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  • 1.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Eriksson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pereira, David J.
    ISEP, Instituto Superior de Engenharia do Porto.
    Pinho, Luis Miguel
    ISEP, Instituto Superior de Engenharia do Porto.
    Response Time for IEC 61499 over Ethernet2015In: IEEE International Conference on Industrial Informatics: INDIN 2015, Cambridge, UK, July 22-24, 2015. Proceedings, Piscataway, NJ: IEEE Communications Society, 2015, p. 1206-1212, article id 7281907Conference paper (Refereed)
    Abstract [en]

    The IEC 61499 standard provides means to specify distributed control systems in terms of function blocks. For the deployment, each device may hold one or many logical resources, each consisting of a function block network with service interface blocks at the edges. The execution model is event driven (asynchronous), where triggering events may be associated with data (and seen as a message). In this paper we propose a low complexity implementation technique allowing to asses end-to-end response time of event chains spanning a networked devices. Based on a translation of IEC 61499 to RTFM-tasks and resources, the response time for each task in the system can be derived using established scheduling techniques. In this paper we develop a method to provide safe end-to-end response time taking both intra- and inter-device delivery delays into account. As a use case we study the implementation onto (single-core) ARMcortex based devices communicating over a switched Ethernet network. For the analysis we define a generic switch model, and an experimental setup allowing us to study the impact of network topology as well as 802.1Q quality of service in a mixed critical setting. Our results indicate that safe sub milli-second end-to-end response times can be obtained using the proposed approach.

  • 2.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Eriksson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pereira, David
    ISEP, Instituto Superior de Engenharia do Porto.
    Pinho, Luis Miguel
    ISEP, Instituto Superior de Engenharia do Porto.
    End-to-End Response Time of 61499 Distributed Applications over Switched Ethernet2017In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, no 1, p. 287-297Article in journal (Refereed)
    Abstract [en]

    The IEC 61499 standard provides means to specify distributed control systems in terms of function blocks. For the deployment, each device may hold one or many logical resources, each consisting of a function block network with service interface blocks at the edges. The execution model is event driven (asynchronous), where triggering events may be associated with data (and seen as messages). In this paper, we propose a low complexity implementation technique allowing to assess end-to-end response times of event chains spanning over a set of networked devices. Based on a translation of IEC 61499 to RTFM1-tasks and resources, the response time for each task in the system at device-level can be derived using established scheduling techniques. In this paper, we develop a holistic method to provide safe end-to-end response times taking both intra- and inter-device delivery delays into account. The novelty of our approach is the accuracy of the system scheduling overhead characterization. While the device-level (RTFM) scheduling overhead was discussed in previous works, the network-level scheduling overhead for switched Ethernets is discussed in this paper. The approach is generally applicable to a wide range of COTS Ethernet switches without a need for expensive custom solutions to provide hard real-time performance. A behavior characterization of the utilized switch determines the guaranteed response times. As a use case, we study the implementation onto (single-core) ARMcortex based devices communicating over a switched Ethernet network. For the analysis, we define a generic switch model and an experimental setup allowing us to study the impact of network topology as well as 802.1Q quality of service in a mixed critical setting. Our results indicate that safe sub millisecond end-to-end response times can be obtained using the proposed approach.

  • 3.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Fresk, Emil
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pereira, David J.
    ISEP, Instituto Superior de Engenharia do Porto.
    Pinho, Luis Miguel
    ISEP, Instituto Superior de Engenharia do Porto.
    Abstract Timers and their Implementation onto the ARM Cortex-M family of MCUs2016In: SIGBED Review, E-ISSN 1551-3688, Vol. 13, no 1Article in journal (Refereed)
    Abstract [en]

    Real-Time For the Masses (RTFM) is a set of languages andtools being developed to facilitate embedded software developmentand provide highly ecient implementations gearedto static verication. The RTFM-kernel is an architecturedesigned to provide highly ecient and predicable Stack ResourcePolicy based scheduling, targeting bare metal (singlecore)platforms.We contribute by introducing a platform independent timerabstraction that relies on existing RTFM-kernel primitives.We develop two alternative implementations for the ARMCortex-M family of MCUs: a generic implementation, usingthe ARM dened SysTick/DWT hardware; and a targetspecic implementation, using the match compare/free runningtimers. While sacricing generality, the latter is moreexible and may reduce overall overhead. Invariants for correctnessare presented, and methods to static and run-timeverication are discussed. Overhead is bound and characterized.In both cases the critical section from release timeto dispatch is less than 2us on a 100MHz MCU. Queue andtimer mechanisms are directly implemented in the RTFMcorelanguage (-core in the following) and can be includedin system-wide scheduling analysis.

  • 4.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Eriksson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Real-Time Execution of Function Blocks for Internet of Things using the RTFM-kernel2014In: Proceedings of 2014 IEEE 19th International Conference on Emerging Technologies & Factory Automation (ETFA 2014): Barcelona, Spain, 16-19 Sept. 2014, Piscataway, NJ: IEEE Communications Society, 2014, p. 1-6, article id 7005232Conference paper (Refereed)
    Abstract [en]

    Function Blocks provides a means to model andprogram industrial control systems. The recently acclaimed IEC61499 standard allows such system models to be partitioned andexecuted in a distributed fashion. At device level, such models aretraditionally implemented onto programmable logic controllersthat underneath have an operating system and a softwarerun-time environment which implies high resource demands.However, there is a current trend to involve small embeddedsystems (so called Internet of Things devices) integrated into suchdistributed control systems. To this end, we seek to address theoutsets for real-time execution of Function Block based designsonto light-weight controllers (MCUs) with limited resources(memory and CPU). Furthermore, we propose a mapping ofthe Function Block execution semantics onto the RTFM-kernel,and discuss opportunities for off-line (design time) analysis withrespect to response time, overall schedulability and memoryrequirements.

  • 5.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Eriksson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    RTFM-4-FUN2014In: 2014 9th IEEE International Symposium on Industrial Embedded Systems (SIES 2014): Pisa, 18-20 June 2014, Piscataway, NJ: IEEE Communications Society, 2014Conference paper (Refereed)
    Abstract [en]

    Function Blocks provides a means to model andprogram industrial control systems. The recently acclaimed IEC61499 standard allows such system models to be partitioned andexecuted in a distributed fashion. At device level, such models aretraditionally implemented onto programmable logic controllersand industrial PCs. In this paper, we discuss work in progresson developing a mapping allowing to implement a subset of IEC61499 models onto light-weight embedded devices (MCUs). Wepropose and detail an event semantics, and its mapping to thenotions of tasks and resources for Stack Resource Policy basedanalysis and scheduling. Moreover, we show how the proposedmapping can be efficiently implemented under the RTFM-kernel.Finally we outline a prototype tool-chain and discuss related,ongoing and future work.

  • 6.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pereira, David J.
    ISEP, Instituto Superior de Engenharia do Porto.
    Pinho, Luis Miguel
    ISEP, Instituto Superior de Engenharia do Porto.
    RTFM-core: Language and Implementation2015In: 2015 IEEE 10th Conference on Industrial Electronics and Applications (ICIEA): Auckland, 15-17 June 2015, Piscataway, NJ: IEEE Communications Society, 2015, p. 990-995, article id 7334252Conference paper (Refereed)
    Abstract [en]

    Robustness, real-time properties and resource efficiency are key properties to embedded devices of the CPS/IoT era. In this paper we propose a language approach RTFMcore, and show its potential to facilitate the development process and provide highly efficient and statically verifiable implementations. Our programming model is reactive, based on the familiar notions of concurrent tasks and (single-unit) resources. The language is kept minimalistic, capturing the static task, communication and resource structure of the system. Whereas C-source can be arbitrarily embedded in the model, and/or externally referenced, the instep to mainstream development is minimal, and a smooth transition of legacy code is possible. A prototype compiler implementation for RTFM-core is presented. The compiler generates C-code output that compiled together withtheRTFM-kernelprimitivesrunsonbaremetal.TheRTFMkernel guarantees deadlock-lock free execution and efficiently exploits the underlying interrupt hardware for static priority scheduling and resource management under the Stack Resource Policy. This allows a plethora of well-known methods to static verification (response time analysis, stack memory analysis, etc.) to be readily applied. The proposed language and supporting tool-chain is demonstrated by showing the complete process from RTFM-core source code into bare metal executables for a lightweight ARM-Cortex M3 target.

  • 7.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Pereira, David J.
    ISEP, Instituto Superior de Engenharia do Porto.
    Pinho, Luis Miguel
    ISEP, Instituto Superior de Engenharia do Porto.
    Well formed Control-flow for Critical Sections in RTFM-core2015In: IEEE International Conference on Industrial Informatics: INDIN 2015, Cambridge, UK, July 22-24, 2015. Proceedings, Piscataway, NJ: IEEE Communications Society, 2015, p. 1438-1445, article id 7281944Conference paper (Refereed)
    Abstract [en]

    The mainstream of embedded software development as of today is dominated by C programming. To aid the development, hardware abstractions, libraries, kernels and lightweight operating systems are commonplace. Such kernels and operating systems typically impose a thread based abstraction to concurrency. However, in general thread based programming is hard, plagued by hazards of race conditions and dead-locks. For this paper we take an alternative outset in terms of a language abstraction, RTFM-core, where the system is modelled directly in terms of tasks and resources. In compliance to the Stack Resource Policy (SRP) model, the language enforces (well formed) LIFO nesting of claimed resources, thus SRP based analysis and scheduling can be readily applied. For the execution onto bare-metal single core architectures, the rtfm-core compiler performs SRP analysis on the model, and render an executable that is deadlock free and (through RTFM-kernel primitives) exploits the underlying interrupt hardware for efficient scheduling. The RTFM-core language embeds C-code and links to C-object files and libraries, and is thus applicable to the mainstream of embedded development. However, while the language enforces well formed resource management, control flow in the embedded C-code may violate the LIFO nesting requirement, thus correctness is left with the programmer to ensure well formed nesting (through restricted control flow). In this paper we address this issue by lifting a subset of C into the RTFM-core language allowing arbitrary control flow at the model level. In this way well formed LIFO nesting can be enforced, and models ensured to be correct by construction. We demonstrate the feasibility trough a prototype implementation in the rtfm-core compiler. Additionally, we develop a set of running examples, and show in detail how control flow is handled at compile time and during run-time execution.

  • 8.
    Lindgren, Per
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Vyatkin, Valeriy
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Pereira, David J.
    ISEP, Instituto Superior de Engenharia do Porto.
    Pinho, Luis Miguel
    ISEP, Instituto Superior de Engenharia do Porto.
    A Real-Time Semantics for the IEC 61499 standard2015In: Proceedings of 2015 IEEE 20th International Conference on Emerging Technologies & Factory Automation (ETFA 2015): Luxembourg, 8-11 Sept. 2015, Piscataway, NJ: IEEE Communications Society, 2015, article id 7301558Conference paper (Refereed)
    Abstract [en]

    The IEC 61499 standard provides an executable model for distributed control systems in terms of interacting function blocks. However, the current IEC 61499 standard lacks appropriate timing semantics for the specification of timing requirements, reasoning on timing properties at the model level, and for the timing verification of a specific deployment. In this paper we address this fundamental shortcoming by proposing Real-Time-4-FUN, a real-time semantics for IEC 61499. The key property is the preservation of non-determinism, allowing us to reason on (and verify) timing properties at the model level without assuming any specific scheduling policy or stipulating specific order of execution for the deployment. This provides for a clear separation of concerns, where the designer can focus on properties of the application prior to, and separately from, deployment verification. The proposed timing semantics is backwards compatible to the current standard, thus allow for reuse of existing designs. The transitional property allows timing requirements to propagate to downstream sub-systems, and can be utilized for scheduling both at device and network level. Based on a translation to RTFM-tasks and resources, IEC 61499 the models can be analyzed, compiled and executed. As a proof of concept the timing semantics has been experimentally implemented in the RTFM-core language and the accompanying (thread based) RTFM-RT run-time system.

  • 9.
    Lindner, Andreas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    RTFM-RT: a threaded runtime for RTFM-core towards execution of IEC 614992015In: Proceedings of 2015 IEEE 20th International Conference on Emerging Technologies & Factory Automation (ETFA 2015): Luxembourg, 8-11 Sept. 2015, Piscataway, NJ: IEEE Communications Society, 2015, article id 7301501Conference paper (Refereed)
    Abstract [en]

    The IEC 61449 standard provides an outset for designing and deploying distributed control systems. Recently, a mapping from IEC 61499 to the RTFM-kernel API has been presented. This allows predictable real-time execution of IEC 61499 applications on light-weight single-core platforms. However, integrating the RTFM-kernel (bare-metal runtime) into potential deployments requires developing device drivers, protocol stacks, and the like. For this presentation, we apply the mapping from IEC 61499 to the RTFM-MoC task and resource modelimplementedbytheRTFM-corelanguage.Thecompilation from RTFM-core can be targeted to both, RTFM-kernel and the introduced runtime system RTFM-RT. In this paper, we detail thegenericRTFM-RTruntimearchitecture,whichallowsRTFMcore programs to be executed on top of thread based environments. Furthermore, we discuss our implementation regarding scheduling specifics of Win32 threads (Windows) and Pthreads (Linux and Mac OS X). Using our RTFM-RT implementation for deployment,predictableIEC61499executiontogetherwithaccess to abovementioned operating system functions are achieved. For further developments, we discuss the needed scheduling options to achieve hard real-time and analysis required to eliminate deadlocks.

  • 10.
    Lindner, Marcus
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    RTFM-core: Course in Compiler Construction2014In: Proceedings of the WESE'14: Workshop on Embedded and Cyber-Physical Systems Education, New York: ACM Digital Library, 2014, article id 4Conference paper (Refereed)
    Abstract [en]

    The course in Compiler Construction is part of the ComputerScience second cycle curriculum at Lulea Universityof Technology (LTU). Starting this year, the course is nowto be given by the Embedded Systems group at LTU. Thispaper outlines the course syllabus, and its relation to CPS/IoT and embedded systems in general. In particular, thecourse will now introduce domain specic language designwith the outset from the RTFM-core language. Studentswill be exposed to design choices for the language, spanningfrom programming model, compiler design issues, backendtools and even run-time environments. The intention is togive a holistic perspective, and motivate the use of compilationtechniques towards robust, ecient and veriable (embedded)software. Of course, developing basic skills will notbe overlooked, and as part of the laboratory assignments,students will extend the minimalistic Object Oriented languageRTFM-cOOre and develop the compiler accordinglytargeting the RTFM-core language as an intermediate representation.As the RTFM-core/-cOOre compilers are implementedunder OCaml/Menhir, the students will be exposedto the advantages of functional languages in the contextof compiler construction. However, for their own developmentthey may choose alternative design tools and languages(such as ANTLR/Java). This will give us the opportunityto review and correlate achievements and eciencyto the choice of tools and languages and be an outset forfuture course development.

  • 11.
    Lindner, Marcus
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    RTFM-core: course in compiler construction2016In: The SIGBED Review, ISSN 1551-3688, Vol. 14, no 1, p. 29-36Article in journal (Refereed)
    Abstract [en]

    The course in Compiler Construction is part of the Computer Science masters program at Luleå University of Technology (LTU). Since the fall of 2014, the course is given by the Embedded Systems group. This paper outlines the course syllabus and its relation to CPS/IoT and embedded systems in general. In particular, the course introduces domain specific language design with the outset from the imperative RTFM-core language. Students are exposed to design choices for the language, spanning from programming model, compiler design issues, back-end tools, and even runtime environments. The intention is to give a holistic perspective and motivate the use of compilation techniques towards robust, efficient, and verifiable (embedded) software. Of course, developing basic skills is not overlooked and as part of the laboratory assignments, students extend the min-imalistic Object Oriented language RTFM-cOOre and develop the compiler accordingly targeting the RTFM-core language as an intermediate representation. As the RTFM-core/-cOOre compilers are implemented using OCaml/Men-hir, the students are also exposed to functional languages and to their advantages in the context of compiler construction. However, for their own development they may choose alternative design tools and languages. This gives us the opportunity to review and correlate achievements and efficiency to the choice of tools and languages and it is an outset for future course development.

  • 12.
    Lindner, Marcus
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindner, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lindgren, Per
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Safe tasks: run time verification of the RTFM-lang model of computation2016In: 2016 IEEE 21st International Conference on Emerging Technologies and Factory Automation (ETFA): Berlin, 6-9 Sept. 2016, Piscataway, NJ: IEEE conference proceedings, 2016, article id 7733550Conference paper (Refereed)
    Abstract [en]

    Embedded systems for critical applications are typicallyspecified with requirements on predictable timing andsafety. While ensuring predictable timing, the RTFM-lang (Real-Time For the Masses) model of computation (MoC) currentlylacks memory access protection among real-time tasks. In thispaper, we discuss how to safely verify task execution given aspecification using the RTFM-MoC. Furthermore, an extensionto the RTFM-core infrastructure is outlined and tested with usecases of embedded development. We propose a method for runtime verification exploiting memory protection hardware. Forthis purpose, we introduce memory resources to the declarativelanguage RTFM-core allowing compliance checks. As a proofof concept, compiler support for model analysis and automaticgeneration of run time verification code is implemented togetherwith an isolation layer for the RTFM-kernel. With this verificationfoundation, functional run time checks as well as furtheroverhead assessments are future research questions.

1 - 12 of 12
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