Ethernet POWERLINK

Introducing Ethernet POWERLINK

The inception of Ethernet POWERLINK in the early 2000s marked a significant evolution in industrial automation, addressing the critical need for deterministic industrial communication protocols. Traditional Ethernet, while effective for office and commercial networks, fell short in industrial settings due to its non-deterministic nature, which could not guarantee timely data delivery essential for real-time applications. This gap necessitated the development of a system that could meet the stringent timing requirements inherent in sophisticated industrial automation systems. Hence, Ethernet POWERLINK emerged as a solution, developed based on the standard Ethernet IEEE 802.3, engineered to provide real-time capabilities essential for industrial environments. The protocol was introduced by B&R in 2001 and has since been overseen by the Ethernet POWERLINK Standardization Group (EPSG), which was established in June 2003 as an independent association dedicated to furthering its development. Ethernet POWERLINK offers two distinct variants to meet modern control needs. The original variant, Ethernet POWERLINK Standard (EPL), developed by the Ethernet POWERLINK Standardization Group (EPSG), excels in deterministic real-time communication, ensuring precise timing and synchronization across automation components. 

The transition towards deterministic protocols like Ethernet POWERLINK signifies a pivotal advancement in industrial automation, enabling more reliable and efficient control systems. The essence of Ethernet POWERLINK is its capacity to enable precise timing and reliable data transmission, crucial for applications demanding high degrees of timing accuracy and predictability. Furthermore, Ethernet POWERLINK networks are designed to integrate all automation components seamlessly, including PLCs, sensors, I/O modules, motion controllers, safety controls, and HMI systems. This integration capability highlights Ethernet POWERLINK’S role in providing a unified and consistent means for managing communication tasks in automation Its global recognition as an IEC standard and its adoption by leading manufacturers attest to its reliability and effectiveness in meeting the demands of contemporary industrial environments. 

Technical basics

Ethernet POWERLINK operates on master-slave model. This model is pivotal in orchestrating a harmonious and efficient exchange of data within various automation environments. At the heart of this system lies the Managing Node (MN), which could be a programmable logic controller (PLC) or an industrial PC. This central figure assumes the critical role of initiating and coordinating communication across the network. It meticulously determines the timing and sequence of data exchanges, oversees network configuration, and ensures the synchronization of all slave devices to facilitate seamless industrial processes. Complementing the master are the slave devices, also known as Controlled Nodes (CN). These entities obediently respond to the master's commands, each fulfilling a specific function within the network—be it motor control, sensor monitoring, or actuator operation. Slave devices are tasked with transmitting data back to the master in response to its requests or at predetermined intervals during the communication cycle. They dutifully execute the commands relayed by the master and provide necessary status updates or feedback, thereby maintaining the operational integrity of the network. 

Ethernet POWERLINK networks leverage both cyclic and acyclic communication to meet the diverse requirements of industrial automation and control systems. 

  • Cyclic communication 

    Pivotal for the real-time transfer of I/O data between managing nodes (such as PLCs or industrial PCs) and network devices. This process is meticulously orchestrated through a sequence where the managing node dispatches a Start of Cycle (SoC) message to all devices, ensuring their timing is synchronized within specified cycles. The precision of this synchronization is crucial, as it allows for the seamless execution of tasks in environments where timing is of the essence. 

  • Acyclic communication

    Primarily utilized for moving information between Scanners, which are controller side devices, and Adapter devices, which typically represent I/O type devices. It’s used for the transmission of non-time-critical information, such as parameters or diagnostic data, between controllers and devices. This form of communication occurs outside the regular cyclic exchanges, providing flexibility in managing less urgent data without disrupting the deterministic flow of real-time information. 

Ethernet POWERLINK offers an exceptionally flexible network architecture that allows users to choose from a variety of topologies, including star, tree, daisy chain, ring, or a combination of these configurations. This flexibility in network structure means that Ethernet POWERLINK can seamlessly adapt to the specific needs of various industrial environments without requiring extensive configuration. Ethernet POWERLINK ensures ease of use through straightforward wiring and an ability to accommodate flexible topologies, such as line structures, tree structures, or star structures. This flexibility is particularly advantageous for machine and plant manufacturers, who can integrate POWERLINK networks without requiring in-depth networking expertise. Additionally, Ethernet POWERLINK‘s infrastructure allows for the integration of real-time Ethernet communication, making it suitable for applications that demand precise timing and synchronization. 

At its core, the protocol employs a unique frame format that is meticulously structured into header, data, and footer sections. These sections are specifically designed to include fields for addressing, synchronization, and error detection. The addressing mechanism ensures that data packets reach their intended destinations, while the synchronization features guarantee high-precision timing across all devices in the network. Furthermore, Ethernet POWERLINK incorporates Quality of Service (QoS) mechanisms to prioritize critical traffic within the network. This prioritization is essential for ensuring the timely delivery of control data, especially in scenarios where network resources are limited. QoS operates by marking packets to identify service types, then configuring routers to create separate virtual queues for each application based on their priority. This results in bandwidth being reserved for critical applications or websites, thereby enhancing the overall efficiency and reliability of the network. 

Lastly, Ethernet POWERLINK(EPL) is recognized for its cost-effectiveness primarily because it leverages existing Ethernet infrastructure and standard components, employs an open-source protocol, and maintains compatibility with existing software. This combination of characteristics significantly reduces overall costs, making EPL a viable option for many automation and industrial applications. One of the main cost-saving advantages of EPL is its use of existing Ethernet hardware, which translates into a low-cost system relative to its performance. By utilizing pre-existing Ethernet infrastructure, companies can avoid substantial expenses associated with purchasing proprietary hardware. This is in stark contrast to systems that require unique hardware specifically designed for their operation, driving up both initial investment and long-term maintenance costs. 

The components of Ethernet POWERLINK networks

Ethernet POWERLINK utilizes the following hardware and software components to achieve its objectives:  

Hardware components

  1. Ethernet POWERLINK Hubs: Industrial-grade Hubs are crucial for Ethernet POWERLINK networks, providing high-speed data transmission, deterministic behavior, and support for time-critical communication. Designed to withstand extreme environmental conditions, including wide temperature ranges from -40°C to 75°C, as well as vibrations and shocks, ensuring reliable operation under harsh industrial conditions.                                                                                                                                                                                                                                                                                             
  2. Network interfaces: For communication in Ethernet POWERLINK networks, between control units and field devices, these components require reliable communication interfaces. Depending on the application-specific requirements, such as space requirements or integration effort, the network interfaces can be implemented in the form of high-performance SoCs, embedded modules or PC cards.                                                                                                                                                                                                                                                                                                                          
  3. Controllers and devices: The network interconnects various devices such as PLCs, HMIs, drives, sensors, and actuators, enabling them to perform control, monitoring, and automation tasks efficiently. 

Software components

  1. Ethernet POWERLINK protocol stack: The software stack includes multiple layers of the OSI model and is responsible for implementing the communication protocol.                                                                                                                                                                                                                    
  2. Device firmware: Each device within the network runs firmware that incorporates the protocol stack, allowing for the transmission and reception of data packets in accordance with Ethernet POWERLINK specifications.                                                                                                                                          
  3. Configuration and management software: Tools for configuring and managing the network are available, enabling users to set up network parameters, monitor device status, diagnose issues, and conduct maintenance activities. 

Together, these hardware and software components enable Ethernet POWERLINK to deliver reliable, real-time communication capabilities essential for optimizing industrial automation and control systems.  

Advantages of Ethernet POWERLINK for industrial communication

Ethernet POWERLINK offers several advantages in industrial communication, making it a good choice for real-time control and monitoring applications. Some of the key advantages include: 

Deterministic real-time 

Communication with precise timing and synchronization of data exchange. This deterministic nature ensures that events or messages are transmitted within a specified, predictable period, which is crucial for maintaining process stability and efficiency in industrial settings. 

High-speed data transmission 

Facilitates the rapid exchange of control data, sensor readings, and status information between devices. This capability aids in quick decision-making. 

Scalability and flexibility

Enables flexible expansion and integration of new devices as needed, Ethernet POWERLINK supports network topologies like including star, tree, daisy chain, ring, or a combination of these configurations. This adaptability caters to evolving automation needs and optimizes resource utilization, ensuring redundancy and fault tolerance. 

Interoperability and standardization

Adheres to industry standards and specifications to ensure compatibility with a wide range of devices and equipment from different manufacturers. This standardization simplifies the implementation of Ethernet POWERLINK networks in industrial environments, promoting seamless integration. 

Cost-effective

Leverages existing hardware and infrastructure, thereby reducing the need for specialized equipment and lowering deployment and maintenance costs. 

Advanced diagnostic and monitoring capabilities

Manages network traffic efficiently, allocating dedicated timeslots for Isochronous and Asynchronous POWERLINK Data, thereby ensuring optimal performance, and facilitating straightforward network diagnostics. Ethernet POWERLINK employs checksum procedures to continuously verify the completeness of transferred data content and monitors data transfer persistently This feature is particularly beneficial for identifying and resolving issues swiftly, thereby minimizing downtime and enhancing overall system reliability. 

Applications of Ethernet POWERLINK

Ethernet POWERLINK has emerged as a pivotal technology across various sectors, particularly in industrial communication, manufacturing, automation, and production plants. Its applications span from enhancing industrial automation systems to motion control and machine tool operations, underscoring its versatility and critical role in modern industry. 

In the domain of Industrial Automation, Ethernet POWERLINK plays a crucial role by enabling real-time control and monitoring of manufacturing processes. The seamless integration with PLCs, HMIs, sensors, actuators, and robots, streamlines production workflows and boosting overall productivity. The precision in coordination and synchronization it offers is indispensable for maintaining efficient production lines. 

When it comes to Motion Control within manufacturing and automation industries, Ethernet POWERLINK stands out for its capability to ensure high-performance motion control applications. It facilitates synchronized motion control of motors, servos, and other motion devices, which is essential for achieving precise positioning, speed control, and trajectory planning in robotic systems and production lines. 

For machine tools like CNC machines, Ethernet POWERLINK enables precise and responsive control of cutting, milling and machining operations. Its ability to enable real-time industrial communication between machine components ensures accuracy, repeatability, and efficiency in manufacturing processes, which are key factors for competitive advantage in the industry. 

Hilscher's solutions for Ethernet POWERLINK

Hilscher's multiprotocol-capable netX communication controllers and the embedded modules and PC cards based on them serve as flexible and powerful communication interfaces for modern industrial communication networks. By simply loading the specific netX firmware, the components can be integrated into all common Fieldbus or Real-Time Ethernet networks. In addition to Ethernet POWERLINK, they also support standards and technologies such as PROFIBUS, PROFINET, EtherCAT, Modbus or DeviceNet. This means that many different protocols can be mapped using the same hardware, which speeds up the integration process and minimizes costs. Hilscher also offers many other components for industrial communication networks. In addition to gateways, switches and network diagnostic tools, the company also offers a holistic IIoT solution from the sensor to the cloud with its netFIELD ecosystem. 

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