Industrial Ethernet Protocols

Overview

What is Ethernet?

Ethernet is a widespread communication standard for quickly transferring large amounts of data between devices. Without Ethernet, it would be impossible to communicate in today’s world as most networked devices use the Ethernet standard.

Data are transferred via Ethernet, as is the case with other kinds of interface technology, in the form of electrical voltage variations or light signals over fiber optics, or over radio waves via Wi-Fi.

Ethernet is extremely flexible and can be used in a multitude of environments, from home through to large corporate networks. And whilst field bus systems once reigned supreme in factory automation, the tables have now turned in favor of Ethernet.

It was standardized in IEEE 802.3 back in 1983 and covers layers one and two of the seven layers in the OSI model. Simply put: layer one, the physical layer, ensures that the bits and bytes get from A to B. Network and fiber optic cables and network interface controllers belong to this layer. Layer two, the data link, guarantees that blocks are reliably and properly transferred between two devices connected via layer one. Switches and MAC addresses belong to this layer, for example. Everything else, such as the protocols used, is located in the upper layers three to seven of the OSI model and is not specified in the IEEE 802.3 for Ethernet.

_9AP0465_a3

What is Industrial Ethernet?

Ethernet and Industrial Ethernet are essentially the same thing, the difference being that robuster components that meet industry requirements are used for Industrial Ethernet. These components must be able to withstand extreme temperatures, humidity, vibrations and electromagnetic disturbances, for example. Their fundamental physical ways of working, however, remain the same. This means that Industrial Ethernet components can also be used in “normal” Ethernet networks.

A straightforward example to illustrate the difference between Ethernet and Industrial Ethernet components is the connector. A RJ45 connector is usually used for Ethernet. This works well at home or in the office, but is unsuitable for the harsh industrial environment. As such, a D-coded M12 connector is used for Industrial Ethernet. This has a protection class of up to IP69K, as well as significantly higher mechanical strength.

 

_9AP1779_a2

Why does a device need an Industrial Ethernet interface?

When a device produces data which is then to be forwarded, an interface is required for data transmission. Nowadays, devices that produce large amounts of data or require high speeds for data transmission use Ethernet as an interface.
IO-Link has become established on the market as another interface for smaller or more cost-sensitive devices. If only simple information needs to be exchanged, a digital IO or analog interface can also be used.

IndustrialEthernet_Infografik

What is an Industrial Ethernet protocol?

What particular requirements does industry place on Ethernet communication?

In contrast to when data are exchanged as part of the daily office routine, where it is sometimes the case that very large amounts of data are sent and received, but a lost packet or delay in sending/receiving data can be put up with (e.g. if there’s a brief delay in an email arriving or a website has to be reloaded), this cannot be tolerated in an industrial production environment. In this case, if transmission of the conditions detected or measurement data collected is unreliable or takes place too late, the machine’s current conditions/measurement value will no longer correspond to the conditions detected/measurement data collected, and the control process would take place with outdated data.

What is the solution for industrial production environments?

In order for it to be at all possible to use Ethernet in an industrial environment, we need deterministic communication. This is impossible with the TCP/IP protocol that is typically used as networks may experience unforeseeable time variations when transmitting data as a result of delays, jitters, bandwidth competition and lost packets. Specific Industrial Ethernet protocols have been developed to solve this problem, featuring short lag times, cyclic communication and deterministic reactions.

What is determinism?

In the Ethernet network, determinism refers to the predictability and consistency of data transmission times and conditions, which means that data packets are sent/received at foreseeable intervals and their delivery is always guaranteed.

 

What are Industrial Ethernet protocols used for?

Industrial Ethernet protocols like PROFINET, EtherNet/IP and EtherCAT use the same Ethernet physical layer (layer 1 & 2) as the TCP/IP protocol, for example, but fundamentally differ in some aspects when it comes to upper layers 3-7.

They offer cyclic and acyclic communication, real-time capabilities, data traffic prioritization and robustness, so the demands of factories and automation systems can be met. A data frame’s composition and significance are also precisely defined in the protocol and whilst conventional TCP/IP connections are geared towards general network requirements and use asynchronous, irregular data transmission, Industrial Ethernet protocols provide a standardized structure for data transmission, whereby data composition is precisely specified in a data packet. This provides users with easy access to various types of data, such as data on parameters, diagnosis and in/output, without them having to deal with the complicated way data packets are made up or elaborate monitoring mechanisms. Without this specification, users in automated systems would have to manually perform these processes at bit and byte level for each device individually, which would be time-consuming as well as susceptible to errors.

 

Although all Industrial Ethernet protocols are based on Ethernet, they are not compatible with each other. It is therefore impossible to operate a PROFINET device in an EtherCAT network, for example.

AKLGebhardt

A summary 

  • Ethernet is not a protocol, it is a standard of infrastructure according to IEEE 802.3 which protocols work on.
  • An Industrial Ethernet protocol is a “language” transported over Ethernet.
  • Ethernet-based protocols are not compatible with each other.

What is a gateway?

A gateway is used as an external “translator” to make it possible for devices which use different protocols or communication standards to communicate with each other.

With the MA 200 product series, Leuze provides a gateway from RS 232 to all established Industrial Ethernet protocols (PROFINET, EtherNet/IP, EtherCAT), Ethernet TCP/IP, and fieldbuses (PROFIBUS DP, DeviceNet, CANopen).

Industrial Ethernet Protocols

PROFINET

PROFINET is one of the most used Industrial Ethernet protocols in the world. Siemens control systems use the Industrial Ethernet protocol PROFINET. All sensors with an Industrial Ethernet protocol from Leuze already have this interface for integrated connectivity integrated into the device and can be recognized by the x48i designation. No additional gateway is required here.

Overview: sensors with integrated PROFINET interface

Measuring sensors


 

Identification & industrial image processing


 

Optical data transmission, network & connection technology

EtherNet/IP

Control systems from Allen Bradley / Rockwell and Schneider Electric, among others, use the Industrial Ethernet protocol EtherNet/IP. Many of Leuze’s sensors already have this interface for integrated connectivity integrated into the device and can be recognized by the x58i designation. No additional gateway is required here.

Overview: sensors with integrated EtherNet/IP interface

Measuring sensors


 

Identification & industrial image processing


 

Optical data transmission, network & connection technology

EtherCAT

EtherCAT is currently the fastest growing Industrial Ethernet protocol. EtherCAT is most notably used by Beckhoff, as well as by numerous other control system manufacturers. Many of Leuze’s sensors already have this interface for integrated connectivity integrated into the device and can be recognized by the x38i designation. No additional gateway is required here

Overview: sensors with integrated EtherCAT interface

Measuring sensors


 

Identification & industrial image processing


 

Optical data transmission, network & connection technology