Industrial Ethernet is an industrial-grade communication network based on IEEE 802.3 (Ethernet) technology. In response to the actual needs of low latency and massive connections in industrial application scenarios, it has made a series of necessary improvements and expansions on the basis of traditional Ethernet to meet the special requirements of real-time, reliability and security in industrial environments need.
In the field of information integration at the factory management level and workshop monitoring level, Industrial Ethernet has already had a large number of successful cases. It has also been successfully applied in situations where the equipment layer does not have strict requirements for real-time performance.
At this stage, the response time of the Ethernet communication that we often use that supports TCP/IP is usually 100ms. The real-time and deterministic issues need to be further solved before it can be widely used in industrial scenarios. Driven by some industrial equipment manufacturers, many different industrial Ethernet protocols have been produced.
EtherNet/IP
Ethernet/IP (EtherNet Industry Protocol) is a protocol system suitable for industrial environment applications. It is built on standard UDP/IP and TCP/IP protocols, using fixed Ethernet hardware and software to define an application layer protocol for configuring, accessing and controlling industrial automation equipment. It is a common industrial protocol (CIP, Control Information Protocol). ) was developed by Rockwell Automation, which mainly promotes ControlNet fieldbus, for Ethernet to enter the automation field, and is mainly managed by the ODVA Association (Open DeviceNet Vendors Association).
The EtherNet/IP protocol is an excellent industrial Ethernet solution. Because it uses the same application layer protocol and new producer/consumer communication model as DeviceNet and ControlNet, control network devices can transmit data more efficiently and integrate with the Internet/Intranet more easily.
The OSI reference model of EtherNet/IP has the same physical layer, link layer, network layer, and transport layer as standard Ethernet. The characteristic is that it adds an encapsulation layer above the transport layer to format the data from the application layer. encapsulation, and the application layer uses the CIP protocol to meet some of its functions and services in the field of industrial automation.
The Ethernet/IP network uses commercial Ethernet communication chips, physical media and star topology, and uses Ethernet switches to realize point-to-point connections between devices. It can support both 10Mbps and 100Mbps Ethernet commercial products. The Ethernet/IP protocol is adopted by IEEE 802.3
It consists of three parts: physical layer and data link layer standards, TCP/IP protocol group and control and information protocol CIP. The first two parts are standard Ethernet technology, and its characteristic is the CIP part called control and information protocol.
EtherNet/IP establishes communication from one application node to another through a TCP connection and multiple CIP connections. Multiple CIP connections can be established through a TCP connection. Since EtherNet/IP uses the physical layer network of Ethernet and structures the TCP/IP communication protocol, it can be implemented using software on a microprocessor and does not require a special ASIC or FPGA.
EtherNet/IP uses standard Ethernet and switches, so it can have an unlimited number of nodes in the system and can deploy a network across many different endpoints on the factory floor.
PROFINET
PROFINET is an open industrial Ethernet standard defined by PROFIBUS & PROFINET International (PI). It is widely used in industrial automation and process control fields through Siemens control systems. It complies with the content under the IEEE 802.3 specification and has automatic negotiation, automatic Cross-functional, it is often considered the successor of PROFIBUS. Years of experience with PROFIBUS ensure a smooth transition to the globally accepted Ethernet communication technology (PROFINET).
PROFINET applies TCP/IP and related standards of information technology. It is a real-time industrial Ethernet. Since 2003, it has been part of the IEC61158 and IEC61784 standards. PROFINET=PROFIBUS+EtherNet transplants the master-slave structure of PROFIBUS to Ethernet, so PROFINET will have Controller and Device, and their relationship can simply correspond to the Master and Slave of PROFIBUS.
It comes in three different categories: PROFINET Class A provides access to the PROFIBUS network through a proxy, bridging Ethernet and PROFIBUS with the help of remote procedure calls over TCP/IP. Its cycle time is about 100ms, mainly used for parameter data and cyclic I/O. Typical applications include infrastructure and building automation; PROFINET Class B is also called PROFINET real-time (PROFINETRT), which introduces a software-based real-time method and combines the cycle The time is reduced to about 10ms. Category B is usually used for factory automation and process automation; PROFINET Category C (PROFINETIRT) is isochronous real-time transmission and requires the use of dedicated hardware to reduce the cycle time to less than 1ms, thus making it more popular in real-time industrial Ethernet. Provides the performance required for motion control operations.
PROFINET supports star, bus and ring topologies. In order to reduce wiring costs and ensure a high degree of availability and flexibility, PROFINET provides a large number of tools to help users easily implement PROFINET installation. Specially designed industrial cables and durable connectors meet EMC and temperature requirements and are standardized within the PROFINET framework, ensuring compatibility between devices from different manufacturers.
An important feature of PROFINET is that it can transmit real-time data and standard TCP/IP data at the same time. In its common channel for transmitting TCP/IP data, various proven IT technologies can be used (such as http, HTML, SNMP, DHCP, XML, etc.). When using PROFINET, we can use these IT standard services to strengthen the management and maintenance of the entire network, which means cost savings in debugging and maintenance.
Modbus TCP
The Modbus TCP protocol is a variant of the Modbus protocol based on the TCP/IP network and was launched by Schneider Electric in 1996. It encapsulates the Modbus protocol in the TCP/IP protocol stack, uses Ethernet as the physical layer, and implements communication between devices through TCP connections.
Modbus TCP is a derivative of the simple, vendor-neutral Modbus series communication protocols used to manage and control automation equipment. Obviously, it covers the use of Modbus messages in Intranet and Internet environments using the TCP/IP protocol. The most common uses of the protocol are for I/O modules such as PLCs, and gateways connecting other simple domain buses or I/O modules.
Modbus TCP protocol supports point-to-point communication, that is, one-to-one communication. Each Modbus TCP device has a unique IP address, which allows direct communication with the specific device. Modbus TCP supports multiple data types, including integers, floating point numbers, Boolean values, etc.
At the same time, it also supports a variety of data structures, such as a single register, multiple registers, and bit registers. Regardless of the variant, all standard ModBus communications follow the same messaging structure. Everything revolves around storing values in registers and then reading them.
Modbus TCP uses TCP/IP Ethernet to transmit Modbus messages between sites. Modbus TCP combines the Ethernet physical network and network standard TCP/IP as well as the data representation method using Modbus as the application protocol standard. Modbus TCP communication messages are packaged in Ethernet TCP/IP data packets.
Based on Modbus serial communication, Modbus TCP removes the checksum (because TCP itself has a checksum) and device address (Modbus TCP weakens the device address and replaces it with an IP address), plus MBAP messages Header (7 bytes)
Modbus TCP provides an elegant solution to facilitate Modbus communication over modern network infrastructure, thereby enhancing the protocol’s relevance in today’s digitalized industrial environment.
FF-HSE
Foundation Fieldbus FF (Foundation Fieldbus) originally included two parts: low-speed bus H1 and high-speed bus H2. The transmission rates of H2 are 1Mbps and 2.5Mbps, and the transmission distances are 750m and 500m respectively. Due to the low-speed development of technology and the penetration of Internet technology into control networks, H2 has not been able to meet the needs of applications before it was officially released. It was changed to HSE (High Speed Ethernet) with a transmission rate of 100Mbps and it can support low-speed All functions of bus H1 are supplements and enhancements to H1. The HSE specification was released on March 29, 2000.
HSE is a high-speed fieldbus based on Ethernet+TCP/IP protocol and running on 100Base-T Ethernet. Its model adopts the physical layer, data link layer, network layer, transport layer and application layer in the OSI reference model, and adds a user layer to the application layer. The structure of HSE is an enhanced standard Ethernet mode. The bottom layer uses the latest technology of standard Ethernet IEEE802.3μ and CS-MA/CD link control protocol for media access control.
The TCP/IP protocol is located at the network layer and transport layer, realizing connection-oriented and connectionless data transmission, and is used for Distributed Host Control Protocol (DHCP), Simple Network Time Protocol (SNTP), Simple Network Management Protocol (SNMP) and field devices.
The access agent (FDAAgent) provides transmission services. HSE system and network management agents, function blocks, HSE management agents and field device access agents are all located in the user layer and application layer, providing device description and access.
Function blocks can directly connect to high-speed networks by adding any special equipment as needed. At the same time, it also enhances the interoperability of HSE equipment from another aspect.
In addition to high bandwidth and better openness, HSE features flexible network and device redundancy forms and flexible function block technology. HSE fully embodies the concept that fieldbus is not only a communication protocol, but also a programming language, so that system configuration, equipment maintenance and diagnosis can be realized with a unified language. The combination of HSE and H1 enables FOUNDATION fieldbus to cover a wider range of control application areas.
EtherCAT
EtherCAT, the full name of EtherNet Control Automation Technology, is a real-time Ethernet technology proposed by the German company Beckhoff. It is a high-performance industrial communication protocol for deterministic Ethernet. It extends It complies with the IEEE 802.3 Ethernet standard, enabling data transmission to have the characteristics of predictable timing and high-precision synchronization.
EtherCAT technology overcomes the system limitations of other Ethernet solutions. With this technology, there is no need to receive Ethernet data packets, first decode them and then copy the process data to the individual devices.
The EtherCAT slave device reads the corresponding addressing data when the message passes through its node. Similarly, the input data is inserted into the message as it passes. Since this process is completely processed in hardware, the message is only delayed by a few nanoseconds during the entire process, allowing extremely short response times.
EtherCAT supports almost all topologies. Therefore, bus-shaped structures originating from fieldbus can also be used for Ethernet. Combining bus and branch structures is particularly helpful in system wiring. All interfaces are located on the coupler, eliminating the need for additional switches. Of course, a traditional switch-based star Ethernet topology can also be used.
EtherCAT is a MAC layer protocol that is transparent to any higher-level Ethernet protocols such as TCP/IP, UDP, Web servers, etc. In terms of topology, EtherCAT supports almost any topology type, including all device connection topologies such as line, tree, ring and star, and is not limited to the number of cascaded switches or hubs.
In other words, EtherCAT can connect up to 65,535 nodes in the system, and the EtherCAT master station can be a standard Ethernet controller, thus simplifying network configuration. With low latency per slave node, EtherCAT provides a flexible, low-cost, and network-compatible industrial Ethernet solution. As a “young” communication protocol, it has developed particularly rapidly in recent years, and the number of nodes has increased exponentially.
POWERLINK
POWERLINK is developed by the Austrian automation company B&R Industrie-Elektronik (B&R). It is based on ordinary Ethernet but does not require professional chips. It can be implemented on various platforms (such as FPGA, ARM, etc.). It is highly Real-time, open source fieldbus solution.
POWERLINK is a real-time communication protocol on standard Ethernet, adopted on IEEE802.3, so network topology, cross-connection and hot-plugging can be freely selected.
POWERLINK is an extension of Ethernet that mixes polling and timeslicing mechanisms to provide: time-critical data can be guaranteed to be sent in a very short isochronic (Isochronic) cycle, with a planned response time; all data on the network Nodes can be time-synchronized (Time-synchronized), with an accuracy of less than microseconds; relatively non-time-critical data transmission is transmitted in a dedicated asynchronous channel.
The current implementation has a cycle time of less than 200 μs and a time accuracy (Jitter) of less than 1 μs. The POWERLINK master station or “managed node” uses packet jitter to control time synchronization to within tens of nanoseconds. Such systems are suitable for a wide range of automation systems, from PLC-to-PLC communication and visualization to motion and I/O control.
POWERLINK safety technology is the most complete safety system currently in use. It includes SafeLOGIC, Safety I/O, SafeMotion, and SafePOWERLINK as a complete safety system that meets the safety and security consistency certification standards of IEC61508 SIL3 and PL e levels.
Sercos III
Sercos III (Serial Realtime Communication System) is a hard real-time full-duplex bus that can provide communication between controllers, motion devices (such as servo drives or inverters), input devices (such as bus couplers), other devices (such as encoders or communication between other sensors) and standard Ethernet nodes provides a transmission rate of 100 Mbit/s.
Sercos is based on the Ethernet standards IEEE 802.3 and ISO/IEC 8802-3. Interface definitions, protocol specifications, and mapping of protocols to network technologies are unified in the IEC 61800-7 series.
Sercos has been popular in factory automation applications (suitable for mechanical engineering and construction) for more than 30 years. Sercos III is its third generation protocol, developed in 2003. This efficient and deterministic communication protocol integrates the real-time data exchange of Sercos interfaces with Ethernet, providing real-time Ethernet and standard TCP/IP communication to create low-latency industrial Ethernet.
Much like EtherCAT, packets are processed from Sercos III by quickly extracting the data and inserting it into Ethernet frames, resulting in low latency. SercosIII divides input data and output data into two frames. Cycle times start at 31.25 microseconds, which is as fast as EtherCAT and PROFINETIRT.
One SercosIII master device can control multiple SercosIII slave devices (such as drives, sensors, and analog and digital I/O devices). One master device can control up to 511 slave devices (ie, slave nodes). It is mainly used for servo drive control. .
New features of Sercos III include line topology (previously there was a ring topology), direct cross-communication between slaves in the same ring or line, interfaces for synchronization and communication between multiple groups of motion controls, Hardware redundancy for fault tolerance in the event of a loop interruption, hot plugging for connecting and removing running nodes, safe communication for drive-integrated safety functions, and cycle times that are half the minimum of the previous SERCOS interface (31.25 microseconds vs 62.5 microseconds)
CC-Link IE TSN
CC Link IE TSN is an Ethernet-based industrial communication standard. It builds on early CC Link IE concepts and combines them with the ideas of Time Sensitive Networking (TSN), resulting in improved communication capabilities and synchronization accuracy. These standards are maintained by the CC-Link Partner Association (CLPA).
CC-Link IE TSN incorporates TSN technology to improve the overall openness. In the CC-Link IE TSN protocol, layer 2 of the OSI reference model is based on TSN technology, consisting of layers 3-7 CC-Link IE It is composed of TSN independent protocol and standard Ethernet protocol, which enables seamless and smooth connection from high-level IT systems to OT systems at the production site, thus enabling a large number of applications to be expanded and used in production.
CC-Link IE TSN uses IEEE 802.AS for time synchronization and IEEE 802.1Qbv for scheduling management. In addition, IEEE 1588v2 can also be used for time synchronization. Implementation standard component CC-Link IE TSN (workshop) can be integrated into advanced IT networks (offices, e.g. ERP) to realize smart factories (Industry 4.0), with 1Gbit/s or 100Mbit/s bandwidth and Time Sensitive Networking (TSN) , allowing the transmission of deterministic real-time data streams and standard Ethernet data streams (Webserver, FTP, SNMP…) via the same network.
CC-Link IE TSN can achieve a minimum link scan cycle of 31.25μs, which can greatly shorten the production cycle at industrial sites and improve the production capacity of the entire factory.
Not only that, CC-Link IE TSN uses time division (IEEE802.1Qbv) to define multiple connection scan cycles in the same network, and set corresponding link scan cycles according to the characteristics of different products, such as servo systems and security equipment.
High-speed cycles can be defined, while medium-speed or low-speed cycles can be used for temperature and humidity sensors, etc., so as to achieve maximum network bandwidth utilization and increase the overall factory production capacity.
TSN
TSN is the English abbreviation of Time-Sensitive Network. It is the collective name for a series of data link layer protocol specifications developed by the IEEE 802.1 TSN working group. It aims to achieve deterministic minimum time delay in non-deterministic Ethernet networks. , which defines a time-sensitive mechanism for Ethernet data transmission, adding determinism and reliability to standard Ethernet to ensure that data is transmitted in real-time, deterministically and reliably.
In addition to real-time capabilities and determinism, TSN has another huge technical advantage, which is network scalability, which allows TSN to operate at a rate of 10Mbps, 100Mbps, 1Gbps or 10Gbps. However, this requires careful (and therefore more complex) network configuration.
Transmission rates of 1Gbps and above are the logical evolution of today’s networks. 1Gbps opens the way for new (Internet of Things) applications and helps overcome performance bottlenecks in data-intensive applications. However, TSN as a system can only be fully effective when both the terminal and the Ethernet switch support TSN functionality.
TSN is a local area network (LAN) level solution that works with non-TSN Ethernet, but timeliness is only guaranteed within a TSNLAN. Users can group TSN standards based on the use case TSN solves: common time view, guaranteed extreme latency, or coexistence with background traffic or other traffic. Like any popular standard, TSN’s standards toolbox is constantly evolving.
TSN regulates data communication in Layer 2 of the ISO/OS reference model. Strictly speaking, TSN represents Layer 2 of Ethernet that supports real-time performance, and is not a complete real-time protocol. In other words, TSN will not replace PROFINET, EtherNet/IP and similar Ethernet protocols.
Instead, these Industrial Ethernet protocols will support Layer 2 TSN in the long term, so traditional Industrial Ethernet protocols will not disappear, but will be built on top of TSN in the future. However, fieldbus may be permanently replaced by Ethernet.