abuse. Stricter rules, if implemented in IEC 61131-3, would prevent some of the techniques listed

Automatic translation from FBD-PLC-programs to NuSMV for model checking safety-critical control systems

Programmable logic controllers (PLCs) are digital control systems, commonly used in industrial automation and safety-critical applications. Control systems used in safety-critical areas must undergo an extensive and thorough certification and verification process. In safety-critical applications, the PLC programming standard IEC 61131-3 is widely accepted in industry. PLC programmers who develop control systems for safety-critical systems are often required to verify the logic of PLCs by using formal methods such as model checking. Translating manually from a PLC program to the input language of a model checker takes times and is often error-prone. We develop a compiler to automatically translate PLC programs in the function block diagram (FBD) language, one of five industry standard PLC programming notations, to the input language of the model checker NuSMV. We have evaluated correctness, robustness, and performance of the PLC-NuSMV compiler using a case study. Evaluation results show that the compiler can translate the PLC programs correctly. The compiler can also identify several input errors and can scale to relative large PLC programs

Evaluating XMPP Communication in IEC 61499-based Distributed Energy Applications

The IEC 61499 reference model provides an international standard developed specifically for supporting the creation of distributed event-based automation systems. Functionality is abstracted into function blocks which can be coded graphically as well as via a text-based method. As one of the design goals was the ability to support distributed control applications, communication plays a central role in the IEC 61499 specification. In order to enable the deployment of functionality to distributed platforms, these platforms need to exchange data in a variety of protocols. IEC 61499 realizes the support of these protocols via "Service Interface Function Blocks" (SIFBs). In the context of smart grids and energy applications, IEC 61499 could play an important role, as these applications require coordinating several distributed control logics. Yet, the support of grid-related protocols is a pre-condition for a wide-spread utilization of IEC 61499. The eXtensible Messaging and Presence Protocol (XMPP) on the other hand is a well-established protocol for messaging, which has recently been adopted for smart grid communication. Thus, SIFBs for XMPP facilitate distributed control applications, which use XMPP for exchanging all control relevant data, being realized with the help of IEC 61499. This paper introduces the idea of integrating XMPP into SIFBs, demonstrates the prototypical implementation in an open source IEC 61499 platform and provides an evaluation of the feasibility of the result.Comment: 2016 IEEE 21st International Conference on Emerging Technologies and Factory Automation (ETFA

Automated system for studying feedback regulators

Bundled software intended for realization of different control algorithms constructed on the basis of functional units on medium-priced industrial controllers have been considered. The example of programming in a language of functional block diagrams of algorithm of real processing automation is give