Modbus Extension Server Implementation for BIoT-Enabled Smart Switch Embedded System Device.

The industrial control and automation sector has invested in the development and standardization of new wireless (WirelessHART, ISA 100.11a, and WIA-PA) and wired (Profibus/Profinet, Modbus, and LonWORK) solutions aimed at automating processes to support standard monitoring and control functions from the perspective of addressing critical applications, as well as those integrated within the Building Internet of Things (BIoT) concept. Distributed data acquisition and control systems allow modern installations to monitor and control devices remotely. Various network protocols have been proposed to specify communication formats between a client/gateway and server devices, with Modbus being an example that has been widely implemented in the latest industrial electrical installations. The main contribution made in this paper concerns the completion of the Modbus Extension (ModbusE) specifications for the server station in the classical Modbus communication architecture, as well as their implementation and testing in an STM32F4 kit. A general-purpose control architecture is proposed for BIoT sector, comprising both intelligent touch switches and communication protocols of which the Modbus protocol is used extensively for the monitoring and control part, especially between clients, smart switches, and devices. The specific contributions concern the presentation of a scientific and practical implementation of improved specifications and their integration as software modules on ModbusE protocol server stations. A client station with a VirtualComm USB PC connection is also implemented in the lab to test the operation of the proposed server with specific Modbus applications.

An Overview of the nMPRA and nHSE Microarchitectures for Real-Time Applications.

In the context of real-time control systems, it has become possible to obtain temporal resolutions of microseconds due to the development of embedded systems and the Internet of Things (IoT), the optimization of the use of processor hardware, and the improvement of architectures and real-time operating systems (RTOSs). All of these factors, together with current technological developments, have led to efficient central processing unit (CPU) time usage, guaranteeing both the predictability of thread execution and the satisfaction of the timing constraints required by real-time systems (RTSs). This is mainly due to time sharing in embedded RTSs and the pseudo-parallel execution of tasks in single-processor and multi-processor systems. The non-deterministic behavior triggered by asynchronous external interrupts and events in general is due to the fact that, for most commercial RTOSs, the execution of the same instruction ends in a variable number of cycles, primarily due to hazards. The software implementation of RTOS-specific mechanisms may lead to significant delays that can affect deadline requirements for some RTSs. The main objective of this paper was the design and deployment of innovative solutions to improve the performance of RTOSs by implementing their functions in hardware. The obtained architectures are intended to provide feasible scheduling, even if the total CPU utilization is close to the maximum limit. The contributions made by the authors will be followed by the validation of a high-performing microarchitecture, which is expected to allow a thread context switching time and event response time of only one clock cycle each. The main purpose of the research presented in this paper is to improve these factors of RTSs, as well as the implementation of the hardware structure used for the static and dynamic scheduling of tasks, for RTOS mechanisms specific to resource sharing and intertask communication.

Experimental Implementation and Performance Evaluation of an IoT Access Gateway for the Modbus Extension.

This paper presents the relevant aspects regarding the experimental implementation and performance evaluation of an Internet of things (IoT) gateway for the Modbus extension. The proposed Modbus extension specifications are extended by defining the new optimized message format, and the structure of the acquisition cycle for obtaining a deterministic temporal behavior and solutions are presented for the description of devices at the MODBUS protocol level. Three different implementations are presented, and the Modbus extension's performance is validated regarding the efficiency in the use of the acquisition cycle time. The software and hardware processing time and the importance and effect of the various components are analyzed and evaluated. They all support the implementation of an Internet of things gateway for Modbus extension. This paper introduces solutions for the structure of the acquisition cycle to include other valuable extensions, discusses the performance of a real implementation in the form of a gateway, adds new features to the Modbus extension specification, and strengthens some of the existing ones. In accordance with the novelty and contribution of this paper to the field of local industrial networks, the results obtained in the analysis, testing, and validation of the Modbus extension protocol refer to the extending of the Modbus functions for industrial process monitoring and control management.