On Structuring Events for IOPT Net Models

Part 9: Embedded Systems and Petri NetsInternational audienceThis paper presents a proposal for structuring events for system models expressed using IOPT nets (Input-Output Place-Transition Petri nets). Currently, a non-autonomous event within an IOPT model is defined based on change of input signals with respect to a specific threshold, when two consecutive execution steps are considered. New types of events are proposed allowing the definition of an event activated not only by crossing a fixed threshold, but also considering a change in associated signal value on a specific amount (belonging to an interval of values). The concept is further extended allowing the definition of an event based on signal values presented on previous execution steps. The proposal results on a classification of several types of events, namely threshold events, momentum events, impetus events, as well as delayed events and logical events. Usage of these types of events allows improvements in terms of expressiveness and compactness of the resulted model

Asynchronous interfaces for IOPT-Flow to support GALS systems

45th Annual Conference of the IEEE Industrial Electronics Society: Lisbon, Portugal: oct. 14-17, 2019Throughout the course of time, distributing a global clock signal over a synchronous circuit has become a demanding task as a result of the broadening size and complexity of modern circuits. Globally Asynchronous Locally Synchronous (GALS) systems emerge as a solution to the laborious task of distributing a global clock over a large circuit, through the partitioning of said circuit into smaller, and therefore, more manageable blocks. The DS-Pnet (Dataflow, Signals and Petri nets) modelling language and its associated framework IOPT-Flow focus on supporting the development of cyber-physical systems, however, they may be a strong push to the development of GALS systems, through their multiple available tools that comprise a graphical editor, a simulator and automatic code generation tools, namely a VHDL (VHSIC Hardware Description Language) code generator. In order to facilitate the implementation of said GALS system in the IOPT-Flow framework, some components were created, these work together to form asynchronous interfaces that are a crucial element to any GALS system, thus providing options to designers that intent to develop a GALS system utilizing the IOPT-Flow framework

Geração automática de código ANSI C a partir de Redes de Petri IOPT - PNML2C -

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Engenharia Electrotécnica e de ComputadoresNesta dissertação apresenta-se a elaboração de regras de tradução e o desenvolvimento de uma ferramenta de geração de código na Linguagem ANSI C a partir de Redes de Petri IOPT especificadas em PNML. As redes de Petri IOPT resultam da extensão das redes de Petri Lugar-Transição com algumas características não autónomas,como sinais e eventos de entrada e saída. Para cada característica dos modelos expressos em Redes de Petri IOPT são definidas as estruturas necessárias em ANSI C para a sua execução, de forma a garantir a semântica pretendida. A ferramenta desenvolvida recebe o modelo do controlador expresso através de um modelo IOPT através de um ficheiro no formato PNML, ao qual foram adicionadas as representações dos elementos específicos das redes IOPT. O modelo é analisado e é criado um conjunto de cinco ficheiros preparados para, apenas com a definição do interface com a plataforma de implementação, executar a rede de acordo com a semântica definida. Foram criados dois interfaces para a ferramenta, um gráfico para ser usado por humanos e outro por comandos para facilitar a integração com outras ferramentas. Criou-se ainda uma nova ferramenta com o mesmo objectivo mas utilizando um novo meta-modelo das Redes de Petri IOPT de forma a tratar as alterações introduzidas por este meta-modelo. As ferramentas desenvolvidas foram validadas através de exemplos de sistemas de automação

IOPT Petri Net State Space Generation Algorithm with Maximal-Step Execution Semantics

This paper presents an algorithm to efficiently generate the state-space of systems specified using the IOPT Petri-net modeling formalism. IOPT nets are a non-autonomous Petri-net class, based on Place-Transition nets with an extended set of features designed to allow the rapid prototyping and synthesis of system controllers through an existing hardware-software co-design framework. To obtain coherent and deterministic operation, IOPT nets use a maximal-step execution semantics where, in a single execution step, all enabled transitions will fire simultaneously. This fact increases the resulting state-space complexity and can cause an arc "explosion" effect. Real-world applications, with several million states, will reach a higher order of magnitude number of arcs, leading to the need for high performance state-space generator algorithms. The proposed algorithm applies a compilation approach to read a PNML file containing one IOPT model and automatically generate an optimized C program to calculate the corresponding state-space

Modelização de Eventos: aplicação a modelos de interação do sistema com o ambiente

Neste trabalho propõe-se um conjunto de técnicas de modelização de eventos potencialmente utilizáveis em complemento a formalismos de modela-ção (Diagramas de Estado e redes de Petri, entre outros) de sistemas a eventos discretos. São definidos eventos de entrada e eventos de saída do sistema. Os eventos de entrada são originados pela análise da evolução de sinais e (outros) eventos de entrada e permitem representar comportamentos complexos das en-tradas do sistema, enquanto os eventos de saída permitem gerar sinais e (ou-tros) eventos de saída. São propostos eventos e condições elementares que detetam comporta-mentos elementares dos sinais e também composições de eventos e condições, incluindo relações de ordem temporal, de forma a obter caracterizações mais abstratas e melhorias na legibilidade e compactação do modelo. Para representar as técnicas de modelização propostas são definidas duas sintaxes diferentes (gráfica ou textual). A definição destes dois tipos de sintaxe permite a sua integração em diferentes ambientes de desenvolvimento de sis-temas. Desta forma, a principal contribuição deste trabalho foca-se na modeliza-ção da interação do sistema com o ambiente, partindo da decomposição do mo-delo do sistema em partes de interface e de execução (que comunicam através de eventos), e da adição de uma caracterização separada das dependências e dos comportamentos dos sinais de entrada e de saída com o ambiente resultan-do numa modelação estruturada do sistema, dando, assim, origem a modelos mais compactos e mais simples de interpretar e implementar

Towards remote monitoring and reconfiguration of FPGA-based controllers using IOPT-Tools

This work was partially financed by Portuguese Agency ”Fundac¸ao para a Ci ˜ encia e a Tecnologia” (FCT), in the ˆ framework of project UID/EEA/00066/2019.IOPT-Tools is a tool chain framework that supports controllers’ specification through Petri net models, models’ validation, and automatic generation of C and VHDL (VHSIC Hardware Description Language) code. Additionally, this framework supports the remote control and monitoring of embedded controllers that were implemented using the automatically generated C code. This paper presents an ongoing work where IOPT-Tools will be extended to support the remote control and monitoring of FPGA (Field Programmable Gate Array) based controllers. Additionally, the IOPT-Tools will be also extended to support the remote reconfiguration of FPGA-based controllers, enabling their adaptation to new application requirements.publishersversionpublishe

Annotation rules for XML schemas with grouped semantic annotations

45th Annual Conference of the IEEE Industrial Electronics Society: Lisbon, Portugal: oct. 14-17, 2019To enable the Industrial Internet of Things (IIoT), it is required to ensure Machine-to-Machine communications. Systems/devices often use different communication protocols, standards, and data representation languages, which create interoperability challenges. This paper proposes a set of annotation rules for systems meta-data, to support the translation of data exchanged between heterogeneous systems. These rules must be followed to ensure the validity of systems meta-data (XML Schemas annotated with semantic annotations and group identifiers). The meta-data can then be used as input in tools to analyze data and semantic compatibility and generate translators

JSON Schemas with Semantic Annotations Supporting Data Translation

Funding Information: Funding: This research was partially funded by EU ECSEL Joint Undertaking (JU) under grant agreement n° 826452 (project Arrowhead Tools).As service-oriented architectures are a solution for large distributed systems, interoperabil-ity between these systems, which are often heterogeneous, can be a challenge due to the different syntax and semantics of the exchanged messages or even different data interchange formats. This paper addresses the data interchange format and data interoperability issues between XML-based and JSON-based systems. It proposes novel annotation mechanisms to add semantic annotations and complement date values to JSON Schemas, enabling an interoperability approach for JSON-based systems that, until now, was only possible for XML-based systems. A set of algorithms supporting the translation from JSON Schema to XML Schema, JSON to XML, and XML to JSON is also pro-posed. These algorithms were implemented in an existing prototype tool, which now supports these systems’ interoperability through semantic compatibility verification and the automatic generation of translators.publishersversionpublishe

Finding Learning Paths Using Petri Nets Modeling Applicable to E-Learning Platforms

Part 6: Petri NetsInternational audienceThis work proposes an approach for course modeling using Petri nets. The proposed modeling method can be applied to support development of e-learning platforms (namely learning management systems - LMS) allowing student guidance when considering reaching a specific goal. This goal could be as simple as getting a set of sequential courses (or a degree), or as complex as combining different modules from different courses having different types of dependencies in order to obtain a qualification. Each course is characterized by a set of modules and their relations. Each module is represented by a Petri net model and the module structure representing the course’s dependency relations is translated into another Petri net model. Additional courses or modules can be included into the offer as their associated Petri net models can be easily composed using net addition operation. The contribution of this paper foresees the usage of common Petri nets analysis techniques (such as state space analysis, invariants, trace finding) to constraint student’s options in order to optimize his/her path to reach a degree or a qualification. A simple example considering a scenario with a few courses and modules is used to illustrate the approach

Analysis and Generation of Logical Signals for Discrete Events Behavioral Modeling

Part 6: Embedded SystemsInternational audienceThis paper presents a proposal for structuring logical signals for discrete events behavioral modeling. Graphical formalisms will be used to illustrate applicability of the proposed techniques. Input logical signals are generated based on the analysis of physical signals coming from the environment and other input logical signals. Their analysis is introduced in the flow of the input signal analysis, defined as pre-processing when using a modeling formalism. Their analysis is done in the first step of pre-processing, allowing to put these signals at the same level of the physical ones, enabling its use in the rest of the signals’ analysis, and also allowing the generation of events and conditions associated with these signals. Likewise, logical signals are also defined in the flow of post-processing, allowing the definition of output logical signals through analysis and composition of the output signals generated by the model execution. The output logical signals are analyzed in the last step of post-processing in order to allow the use of the signals affected by the events in its analysis. The usage of these signals allows improvements in terms of expressiveness and compactness of the resulted models, both directly due to its use as well as by the increase of the possibilities of analysis provided to the following parts of the development flow