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Industrial Ethernet Facts 2

Industrial Ethernet Facts 2

Product catalog summary

Preface: This document addresses the complexity and lack of transparency in the Industrial Ethernet sector, focusing on five major systems: PROFINET, POWERLINK, EtherNet/IP, EtherCAT, and SERCOS III. It aims to provide a comprehensive and objective comparison of these systems, considering technical, economic, and strategic criteria for long-term investment viability.

Systems Roundup: The document compares five major Industrial Ethernet systems based on technical aspects, standardization status, and market considerations. These systems are selected due to their significant market penetration and suitability for real-time requirements.

Real-Time Performance: Industrial Ethernet protocols employ special measures to achieve real-time performance, crucial for applications requiring precise timing. The document explains the difference between hard and soft real-time requirements and the cycle times needed for various applications.

System Descriptions:

PROFINET: Differentiated into RT and IRT for varying real-time needs, developed by Siemens and PNO. It uses VLAN prioritization for high-priority data and achieves cycle times suitable for Motion Control applications.
POWERLINK: Developed by B&R and managed by EPSG, it is a patent-free, vendor-independent system that uses timeslot and polling procedures for isochronous data transfer, suitable for various automation applications.
EtherNet/IP: Developed by Rockwell Automation and ODVA, it uses standard Ethernet hardware and CIP protocol for flexible communication mechanisms, widely used in the American market.

Investment Viability: The document discusses criteria such as compatibility, electromagnetic compatibility, cabling, hot plugging capability, high availability, and market penetration, which are crucial for assessing the long-term viability of investments in Industrial Ethernet systems.

Performance: It covers theoretically achievable cycle times, communication architecture, network load, and actual performance metrics like jitter and cycle time.

Implementation: Details on master and slave implementation, costs for network components, node connection costs, and operating costs are provided.

Safety Functionality: The document explains network-integrated safety systems, the black channel principle, and how safety systems like CIP Safety, PROFIsafe, openSAFETY, and FSoE work, including their certifications and performance.

Overview of Communication Protocols: This document provides a detailed analysis of various real-time communication protocols used in automation systems, focusing on EtherNet/IP, EtherCAT, SERCOS III, and others. It discusses their operational principles, synchronization methods, and organizational structures.

EtherNet/IP: EtherNet/IP uses TCP for explicit messages and UDP for real-time data due to its lower overhead. It operates in a star topology network with switches to prevent data collisions. It achieves soft real-time performance with cycle times around 10 milliseconds, utilizing CIP Sync and CIP Motion for precise node synchronization.

EtherCAT: Developed by Beckhoff Automation, EtherCAT uses a summation frame method where a single Ethernet frame passes through all nodes, allowing each node to read and insert data on the fly. It requires special hardware for fast processing and supports a logical ring topology. EtherCAT frames contain headers and commands for each node, with synchronization achieved through real-time clocks.

SERCOS III: SERCOS III is a real-time communication standard for digital drive interfaces, using a summation frame method in a daisy chain or ring topology. It supports both real-time and non-real-time channels, with synchronization achieved through a Master Synchronization Telegram. It allows for direct cross-traffic between nodes without routing through the master.

User Organizations: The document outlines the user organizations for each protocol, such as ODVA for EtherNet/IP, ETG for EtherCAT, and sercos International for SERCOS III. These organizations support the development and standardization of their respective technologies.

Legal and Licensing Considerations: It discusses the legal status, rights, and licensing regimes of the user organizations, highlighting the importance of understanding brand rights and patents to avoid legal issues. Membership fees and obligations vary among organizations, with some offering free source code for master and slave implementations.

Investment Viability: The document emphasizes the importance of openness and compatibility with existing application profiles for long-term investment viability. It notes that summation frame protocols are more susceptible to interference than single frame protocols.

Specifications: The document outlines the susceptibility to electromagnetic interference (EMC), electrical contact points, and cabling topology for each system. SERCOS III shows better performance in EMC susceptibility compared to EtherCAT. EtherCAT offers flexible cabling topology with logical ring configurations, while PROFINET and POWERLINK support various topologies including tree and star.

High Availability: POWERLINK is noted for including master and cable redundancy in its specifications, unlike PROFINET and EtherNet/IP, which require special switches for redundancy.

Hot Plugging Capability: PROFINET, POWERLINK, and EtherNet/IP support hot plugging, whereas SERCOS III and EtherCAT have limitations due to their ring topology.

Gigabit Readiness: EtherNet/IP and POWERLINK are software-based and can utilize Gigabit hardware. EtherCAT requires an ASIC redesign for Gigabit scaling, while PROFINET IRT needs hardware redesign, particularly for switches.

International Standards Support: The document lists the IEC 61158 and IEC 61784-2 standards each system complies with, along with their compatibility with Chinese GB standards.

Market Availability: IRT products based on ERTEC technology are widely available, but future compatibility concerns exist due to new ASIC generations.

Performance: The document discusses theoretical cycle times, emphasizing the importance of decentralized control for future scalability. EtherCAT is optimized for low network traffic, while POWERLINK and SERCOS III handle heavier data loads better.

Communication Architecture: All systems support central control, but EtherCAT and SERCOS III have limitations with decentralized control. Direct cross-traffic is supported by POWERLINK and SERCOS III, enhancing real-time performance.

Data Traffic and Jitter: Systems with prioritization mechanisms achieve lower cycle times. EtherCAT, POWERLINK, and SERCOS III offer minimal jitter, crucial for control quality.

Implementation Costs: The document compares the costs associated with master implementation, noting that all protocols allow for software implementation on standard Ethernet chips. POWERLINK offers an open-source master, while others have varying levels of cost and hardware requirements.

Specifications and Procedures: The document discusses various Industrial Ethernet solutions, focusing on the hardware and software requirements for implementing bus protocols into slave devices. It highlights the use of ASICs or FPGAs for EtherCAT, SERCOS III, and PROFINET IRT, while microcontroller-based software solutions are feasible for POWERLINK, EtherNet/IP, and PROFINET RT. The document also explains the cost implications of these solutions, noting that FPGA-based solutions are attractive due to lower development costs and high performance.

Node Connection Costs: The document provides a cost analysis of node connections in different real-time Ethernet environments, excluding software stack license costs. It compares the costs of PROFINET, POWERLINK, EtherNet/IP, EtherCAT, and SERCOS III, noting that POWERLINK is the least complicated and cost-effective solution.

Operating Costs: Operating costs are primarily associated with maintenance and network administration. Technologies like EtherNet/IP with CIP Sync and PROFINET IRT are complex and may require significant network expertise. Synchronization technology is crucial for real-time communication, with POWERLINK and SERCOS III offering precise synchronization mechanisms.

Safety Functionality: The document outlines the increasing demands for safety in production environments, driven by the EU's Machinery Directive. It emphasizes the shift from hard-wired safety equipment to network-integrated safety systems, which offer flexibility, reduced component count, and simplified maintenance.

Black Channel Principle: Safety-oriented field buses use the Black Channel Principle to transmit safety and diagnostic data via existing network connections, reducing hardware requirements and improving response times. The principle allows for the transmission of failsafe and standard data over the same network lines.

CIP Safety and PROFIsafe Protocols: The document describes the CIP Safety protocol for data transmission via EtherNet/IP or DeviceNet, using a producer-consumer mechanism. It also explains the PROFIsafe protocol, which uses a Master-Slave mechanism for safety telegram transmission, employing CRC calculations for data integrity.

Overview: The document provides a detailed analysis of various safety communication protocols used in industrial networks, focusing on PROFIsafe, openSAFETY, and FSoE (Fail Safe over EtherCAT). It discusses their specifications, procedures, and performance criteria, highlighting the differences and advantages of each system.

PROFIsafe: PROFIsafe ensures the transmission of safety data using F-Parameters and I-Parameters for configuration. It requires manual address setting via DIP switches and uses a CPD-Tool for configuration. The system is certified up to SIL3 and supports safe motion control.

openSAFETY: Designed for safety data transmission over any network, openSAFETY uses a producer-consumer model and supports multicast messaging. It is open-source and technology-independent, allowing for large network configurations with up to 1023 safe nodes per domain. It is certified up to SIL3 and ready for SIL4.

FSoE (Fail Safe over EtherCAT): FSoE uses a master-slave architecture with unique Connection IDs for each slave. It requires manual address setting and uses CRC 16 for data integrity. The system is certified up to SIL3 and offers a safe parameterization channel.

Comparison and Performance: The document compares the protocols based on criteria such as certification, payload data duplication, multicast messaging, and safe motion control. openSAFETY is noted for its open-source implementation and compatibility, while PROFIsafe and FSoE require manual configuration. Performance is influenced by the underlying data transfer protocol, with cross-traffic playing a crucial role in optimizing reaction times.

Conclusion: Each protocol has its strengths and limitations, with openSAFETY offering the most flexibility and ease of integration due to its open-source nature. PROFIsafe and FSoE are more limited by their specific protocol requirements, impacting implementation and integration efforts.

Catalog excerpts

SYSTEM COMPARISON The 5 Major Technologies nd E d i t i o n 2 PROFINET, POWERLINK, EtherNet/IP, EtherCAT, SERCOS III How the Systems Work The User Organizations A Look behind the Scenes Investment Viability and Performance Everything You Need to Know! Safety protocols Learn the basics!

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Stéphane Potier Huazhen Song Bhagath Singh Karunakaran Stefan Schönegger Anton Meindl Peter Wratil Luca Lachello Outsiders are not alone in nding the world of Industrial Ethernet somewhat confusing. Experts who examine the matter are similarly puzzled by a broad and intransparent line-up of competing systems. Most manufacturers provide very little information of that rare sort that captures technical characteristics and specic functionalities of a certain standard in a way that is both comprehensive and easy to comprehend. Users will nd themselves even more out of luck if they are seeking material...

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Systems Roundup: The 5 Major Contenders nders 2nd Edition · Selection of Systems for Review · User Organizations and Licensing Regimes CRITERIA FOR INVESTMENT VIABILITY Compatibility / Downward Compatibility Electromagnetic Compatibility (EMC) · Electrical Contact Points Cabling / Feasible Topologies · Hot Plugging Capability High Availability · Gigabit Readiness Availability of Safety Solutions · Market Penetration Theoretically Achievable Cycle Time · Communication Architecture Direct Cross-Trafc · Heavy Data Trafc Network Load for Safety Communication Actual Cycle Time · Jitter · Performance...

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Selection of Systems for Review | This issue of Industrial Ethernet Facts compares PROFINET (RT, IRT), POWERLINK, EtherNet/IP, EtherCAT, and SERCOS III, i.e. ve out of about 30 Industrial Ethernet systems currently in use around the world.1 Why these ve? The selection was based on technical aspects, standardization status, and strategic market considerations. Relevant issues include e.g. whether a user organization backs the ongoing development of a protocol, whether a protocol is classied in the IEC standard, and whether a system is suitable for hard real-time requirements. Real-time A mechanism...

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Systems Roundup: The 5 Major Contenders nders 2nd Edition Market Penetration Another key aspect in selecting Industrial Ethernet systems for comparison was market penetration: various IMS and ARC surveys indicate that about three quarters of all Industrial Ethernet applications around the world use EtherNet/IP, PROFINET, or Modbus TCP. Next in line are POWERLINK and EtherCAT, two systems particularly suitable for hard real-time requirements. The following roundup does not examine Modbus TCP on its own, since its user organization ODVA has stated that it has been integrated into EtherNet/IP. SERCOS...

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Diverse Approaches to Real-time Generation There are three different approaches to building a real-time Ethernet solution: 1. Based on TCP/IP: Protocols are based on standard TCP/IP layers with real-time mechanisms embedded in the top layer. These solutions usually have a limited performance range. 2. Standard Ethernet: Protocols are implemented on top of standard Ethernet layers. These solutions benet from Ethernet evolution without further investment. 3. Modied Ethernet: The standard Ethernet layer, the Ethernet mechanism and infrastructure are modied. These solutions put performance before...

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Systems Roundup: The 5 Major Contenders nders 2nd Edition PROFINET (“Process Field Network”) is differentiated into different performance classes to address various timing requirements: PROFINET RT for soft real-time, or no real-time requirements at all, and PROFINET IRT for hard real-time performance. The technology was developed by Siemens and the member companies of the PROFIBUS user organization, PNO. The Ethernet-based successor to PROFIBUS DP, PROFINET I/O species all data transfer between I/O controllers as well as the parameterization, diagnostics, and layout of a network. Application...

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Device Profiles POWERLINK Communication Protocol Software CANopen Application Layer – Object Dictionary Messaging (SDO and PDO) POWERLINK Transport CAN based CANopen Transport Initially developed by B&R, POWERLINK was introduced in 2001. The Ethernet POWERLINK Standardization Group (EPSG), an independent user organization with a democratic charter, has taken charge of the further development of the technology since 2003. POWERLINK is a completely patent-free, vendor-independent and purely software-based communication system that delivers hard real-time performance. An open source version has...

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Systems Roundup: The 5 Major Contenders nders 2nd Edition EtherNet/IP Device Profiles CIP Application Layer Application Library CIP Data Management Services Explicit Messages, I/O Messages CIP Message Routing, Connection Management Initially released in 2000, EtherNet/IP is an open industrial standard developed by Allen-Bradley (Rockwell Automation) and the ODVA (Open DeviceNet Vendors Association). The “Ethernet Industrial Protocol” is essentially a port of the CIP application protocol (Common Industrial Protocol), which was already used by ControlNet and DeviceNet, to the Ethernet data transfer...

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Frame delay = (total byte count for header + data) x 10 ns 250 ns EtherCAT Communication EtherCAT (“Ethernet for Control Automation Technology”) was developed by Beckhoff Automation. All users of this technology automatically become members of the EtherCAT Technology Group (ETG). How It Works EtherCAT is based on the summation frame method: The EtherCAT master transmits an Ethernet frame containing data for all nodes on the network. That frame passes through all nodes in sequence. When it arrives at the last node on a trunk, the frame is turned back again. The nodes process the information in...

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Systems Roundup: The 5 Major Contenders nders 2nd Edition Non-real-time channel Real-time channel … I/O profile Motion profile Ethernet application Generic device profile A freely available real-time communication standard for digital drive interfaces, SERCOS III not only species the hardware architecture of the physical connections but also a protocol structure and an extensive range of prole denitions. For SERCOS III, effectively the third generation of the Sercos Interface that was originally introduced to the market in 1985, Standard Ethernet according to IEEE 802.3 serves as the data transfer...

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