AV Technologie und ihre Nutzung in einem multifunktionalen Netz zur Automatisierung, zur Videoübertragung und zum Energiemanagement

Ethernet ist die Technologie, auf der heute fast alle zukunftsgerichteten Kommunikationssysteme beruhen. Leider greifen die meisten Gruppen dabei auf die Optimierung ihrer eigenen Bedürfnisse zurück und machen somit einen übergreifenden Ansatz schwer. IEEE 802.1 ist die Gruppe, die am ehesten die verschiedenen Anwendungen zusammenführen kann. Im Bereich der Echtzeitkommunikation liegt von der Audio-Video-Bridging Taskgroup nun eine erste Reihe von Standards vor, die ein Kandidat für eine umfassende Echtzeitlösung ist. Allerdings sind noch Erweiterungen erforderlich, um die Latenz der Frames zu verkürzen, die Verfügbarkeit zu erhöhen und Lastsituationen sicher zu beherrschen

A Hardware Independent Real-time Ethernet for Motion Control Systems

Ethernet for Manufacture Automation Control (EtherMAC) is a new kind of real-time Ethernet used in motion control systems. It adopts a line topology with a standard industrial computer based master node and field-programmable-gate-array based slave nodes. EtherMAC employs one slave node to manage cycle communication and clock synchronization, so the real-time demand for its master node can be greatly reduced and dedicated hardware is no longer mandatory. Its distributed clock compensation mechanism can get synchronization accuracy in nanosecond order. The advantages of industrial computer and field programmable-gate-array are combined with EtherMAC, so that high control performance can be achieved

Characterization of communication channels in terms of traffic and network architecture: a review

Software tools face accessibility and availability limitations in monitoring and industrial control processes when communications are affected by long distances. Likewise, real-time answers and stability are also limited by the traffic conditions in LAN network. Ethernet networks are widely-used in industrial communications due to high performance in multiswitch configuration. However, they are not the most appropriate solution for real-time applications, given the difficulty in measuring response times in data transmission, and even more so when the network topologies are different and traffic levels are permanently varying. This paper presents a review of the characterization of communication channels in terms of traffic and network architecture,  identifying  unexplored  areas  and  promoting  new alternatives that may be easily adopted by the industrial sector.  In  conclusion,  a  technique  integrated  by  architecture  and  traffic  characteristics  in  network  analysis may  performance  in  heterogeneous  systems  for  industrial applications via web.Las herramientas de software presentan limitaciones de acceso y disponibilidad en los procesos de monitoreo y control industrial, cuando las comunicaciones son afectadas por grandes distancias. Asimismo, las respuestas en tiempo real y la estabilidad también son limitadas por las condiciones de tráfico en redes LAN. Es conocido que las redes Ethernet son ampliamente usadas en comunicaciones industriales por su alto rendimiento en configuraciones de switches. Sin embargo, no han sido la solución adecuada para aplicaciones en tiempo real, dado el inconveniente de medir el tiempo de respuesta en la transmisión de datos, y más aún, cuando las topologías de las redes son diferentes y los niveles de tráfico varían permanentemente. En este artículo, se presenta una revisión del estado del arte sobre la caracterización de canales de comunicación en términos de tráfico y arquitectura de la red, donde se determinan campos que aún quedan abiertos en esta área del conocimiento, y se inquieta hacia nuevas alternativas que puedan ser fácilmente adoptables por el sector industrial. Como conclusión, se establece que una técnica integrada por la arquitectura y las características del tráfico en el análisis de redes mejora las perspectivas de rendimiento en sistemas heterogéneos para aplicaciones industriales vía web

Application of Ethernet Powerlink for communication in a Linux RTAI open CNC control system

In computerized numerical control (CNC) systems, the communication bus between the controller and axis servo drives must offer high bandwidth, noise immunity, and time determinism. More and more CNC systems use real-time Ethernet protocols such as Ethernet Powerlink (EPL). Many modern controllers are closed costly hardware-based solutions. In this paper, the implementation of EPL communication bus in a PC-based CNC system is presented. The CNC system includes a PC, a software CNC controller running under Linux Real-Time Application Interface real-time operating system and servo drives communicating via EPL. The EPL stack was implemented as a real-time kernel module. Due to software-only implementation, this system is a cost-effective solution for a broad range of applications in machine control. All software systems are based on GNU General Public License or Berkeley Software Distribution licenses. Necessary modifications to the EPL stack, Linux configurations, computer basic input/output system, and motherboard configurations were presented. Experimental results of EPL communication cycle jitter on three different PCs were presented. The results confirm good performance of the presented system

A Comprehensive Review on Time Sensitive Networks with a Special Focus on Its Applicability to Industrial Smart and Distributed Measurement Systems

The groundbreaking transformations triggered by the Industry 4.0 paradigm have dramati-cally reshaped the requirements for control and communication systems within the factory systems of the future. The aforementioned technological revolution strongly affects industrial smart and distributed measurement systems as well, pointing to ever more integrated and intelligent equipment devoted to derive accurate measurements. Moreover, as factory automation uses ever wider and complex smart distributed measurement systems, the well-known Internet of Things (IoT) paradigm finds its viability also in the industrial context, namely Industrial IoT (IIoT). In this context, communication networks and protocols play a key role, directly impacting on the measurement accuracy, causality, reliability and safety. The requirements coming both from Industry 4.0 and the IIoT, such as the coexistence of time-sensitive and best effort traffic, the need for enhanced horizontal and vertical integration, and interoperability between Information Technology (IT) and Operational Technology (OT), fostered the development of enhanced communication subsystems. Indeed, established tech-nologies, such as Ethernet and Wi-Fi, widespread in the consumer and office fields, are intrinsically non-deterministic and unable to support critical traffic. In the last years, the IEEE 802.1 Working Group defined an extensive set of standards, comprehensively known as Time Sensitive Networking (TSN), aiming at reshaping the Ethernet standard to support for time-, mission-and safety-critical traffic. In this paper, a comprehensive overview of the TSN Working Group standardization activity is provided, while contextualizing TSN within the complex existing industrial technological panorama, particularly focusing on industrial distributed measurement systems. In particular, this paper has to be considered a technical review of the most important features of TSN, while underlining its applicability to the measurement field. Furthermore, the adoption of TSN within the Wi-Fi technology is addressed in the last part of the survey, since wireless communication represents an appealing opportunity in the industrial measurement context. In this respect, a test case is presented, to point out the need for wirelessly connected sensors networks. In particular, by reviewing some literature contributions it has been possible to show how wireless technologies offer the flexibility necessary to support advanced mobile IIoT applications

Low Latency Audio Processing

PhDLatency in the live audio processing chain has become a concern for audio engineers and system designers because significant delays can be perceived and may affect synchronisation of signals, limit interactivity, degrade sound quality and cause acoustic feedback. In recent years, latency problems have become more severe since audio processing has become digitised, high-resolution ADCs and DACs are used, complex processing is performed, and data communication networks are used for audio signal transmission in conjunction with other traffic types. In many live audio applications, latency thresholds are bounded by human perceptions. The applications such as music ensembles and live monitoring require low delay and predictable latency. Current digital audio systems either have difficulties to achieve or have to trade-off latency with other important audio processing functionalities. This thesis investigated the fundamental causes of the latency in a modern digital audio processing system: group delay, buffering delay, and physical propagation delay and their associated system components. By studying the time-critical path of a general audio system, we focus on three main functional blocks that have the significant impact on overall latency; the high-resolution digital filters in sigma-delta based ADC/DAC, the operating system to process low latency audio streams, and the audio networking to transmit audio with flexibility and convergence. In this work, we formed new theory and methods to reduce latency and accurately predict latency for group delay. We proposed new scheduling algorithms for the operating system that is suitable for low latency audio processing. We designed a new system architecture and new protocols to produce deterministic networking components that can contribute the overall timing assurance and predictability of live audio processing. The results are validated by simulations and experimental tests. Also, this bottom-up approach is aligned with the methodology that could solve the timing problem of general cyber-physical systems that require the integration of communication, software and human interactions