RTFM-core: Language and implementation

2015 IEEE 20th Conference on Emerging Technologies &Amp; Factory Automation (ETFA)

et al. 2015

Self Cite

Abstract-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.

Section: ) Rtfm Model Of Computationmentioning

confidence: 99%

Section: A Permissible Execution Windowmentioning

confidence: 99%

A real-time semantics for the IEC 61499 standard

2015 IEEE 20th Conference on Emerging Technologies &Amp; Factory Automation (ETFA)

et al. 2015

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“…The RTFM-core language is based on the notions of tasks and resources in correspondence to the Stack Resource Policy (SRP), for a detailed description on the original work on -core we refer the reader to [5] and the upcoming [6]. Here we give a brief overview.…”

Section: Rtfm-corementioning

confidence: 99%

Well-formed control flow for critical sections in RTFM-core

2015 IEEE 13th International Conference on Industrial Informatics (INDIN)

et al. 2015

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Abstract-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.

“…That way, programs of our task based model, written in RTFM-core [5], can be executed on mainstream and widespread thread based operating systems and libraries. RTFM-kernel [6] is another execution environment implementing the RTFM-MoC and aiming at highly efficient real-time execution on baremetal.…”

Section: Introductionmentioning

confidence: 99%

RTFM-RT: A threaded runtime for RTFM-core - towards execution of IEC 61499

2015 IEEE 20th Conference on Emerging Technologies &Amp; Factory Automation (ETFA)

2015

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Abstract-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 model implemented by the RTFM-core language. The compilation from RTFM-core can be targeted to both, RTFM-kernel and the introduced runtime system RTFM-RT. In this paper, we detail the generic RTFM-RT runtime architecture, which allows RTFMcore 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, predictable IEC 61499 execution together with access 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.