Real Time Ethernet

Real Time Ethernet (RTE) refers to a set of protocols and technologies designed to enable real-time communication and data exchange over Ethernet networks. Real Time Ethernet plays a crucial role in ensuring timely and deterministic transmission of data between various devices, such as sensors, actuators, controllers, and supervisory systems. Traditional Ethernet, as defined in IEEE 802.3, is non-deterministic and unsuitable for strict real-time industrial applications due to its random delays and potential transmission failures. To overcome this limitation, Industrial Ethernet has been developed to incorporate real-time capabilities into a single-network solution.

Industrial automation systems often require precise timing and synchronization for tasks such as control loops, motion control, and process monitoring. RTE protocols address these requirements by providing mechanisms for prioritizing traffic, minimizing latency, and ensuring consistent communication performance. RTE solutions prioritize deterministic communication by introducing standardized prioritization and user-defined priority levels for traffic.

RTE can support both standard Ethernet communication and real-time requirements concurrently. This allows for the integration of traditional office IT networks with industrial control systems, leading to simplified network architectures and reduced infrastructure costs.

Determinism and Real-time Capabilities

RTE protocols introduce and ensure determinism, ensuring that messages are delivered within a guaranteed time frame. This is crucial for applications where timing is critical, such as in motion control systems, process automation, robotics or safety mechanisms.

Redundancy and Reliability

High availability and reliability are achieved through redundancy mechanisms such as Parallel Redundancy Protocol (PRP) and High-availability Seamless Redundancy (HSR). These protocols allow for the simultaneous transmission of duplicate frames over separate paths, ensuring that a single point of failure does not disrupt communication. In this way, Real Time Ethernet technologies increase the reliability and fault tolerance of the network while ensuring continuous operation by automatically switching to backup paths or devices in the event of network failures or component malfunctions.

Time Synchronization

Precise time synchronization across devices is a cornerstone of Real Time Ethernet. Protocols like IEEE 1588 Precision Time Protocol (PTP) are used to synchronize the clocks of all devices on the network to a high degree of accuracy, often within sub-microseconds. This synchronization is vital for coordinated actions and for maintaining the sequence of operations across distributed systems. Precise synchronization is essential for maintaining temporal relationships between distributed control systems and synchronizing actions across multiple devices.

Compatibility and Interoperability

Real Time Ethernet must interoperate with both current and legacy systems while providing predictable performance and maintainability. This includes physical compatibility, low-level transport protocols, and interoperability at higher levels of the OSI model. Ensuring security from both external intrusions and unauthorized internal use is also a critical feature. Real Time Ethernet protocols seamlessly integrate with standard Ethernet technology and infrastructure, allowing for interoperability with existing IT networks. Integration with standard Ethernet simplifies deployment, maintenance, and management of industrial automation systems while leveraging the benefits of Ethernet technology.

Diagnostics and Monitoring

RTE protocols offer diagnostic and monitoring capabilities to facilitate troubleshooting, performance analysis, and system optimization. Diagnostic tools provide insights into network health, traffic patterns, and device status, enabling proactive maintenance and rapid fault detection.

These technical features collectively enable Real Time Ethernet to meet the stringent requirements of industrial automation applications, including high reliability, low latency, and deterministic communication. These features ensure that RTE can provide the reliable, deterministic communication necessary for the precise control and coordination of industrial processes.

The protocols of RTE encompass a range of standards designed to meet the stringent timing requirements of industrial automation and communication.

PROFINET (Process Field Net)

PROFINET is a widely adopted RTE protocol in industrial automation. It supports both real-time communication and standard TCP/IP communication, allowing for seamless integration with existing Ethernet infrastructure. PROFINET offers features such as isochronous real-time communication, prioritized messaging, and redundancy for enhanced reliability. It provides different communication modes, including RT (Real-Time), IRT (Isochronous Real-Time), and RT-IRT (Combined Real-Time and Isochronous Real-Time).

EtherCAT (Ethernet for Control Automation Technology)

EtherCAT is an open Real Time Ethernet protocol standardized by the EtherCAT Technology Group (ETG). It employs a unique "processing on the fly" approach, where each network node processes data as it passes through, enabling very low communication latencies and high synchronization accuracy. It is a MAC-layer protocol that can support up to 65,535 devices and offers top-notch bandwidth utilization. It also supports flexible topologies, including line, ring, and tree structures, making it suitable for various industrial applications. It offers features such as distributed clock synchronization, hot plugging of devices, and support for mixed cycle times.

EtherNet/IP

It extends standard Ethernet to support real-time control and information exchange in automation systems. It is based on the Common Industrial Protocol (CIP) and allows for seamless integration with other CIP-based networks. EtherNet/IP supports both explicit messaging (client-server communication) and implicit messaging (I/O data exchange), providing flexibility for different types of applications. It offers features such as device-level ring (DLR) for network redundancy, quality of service (QoS) for prioritizing traffic, and object-oriented data representation. It uses standard Ethernet physical, data link, network, and transport layers for communication.

Modbus TCP/IP

Modbus TCP/IP is a variant of the Modbus protocol, a widely used serial communication protocol in industrial automation. It enables Modbus communication over Ethernet networks, providing a cost-effective solution for real-time data exchange in industrial applications. It supports controller-device communication model, where a controller initiates requests to read or write data from/to devices connected to the network. It offers features such as broadcast messaging, multiple register types (coil, discrete input, input register, holding register), and error detection through CRC (Cyclic Redundancy Check).

Ethernet POWERLINK

Ethernet POWERLINK is a RTE protocol that prioritizes time-critical data and ensures deterministic communication. It relies on a controller or managing node for successful operation and has limited scalability due to manual configuration of 8-bit addresses for devices connected on the network.

These protocols serve as the backbone for real-time and deterministic communication in industrial automation, enabling precise control, synchronization, and data exchange between devices in manufacturing, process control, and other industrial applications. Each protocol has its own strengths and suitability for specific use cases, allowing system designers to choose the most appropriate solution based on their requirements.

RTE systems are generally categorized into two main sub-categories: hard real-time (HRT) and soft real-time (SRT), each catering to specific timing requirements and performance characteristics. These categories are distinguished by the severity of the consequences that can result from data not being processed or delivered within the required time constraints.

Hard Real-Time (HRT) 

Hard real-time systems are those in which the failure to meet timing constraints can lead to catastrophic events. In the context of industrial automation, this could mean the failure of a critical component of a manufacturing process, leading to safety hazards, equipment damage, or significant financial loss. These systems are designed to meet strict timing constraints, ensuring that time-critical operations, such as control loops and motion control, are executed reliably and predictably. HRT systems require strict guarantees on the determinism and timeliness of data delivery. The operation must be correct and occur within a precise time frame, often in the order of milliseconds or less.

Soft Real-Time (SRT)

This system provides a level of timing predictability and responsiveness that meets the requirements of most real-time applications but allows for occasional deviations from strict timing constraints. While soft real-time systems prioritize timely execution of tasks, they may tolerate occasional delays or variations in response times, as long as overall performance remains acceptable for the application. The consequences of missing a deadline are less severe than with HRT systems.  Soft real-time Ethernet protocols focus on achieving high throughput, low latency, and reduced jitter, without imposing the same level of strict timing requirements as hard real-time systems. SRT systems can tolerate some delays and do not necessarily require guarantees that all deadlines will be met.

Time-Sensitive Networking (TSN)

It is an evolving set of standards aimed at enhancing Ethernet with deterministic and real-time capabilities to support a broad range of applications. TSN provides a new route to Real Time Ethernet by offering features such as deterministic communication, precise time synchronization, and traffic shaping over standard Ethernet networks. TSN standards define mechanisms for prioritizing traffic, scheduling transmission, and ensuring bounded latency, thereby supporting both hard and soft real-time requirements in diverse industrial applications.

The categorization of RTE is based on the criticality of the timing requirements and the consequences of failing to meet these requirements. It also provides flexibility in meeting different levels of timing requirements and performance expectations in industrial automation and communication systems. Depending on the specific application and its criticality, designers can choose the appropriate category of Real Time Ethernet to ensure optimal system behavior and reliability.

Compared to the fieldbus technologies that previously characterized the landscape of industrial communication, RTE offers several advantages:

Enhanced Performance

RTE protocols provide optimized performance for industrial automation tasks, delivering high throughput, minimal jitter, and consistent communication performance even under heavy network loads.

Cost-Effectiveness

By leveraging standard Ethernet hardware and technologies, RTE can offer cost savings in terms of both initial deployment and ongoing maintenance. The use of a unified network infrastructure reduces the need for specialized equipment and cabling, while also simplifying network management and troubleshooting. Furthermore, the high efficiency and reliability of RTE networks can lead to reduced operational costs over time.

Advanced Diagnostics and Monitoring

RTE protocols offer diagnostic tools and monitoring capabilities to facilitate troubleshooting, performance analysis, and proactive maintenance of industrial networks, improving system reliability and uptime.

Low Latency

Real Time Ethernet protocols minimize communication latency, enabling rapid response times for critical control and monitoring tasks. Low latency is essential for real-time control systems, motion control, and high-speed data acquisition applications. This is also one of reasons why it provides enhanced performance and why it is very efficient.

Futureproofing

RTE protocols, such as those based on emerging standards like Time-Sensitive Networking (TSN), offer future-proofing capabilities by incorporating technologies and features to support evolving industrial automation requirements and standards.

Integration along the entire automation pyramid: Real Time Ethernet simplifies networking across the automation pyramid by providing deterministic, low-latency communication between different system levels—from field devices (sensors/actuators) to controllers and up to enterprise IT systems. RTE protocols ensure synchronized data exchange, enabling precise control and monitoring in real-time. Its standardized Ethernet-based infrastructure allows integration of diverse devices and systems on a single network, eliminating the need for protocol converters and reducing the complexity of connecting operational technology (OT) with IT. This interoperability streamlines data flow and enhances system-wide visibility, making it easier to network all levels efficiently.

As a market leader Hilscher offers a wide range of products for industrial communication in RTE networks. The netX technology and the multiprotocol-capable SoCs (System on Chips) based on it are at the forefront. These can be integrated into industrial components - such as controllers, sensors or actuators - as highly integrated communication interfaces. Thanks to the associated firmware, which can be loaded onto the chip as required for the needed protocol stack, Hilscher supports component manufacturers and automation specialists in the development of flexible solutions for use in a wide variety of RTE networks – for example for PROFINET, EtherCAT, EtherNet/IP, CC-Link IE or Ethernet POWERLINK.

Based on the netX communication controllers, Hilscher developed different embedded modules and the PC cards of the cifX family (which are available in all common form factors - from PCI and PCIe to the smallest multiprotocol-capable PC cards on the automation market in M.2 format). These communication interfaces already include the necessary chip peripherals and are therefore faster to integrate.

In addition, gateways, switches and network and communication diagnostic devices support the smooth operation of fieldbus networks.

Next to RTE systems, Hilscher's components for industrial communication networks also support the most common fieldbus protocols - such as PROFIBUS, Modbus, CC-Link or DeviceNet.

The portfolio is rounded off by the netFIELD ecosystem for Managed Industrial IoT. From the edge gateway to the cloud platform for centralized container management, netFIELD offers everything you need to develop modern applications in line with Industry 4.0.