Utjecaj komunikacijskih prekida na zadovoljenje funkcionalnih zahtjeva IEC 61131-3 distribuiranih sustava upravljanja

The control software is frequently used in various systems that perform important and responsible tasks in industry. During its development, it is crucial to ensure that the solution is created in a way consistent with assumptions and meets all functional requirements. One of important steps consists of testing particular software units, separated from the rest of system, using the off-line simulator. However, test results can be different in case of a fully-connected system when external factors, such as communication issues, should be also taken into account. In this paper, the authors present a concept of specification and execution of system tests, using the dedicated test definition language, named CPTest+. It has been extended by the additional ASSERT_COM instruction, which performs an assertion that is able to detect problems related to external factors, including communication. To enable automatic and systematic testing, the dedicated metric has been proposed. It takes into account the current link status and archived results to calculate the probability that the test case has failed due to communication problems.Upravljački software je često korišten u sustavima koji obavljaju kritične zadatke u industriji. Tijekom njegovog razvoja, važno je osigurati zadovoljenje svih bitnih pretpostavki i funkcionalnih zahtjeva. Jedan od važnih koraka u razvoju navedenog softwarea je testiranje njegovih pojedinih cjelina korištenjem offline simulatora, neovisno o ostatku sustava. Međutim, rezultati testiranja mogu se bitnije razlikovati u slučaju potpuno povezanog sustava sa svim pripadajućim eksternim faktorima, kao što su komunikacijski problemi, koje je također potrebno uzeti u obzir. U ovom radu autori predstavljaju koncept definiranja i izvršenja testova sustava korištenjem jezika za namjensko definiranje testova, nazvanog CPTest+. On je proširen dodatnom ASSERT_COM naredbom koja obavlja provjeru s mogućnošću detekcije problema uzrokovanih vanjskim faktorima, npr. komunikacijom. Kako bi se omogućilo automatsko i sistematično testiranje predložen je namjenski mjerni sustav. On uzima u obzir trenutni status veze kao i arhivirane rezultate kako bi se odredila vjerojatnost neizvršenja testnog slučaja uslijed komunikacijskih problema

Measuring the Overall Complexity of Graphical and Textual IEC 61131-3 Control Software

Software implements a significant proportion of functionality in factory automation. Thus, efficient development and the reuse of software parts, so-called units, enhance competitiveness. Thereby, complex control software units are more difficult to understand, leading to increased development, testing and maintenance costs. However, measuring complexity is challenging due to many different, subjective views on the topic. This paper compares different complexity definitions from literature and considers with a qualitative questionnaire study the complexity perception of domain experts, who confirm the importance of objective measures to compare complexity. The paper proposes a set of metrics that measure various classes of software complexity to identify the most complex software units as a prerequisite for refactoring. The metrics include complexity caused by size, data structure, control flow, information flow and lexical structure. Unlike most literature approaches, the metrics are compliant with graphical and textual languages from the IEC 61131-3 standard. Further, a concept for interpreting the metric results is presented. A comprehensive evaluation with industrial software from two German plant manufacturers validates the metrics' suitability to measure complexity.Comment: 8 pages, https://ieeexplore.ieee.org/abstract/document/9444196

Concept and Implementation of a Factory Simulation

Current technological trends, such as cyber-physical systems and the industrial internet of things (IIoT), blur boundaries between software and hardware development. Industrial software systems control whole production factories by using advanced information technology approaches. Hence, the development of such systems requires a tight integration of data and processes between the different software systems, e.g., programmable logic controllers, production planning systems, or enterprise resource planning software. This thesis provides the concept and implementation of a factory simulation including the development of a programmable logic controller (PLC) application based on PLC programming languages. The PLC application controls the execution of customizable production processes and generates process data, e.g., sensor data, production logs, or alarm events, which can be further analyzed, for example, in condition monitoring applications

Study on influence of the new CoDeSys V3.0 on the existing CoDeSys discipline of the Mind8 Engineering Center

CoDeSys "Controller Development Systems" is a development environment for programming in the area of automation controllers. It is an open source solution completely in line with the international industrial standard IEC 61131-3. All five programming languages for application programming as defined in IEC 61131-3 are available in the development environment. These features give professionals greater flexibility with regard to programming and allow control engineers have the ability to program for many different applications in the languages in which they feel most comfortable. Over 200 manufacturers of devices from different industrial sectors offer intelligent automation devices with a CoDeSys programming interface. In 2006, version 3 was released with new updates and tools. One of the great innovations of the new version of CoDeSys is object oriented programming. Object oriented programming (OOP) offers great advantages to the user for example when wanting to reuse existing parts of the application or when working on one application with several developers. For this reuse can be prepared a source code with several well known parts and this is automatically generated where necessary in a project, users can improve then the time/cost/quality management. Until now in version 2 it was necessary to have hardware interface called “Eni-Server” to have access to the generated XML code. Another of the novelties of the new version is a tool called Export PLCopenXML. This tool makes it possible to export the open XML code without the need of specific hardware. This type of code has own requisites to be able to comply with the standard described above. With XML code and with the knowledge how it works it is possible to do component-oriented development of machines with modular programming in an easy way. Eplan Engineering Center (EEC) is a software tool developed by Mind8 GmbH & Co. KG that allows configuring and generating automation projects. Therefore it uses modules of PLC code. The EEC already has a library to generate code for CoDeSys version 2. For version 3 and the constant innovation of drivers by manufacturers, it is necessary to implement a new library in this software. Therefore it is important to study the XML export to be then able to design any type of machine. The purpose of this master thesis is to study the new version of the CoDeSys XML taking into account all aspects and impact on the existing CoDeSys V2 models and libraries in the company Harro Höfliger Verpackungsmaschinen GmbH. For achieve this goal a small sample named “Traffic light” in CoDeSys version 2 will be done and then, using the tools of the new version it there will be a project with version 3 and also the EEC implementation for the automatically generated code

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

Compiler Front-end for the IEC 61131-3 v3 Languages

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Hardware Simulation for Testing IEC 61131-3

Testing of control code written in IEC 61131-3 has long been a strenuous manual process. The focus in this master's thesis is on building a simulator of an Alfa Laval separator to enable testing of control code. In this particular case, the control code being tested is written and executed in a soft PLC called TwinCAT. The simulator for testing code is written in C#. When testing code, automated tests are preferred because it enables easy regression testing. For this purpose a testing tool using a customized script language has been developed. Testing with a simulator is also beneficial because errors can be found early in the development process, thus reducing the number of errors left to be found when testing on hardware. Comparison tests show that the simulator performs sufficiently well for testing of control code

Increasing System Test Coverage in Production Automation Systems

An approach is introduced, which supports a testing technician in the identification of possibly untested behavior of control software of fully integrated automated production systems (aPS). Based on an approach for guided semi-automatic system testing, execution traces are recorded during testing, allowing a subsequent coverage assessment. As the behavior of an aPS is highly dependent on the software, omitted system behavior can be identified and assessed for criticality. Through close cooperation with industry, this approach represents the first coverage assessment approach for system testing in production automation to be applied on real industrial objects and evaluated by industrial experts