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Ethernet

How Ethernet is revolutionising data transmission


Ethernet is a data transmission technology for wired networks and is the standard for transmitting data packages in local home or office networks (LAN, Local Area Network).


Within such a network, all connected electronic devices such as computers, printers and servers can communicate with one another via LAN cables.


Data is sent and received via Ethernet. Ethernet does not work wirelessly like WLAN, but rather is only wired. In networked industrial environments, wired Ethernet offers a significantly higher data transmission rate and reliable transmission stability than the alternative networking via WLAN (Wireless Local Area Network).


The American working group IEEE (Institute of Electrical and Electronics Engineers) has defined and standardised the Ethernet network protocol and the structure of its packages with the IEEE specification 802.3.

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The relevance of Ethernet


The Ethernet standard began in the 1970s. Back then, however, only a very low transmission rate was possible. Over the past few decades, data transmission technology has developed steadily so that speeds of up to 10,000 Mbit/s or 10 Gbit/s can now be achieved. This is also referred to as Gigabit Ethernet.


With the advent of Industry 4.0 and the Internet of Things, the time had come to further develop the possibilities of data transmission. This new economic environment required IT systems from building and office networks to merge with industrial machine networks. This changed the type of communication and thus the requirements for data transmission.


It quickly became clear that the properties of the classic Ethernet from building cabling were no longer sufficient for industrial environments.

What does "Ethernet" actually mean?

Ether


Ancient Greek word derived from the ether theory, meaning "heaven". In previous centuries, it was assumed that the ether was a medium through which electromagnetic waves were propagated in space.

Net

What is what: Ethernet vs industrial Ethernet


Industrial Ethernet is the successor to conventional office LAN Ethernet and is primarily used for data communication in industrial production. There are good reasons for this: it offers seamless network infrastructure in real time. The fields of application are diverse, from the field level and control level to the corporate management level (Manufacturing Execution System [MES] for order coordination and Enterprise Resource Planning [ERP] for material planning).


Industrial Ethernet technology also offers a very large address space. IPV6 addressing enables networks with a virtually unlimited number of nodes to be implemented. Large amounts of data can be transmitted simultaneously at high speeds of up to 40 Gbit/s via copper. This also applies to data communication over long distances: in comparison to copper cables, fibre optic cables can bridge distances of up to 80 km. Networks can be easily expanded and segmented using switches and routers.

Advantages of industrial Ethernet compared to Fieldbus technology


Fieldbuses are bus systems used at field level to connect sensors and actuators to exchange information with a control computer. Fieldbuses originated in production technology. They are still primarily used there.

To the functioning of Fieldbuses and the areas of application

When it comes to automation, communication processes usually take place across several levels. Industrial Ethernet is used in industrial automation wherever the functions of Fieldbuses are no longer sufficient. After all, the advantages of Industrial Ethernet are:

  • Possibility of networking across multiple levels of the automation pyramid
  • Significantly faster data transmission
  • Improved real-time properties
  • Greater technical performance
  • Transmission of larger data volumes
  • Integration of safety protocols

Connection to wireless networks possible


With wireless LAN, data is transmitted wirelessly within a network using wireless technology. Intelligent wireless solutions are also becoming increasingly popular in the industrial sector. The result is a complex, dynamically designed radio field.
It is possible to transmit data between wireless and wired networks, meaning that WLAN and Ethernet can communicate with one another.

Advantages of wireless technology:


  • Connection of mobile network participants with stationary participants
  • Connection to rotating participants such as carousels or cranes
  • Construction of wireless bridges across building boundaries or water
  • Communication with participants that are difficult to access

Disadvantages of wireless technology:


  • Radio waves are diffracted at obstacles
  • Radio waves are reflected by obstacles
  • Radio waves can be attenuated when passing through
  • Radio waves can be intercepted and exploited without authorisation

When wireless is simply not possible


The use of a wired solution still has the greatest advantages in industrial production. The cable serves as an exclusive, consistent medium with fixed transmission properties, and to clearly identify the network participants. Anyone who uses Ethernet as a data transmission technology can use copper cables or fibre optic cables to distribute data packages.

Simple network communication via Ethernet protocol standards


A protocol or network protocol is a standardised set of rules for exchanging data, i.e. a type of network language. This is used for communication between computers and devices.

Standardised protocols are also known as protocol standards.

Basic information on protocol standards

Find out more about the key protocol standards for Ethernet technology below:


PROFINET is the leading open industrial Ethernet standard in Europe for all areas of industrial automation technology. This type of communication system enables data to be exchanged in real time between controller devices and field devices using industrial Ethernet. PROFINET is the successor to PROFIBUS, a Fieldbus protocol standard which is standardised by the PROFIBUS & PROFINET International (PI) user organisation. LAPP is playing an active role in further developing PROFINET.


The RT (Real Time) variant of PROFINET enables controller devices and field devices to communicate in real time. No additional requirements need to be placed on the network components to do so. The cycle times for exchanging data without any clock synchronisation are approx. 10 milliseconds. The RT variant is used in remote I/O systems, for example.


When it comes to special applications that require clock synchronisation, e.g. synchronisation of servo drives, it is essential to use isochronous communication between the controller device and field device, as provided by the IRT (Isochronous Real Time) variant of PROFINET. IRT networks place additional requirements on the hardware, and standard Ethernet switches are no longer permitted. The cycle times for exchanging data are less than 1 millisecond.

EtherNET/IP is an industrial bus system for use in control and automation systems, and is increasingly being used in the American region.


EtherNET/IP operates using standard Ethernet hardware and uses the transport protocols TCP/IP and UDP. It also uses the application protocol CIP (Common Industrial Protocol), which constitutes the application layer in the network. One key advantage offered by this open industrial standard is that it is easy to integrate existing field devices with a serial RS interface. The communication services supply the automation application with cyclic and time-critical data from the field level.


However, since such networks are able to achieve cycle times of "only" around 10 ms, the communication standard is not, by itself, suitable for handling the demanding real-time requirements of isochronous servo operation (< 1 ms). For applications requiring clock synchronisation, the protocol was therefore expanded to include MotionSync and CIPSync.


EtherNET/IP is maintained and further developed by the Open DeviceNet Vendor Association (ODVA). LAPP is a member of the ODVA and plays an active role in further developing the EtherNET/IP system.

In Asia, CC-Link IE is the leading Ethernet-based successor standard to the CC-Link Fieldbus system. In industrial applications where CC-Link reaches its limits as a Fieldbus system, the more powerful CC-Link Industrial Ethernet variant is used to manage considerably larger volumes of data. This standard for high-speed data transmission offering Gbit-level performance supplies real-time protocols and can currently connect up to 120 devices within a network. CC-Link IE is available in versions including CC-Link IE Field (for exchanging data at field level), CC-Link IE Control (for exchanging data at controller level), CC-Link IE Safety (for linking safety controllers for secure communication) and CC-Link IE Field Motion (for synchronising servo drives).


LAPP is a member of the CLPA (CC-Link Partner Association) user organisation and plays an active role in further developing the standard. Many of the components offered below have been certified in accordance with CLPA specifications.

EtherCAT is a widely used protocol for Industrial Ethernet and guarantees high-speed Ethernet. The designation stands for Ethernet for Control Automation Technology and is considered to be particularly fast Ethernet in terms of throughput rates and real-time capability.


For communication, EtherCAT uses standard Ethernet frames, processable data packages. These data packages consist of an Ethernet header, an EtherCAT header, 1 to 15 EtherCAT datagrams and a testing mechanism for detecting bit errors.


The control is provided by a communication system with a master and one or more slaves. The master sends the TARGET conditions to the slaves, which return the ACTUAL condition. For example, it is possible to transmit control instructions and answer questions about the current state of a machine.


The master creates EtherCAT diagrams from the acquired data and sends these to the connected slaves. As previously mentioned, what makes EtherCAT special is its speed. This is achieved as follows: while the data packages are still running through the slaves, each slave only takes the TARGET conditions from the diagram that apply to it and inserts its ACTUAL condition directly. Any data not intended for the respective slave is not processed and is forwarded immediately. Even with a high number of connected slaves, the communication time is very fast as the throughput delay per slave is just a few nanoseconds.

TSN standard for effective control of real-time critical data


TSN, short for Time-Sensitive Networking, describes a way of controlling and prioritising data flows in Ethernet networks. However, Ethernet TSN is not an independent communication protocol, but rather a set of standards that define the functions of protocols. These function definitions can then be used by different protocols such as PROFINET.


The aim of developing the TSN standards is to intelligently merge information technology with industrial engineering. To do this, it requires data transmission from real-time critical applications, such as signal acquisition of a safety-relevant component.


By defining and expanding existing Ethernet standards, TSN achieves convergence between IT and the connected machines and devices. By effectively controlling real-time critical data and data-intensive applications, the Ethernet network can be implemented via a single common Ethernet cable.