70,818 research outputs found
Asynchronous real-time ethernet
The Industrial Ethernet has become a way to build distributed systems in industrial networks which must provide predictable performance and maintainability. Industrial applications require time-critical processing, which can be guaranteed within soft or hard real-time environments, Where applications' responses require deterministic processing time, the hard real-time environment is requested. The Fieldbus protocols are the standard way to connect instruments on the Ethernet-based communication. Fieldbuses require synchronisation and dedicated application-specific integrated circuits, what leaves space for alternate, more common solutions. This thesis presents design, implementation, and evaluation of the novel Real-Time Driver Model asynchronous communication stack called 61850CS API. 61850CS stack is implemented in an intelligent electronic device to enable real-time IEC 61850 GOOSE Ethernet communications in electrical substations. The presented 61850CS implementation enables simultaneous flow of real-time and non-real-time Ethernet traffic over the same physical network interface controller. The same technology supports running arbitrary real-time Ethernet traffic and non real-time Ethernet traffic simultaneously and its implementation is general enough to enable an API use on different architectures and to comply with different industrial Ethernet requirements. And more, since 61850CS doesn't affect CSMA/CD mechanism, it doesn't need any master nodes, which increases the system availability.
The presented solution was implemented as an application programming interface for feeder protection and control (FPC 680) intelligent electronic device relay. Hardware platform for 61850CS was PPC440EPx microcontroller with implemented Linux Real-Time application interface RTOS. The FPC 680 is an IED commercial product by Iskra d.d. which is implemented worldwide in several substations
Asynchronous real-time ethernet
The Industrial Ethernet has become a way to build distributed systems in industrial networks which must provide predictable performance and maintainability. Industrial applications require time-critical processing, which can be guaranteed within soft or hard real-time environments, Where applications' responses require deterministic processing time, the hard real-time environment is requested. The Fieldbus protocols are the standard way to connect instruments on the Ethernet-based communication. Fieldbuses require synchronisation and dedicated application-specific integrated circuits, what leaves space for alternate, more common solutions. This thesis presents design, implementation, and evaluation of the novel Real-Time Driver Model asynchronous communication stack called 61850CS API. 61850CS stack is implemented in an intelligent electronic device to enable real-time IEC 61850 GOOSE Ethernet communications in electrical substations. The presented 61850CS implementation enables simultaneous flow of real-time and non-real-time Ethernet traffic over the same physical network interface controller. The same technology supports running arbitrary real-time Ethernet traffic and non real-time Ethernet traffic simultaneously and its implementation is general enough to enable an API use on different architectures and to comply with different industrial Ethernet requirements. And more, since 61850CS doesn't affect CSMA/CD mechanism, it doesn't need any master nodes, which increases the system availability.
The presented solution was implemented as an application programming interface for feeder protection and control (FPC 680) intelligent electronic device relay. Hardware platform for 61850CS was PPC440EPx microcontroller with implemented Linux Real-Time application interface RTOS. The FPC 680 is an IED commercial product by Iskra d.d. which is implemented worldwide in several substations
Real-time communication over switched ethernet for military applications
Full-Duplex Switched Ethernet is a forecasted new technology
for advanced military aircraft system interconnection. However, it was not originally developed to meet the requirements of real-time communications. Therefore, in this paper, we analyze traffic shaping and a priority handling approach over switched Ethernet to achieve reliable transmission with bounded delays that conform to the real-time constraints, required by military applications
Ethernet та промислові мережі реального часу
У статті розглядається питання перспективності використання стандартів Real-Time Ethernet для передачі даних в мережах реального часу. Висвітлено переваги мереж Ethernet перед традиційними польовими шинами, даний огляд основних стандартів RealTime Ethernet, специфіки їх використання, можливостей.The article discusses the prospects of using standard Real-Time Ethernet for data transmission in real-time networks. The advantages of Ethernet over traditional fieldbus, an overview of the basic standards of RealTime Ethernet, the specifics of their use, functionality
Full duplex switched ethernet for next generation "1553B" -based applications
Over the last thirty years, the MIL-STD 1553B data bus has been used in many embedded systems, like aircrafts, ships, missiles and satellites. However, the increasing number and complexity of interconnected subsystems lead to emerging needs for more communication bandwidth. Therefore, a new interconnection system is needed to overcome the limitations of the MIL-STD 1553B data bus. Among several high speed networks, Full Duplex Switched Ethernet is put forward here as an attractive candidate to replace the MIL-STD 1553B data bus. However, the key argument against Switched Ethernet lies in its non-deterministic behavior that makes it inadequate to deliver hard timeconstrained communications. Hence, our primary objective in this paper is to achieve an accepted QoS level offered by Switched Ethernet, to support diverse "1553B"-based applications requirements. We evaluate the performance of traffic shaping techniques on Full Duplex Switched Ethernet with an adequate choice of service strategy in the switch, to guarantee the real-time constraints required by these specific 1553B-based applications. An analytic study is conducted, using the Network Calculus formalism, to evaluate the deterministic guarantees offered by our approach. Theoretical analysis are then investigated in the case of a realistic "1553B"-based application extracted from a real military aircraft network. The results herein show the ability of profiled Full Duplex Switched Ethernet to satisfy 1553B-like real-time constraints
Ethernet goes real-time: a survey on research and technological developments
Ethernet is the most popular LAN technology. Its low price and robustness, resulting from its
wide acceptance and deployment, has created an eagerness to expand its responsibilities to
the factory-floor, where real-time requirements are to be fulfilled. However, it is difficult to
build a real-time control network using Ethernet, because its MAC protocol, the 1-persistent
CSMA/CD protocol with the BEB collision resolution algorithm, has unpredictable delay
characteristics. Many anticipate that the recent technological advances in Ethernet such as
the emerging Fast/Gigabit Ethernet, micro-segmentation and full-duplex operation using
switches will also enable it to support time-critical applications. This technical report provides
a comprehensive look at the unpredictability inherent to Ethernet and at recent technological
advances towards real-time operation
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 protocol’s ability to support dynamic QoS management with
real-time guarantees
Replacing the Ethernet access mechanism with the real-time access mechanism of Twentenet
The way in which a Local Area Network access mechanism (Medium Access Control protocol) designed for a specific type of physical service can be used on top of another type of physical service is discussed using a particular example. In the example, an Ethernet physical layer is used to provide service to the Twentenet real-time access mechanism. Relevant Ethernet and Twentenet concepts are explained, the approach taken is introduced, and problems encountered, along with the actual synthesis of both networks, are described
Hard Real-Time Networking on Firewire
This paper investigates the possibility of using standard, low-cost, widely used FireWire as a new generation fieldbus medium for real-time distributed control applications. A real-time software subsystem, RT-FireWire was designed that can, in combination with Linux-based real-time operating system, provide hard real-time communication over FireWire. In addition, a high-level module that can emulate Ethernet over RT-FireWire was implemented. This additional module enables existing IP-based real-time communication frameworks to work on top of FireWire. The real-time behavior of RT-FireWire was demonstrated with a simple control setup. Furthermore, an outlook of the future development on RT-FireWire is given
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