111 research outputs found
Supporting internet protocols in master-slave fieldbus networks
In this paper we describe how to integrate Internet Protocols (IP) into a typical hierarchical master-slave fieldbus network, supporting a logical ring token passing mechanism between master stations. The integration of the TCP/IP protocols in the fieldbus protocol rises a number of issues that must be addressed properly. In this paper we particularly address the issues related to the conveyance of IP fragments in fieldbus frames (fragmentation/de-fragmentation) and on how to support the symmetry inherent to the TCP/IP protocols in fieldbus slaves, which lack communication initiative
QoS of IP services in a fieldbus network: on the limitations and possible improvements
This paper focuses on the problem of providing
efficient scheduling mechanisms for IP packets
encapsulated in the frames of a real-time fieldbus network
- the PROFIBUS. The approach described consists on a
dual-stack approach encompassing both the controlrelated
traffic ("native" fieldbus traffic) and the IPrelated
traffic. The overall goal is to maintain the hard
real-time guarantees of the control-related traffic, while
at the same time providing the desired quality of service
(QoS) to the coexistent IP applications. We start to
describe the work which have been up to now carried out
in the framework of the European project RFieldbus
(High Performance Wireless Fieldbus in Industrial
Multimedia-Related Environments - IST-1999-11316).
Then we identify its limitations and point out solutions
that are now being addressed out of the framework of the
above-mentioned European project
Integration of TCP/IP and PROFIBUS protocols
Recent technological developments are pulling
fieldbus networks to support a new wide class of
applications, such as industrial multimedia applications.
These applications are usually supported by the widely
used TCP/IP stack. It is thus essential to provide support
to TCP/IP based applications, in fieldbus networks.
This paper presents an effort that is being carried out
to integrate the TCP/IP and PROFIBUS stacks, in order
to support industrial multimedia applications, whilst
guarantying the timing requirements of control-related
traffic
Position paper on time and event-triggered communication services in the context of e-manufacturing
Modern factories are complex systems where
advances in networking and information technologies are
opening new ways towards higher efficiency. Such move
is being driven by market rules with ever-increasing
competition levels, in search for faster time-to-market,
improved process yield, non-stop operations, flexible
manufacturing and tighter supply-chain coupling. All
these aims present a common requirement, i.e. a realtime
flow of information, from the plant-floor up to the
management, maintenance, suppliers and clients, to
support accurate monitoring and control of the factory.
This stresses the importance achieved by the communication
infrastructure in modern manufacturing industry.
This paper presents the authors view concerning the
current trends in modern factory communication systems.
It addresses the problems of seamlessly integrating
different information flows with diverse requirements,
mainly in terms of timeliness. In this aspect, the debate
between event-triggered and time-triggered communication
is revisited as well as the joint support for both types
of traffic. Finally, a view of where factory communication
systems are moving to is also presented, showing the
impact of open and widely available technologies.FCT. ComissĂŁo Europeia(ARTIST,IST-2001-34820
A Real-Time Service-Oriented Architecture for Industrial Automation
Industrial automation platforms are experiencing a paradigm shift. New technologies are making their way in the area, including embedded real-time systems, standard local area networks like Ethernet, Wi-Fi and ZigBee, IP-based communication protocols, standard service oriented architectures (SOAs) and Web services. An automation system will be composed of flexible autonomous components with plug & play functionality, self configuration and diagnostics, and autonomic local control that communicate through standard networking technologies. However, the introduction of these new technologies raises important problems that need to be properly solved, one of these being the need to support real-time and quality-of-service (QoS) for real-time applications. This paper describes a SOA enhanced with real-time capabilities for industrial automation. The proposed architecture allows for negotiation of the QoS requested by clients from Web services, and provides temporal encapsulation of individual activities. This way, it is possible to perform an a priori analysis of the temporal behavior of each service, and to avoid unwanted interference among them. After describing the architecture, experimental results gathered on a real implementation of the framework (which leverages a soft real-time scheduler for the Linux kernel) are presented, showing the effectiveness of the proposed solution. The experiments were performed on simple case studies designed in the context of industrial automation applications
Current challenges and future trends in the field of communication architectures for microgrids
[EN] The concept of microgrid has emerged as a feasible answer to cope with the increasing number of distributed renewable energy sources which are being introduced into the electrical grid. The microgrid communication network should guarantee a complete and bidirectional connectivity among the microgrid resources, a high reliability and a feasible interoperability. This is in a contrast to the current electrical grid structure which is characterized by the lack of connectivity, being a centralized-unidirectional system. In this paper a review of the microgrids information and communication technologies (ICT) is shown. In addition, a guideline for the transition from the current communication systems to the future generation of microgrid communications is provided. This paper contains a systematic review of the most suitable communication network topologies, technologies and protocols for smart microgrids. It is concluded that a new generation of peer-to-peer communication systems is required towards a dynamic smart microgrid. Potential future research about communications of the next microgrid generation is also identified.This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Regional Development Fund (ERDF) under Grant ENE2015-64087-C2-2. This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under grant BES-2013-064539.Marzal-Romeu, S.; Salas-Puente, RA.; GonzĂĄlez Medina, R.; GarcerĂĄ, G.; Figueres AmorĂłs, E. (2018). Current challenges and future trends in the field of communication architectures for microgrids. Renewable and Sustainable Energy Reviews. 82(2):3610-3622. https://doi.org/10.1016/j.rser.2017.10.101S3610362282
Real-Time Performance of Industrial IoT Communication Technologies: A Review
With the growing need for automation and the ongoing merge of OT and IT,
industrial networks have to transport a high amount of heterogeneous data with
mixed criticality such as control traffic, sensor data, and configuration
messages. Current advances in IT technologies furthermore enable a new set of
automation scenarios under the roof of Industry 4.0 and IIoT where industrial
networks now have to meet new requirements in flexibility and reliability. The
necessary real-time guarantees will place significant demands on the networks.
In this paper, we identify IIoT use cases and infer real-time requirements
along several axes before bridging the gap between real-time network
technologies and the identified scenarios. We review real-time networking
technologies and present peer-reviewed works from the past 5 years for
industrial environments. We investigate how these can be applied to
controllers, systems, and embedded devices. Finally, we discuss open challenges
for real-time communication technologies to enable the identified scenarios.
The review shows academic interest in the field of real-time communication
technologies but also highlights a lack of a fixed set of standards important
for trust in safety and reliability, especially where wireless technologies are
concerned.Comment: IEEE Internet of Things Journal 2023 | Journal article DOI:
10.1109/JIOT.2023.333250
Ethernet - a survey on its fields of application
During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application fieldâs requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal
FTT-Ethernet: A Flexible Real-Time Communication Protocol that Supports Dynamic QoS Management on Ethernet-based Systems
Ethernet was not originally developed to meet the
requirements of real-time industrial automation systems and
it was commonly considered unsuited for applications at the
field level. Hence, several techniques were developed to make
this protocol exhibit real-time behavior, some of them requiring
specialized hardware, others providing soft-real-time guarantees
only, or others achieving hard real-time guarantees with
different levels of bandwidth efficiency. More recently, there has
been an effort to support quality-of-service (QoS) negotiation
and enforcement but there is not yet an Ethernet-based data
link protocol capable of providing dynamic QoS management
to further exploit the variable requirements of dynamic applications.
This paper presents the FTT-Ethernet protocol, which
efficiently supports hard-real-time operation in a flexible way,
seamlessly over shared or switched Ethernet. The FTT-Ethernet
protocol employs an efficient master/multislave transmission
control technique and combines online scheduling with online
admission control, to guarantee continued real-time operation
under dynamic communication requirements, together with data
structures and mechanisms that are tailored to support dynamic
QoS management. The paper includes a sample application,
aiming at the management of video streams, which highlights
the protocolâs ability to support dynamic QoS management with
real-time guarantees
Channel adaptive real-time medium access control protocols for industrial wireless networks
Wireless technology is increasingly finding its way into industrial communication because of the tremendous advantages it is capable of offering. However, the high bit error rate characteristics of wireless channel due to conditions, such as attenuation, noise, channel fading and interference seriously impact the timeliness and reliability guarantee that need to be provided for real-time traffic. Existing wireless protocols either do not adapt well to erroneous channel conditions or do not provide real-time guarantees. The goal of our work is to design and evaluate novel real-time MAC (Medium Access Control) protocols for combined scheduling of periodic and aperiodic messages taking into account the time-varying channel condition.;Our first contribution is the design of a combined scheduling algorithm that exploits both spatial and temporal diversity of the wireless channel through exchange of slots among nodes, to effectively mitigate bursty channel error conditions. Simulation results show that the proposed algorithm achieves significant improvements in message success ratio compared to baseline protocols under a wide range of traffic and channel conditions.;The second contribution assumes a two-level hierarchical network in which nodes are grouped into clusters and the communication occurs within each cluster and across clusters. The goal is to maximize the schedulability of intra- and inter-cluster periodic and aperiodic messages with deadline guarantees. In this context, we propose an Adaptive protocol that maximizes the channel utilization by enabling parallel transmissions in a collision-free manner, in conjunction with the use of the slot-exchange technique to actively combat the erroneous channel conditions. Through simulation studies, we show that the proposed Adaptive protocol achieves significant improvement in packet loss performance compared to the baseline protocols that exploit complete parallelism and full exchange, for a wide range of channel conditions.;The future work includes: (i) Formulation of the MAC scheduling problem to a n-level hierarchical network and developing novel scheduling algorithms (ii) Extending the scheduling problem to account for node mobility and developing mobility-aware MAC protocols
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