Industrial Ethernet

INDUSTRIAL ETHERNET

What is Ethernet/Industrial Ethernet?

Ethernet is a procedure describing hardware and software for fixed-wire data networks. Ethernet was initially intended for local data networks and thus is also called LAN technology. Ethernet thus enables the exchange of data between all devices connected to a local network in the form of so-called data packets.

Industrial Ethernet is a further development of Ethernet. Here, the object is the application of the Ethernet abilities to devices used in industrial manufacture and control (also called real-time Ethernet). Generally, the devices for control and checking of production processes are integrated into the LAN network of the employee computers which mostly already exist.

Industrial Ethernet – History

The intensive research started more than 10 years ago under the leadership of the IAONA (Industrial Automation Open Networking Alliance). The idea was the use of Ethernet in connection with TCP/IP protocols in order, to create a uniform real-time protocol based on this that can be used for the communication of automation processes. The original Ethernet with a transfer of 10 Mbps was not suitable for this communication, as it was rather collision-prone. This initially led to the development of Fast Ethernet. Here, messages were transferred without collisions by use of switches, message prioritization, and full-duplex transmission. The speed for doing this is 100 Mbps. With this, the ground for the desired fast real-time transfer had been prepared

The Basics

There are approximately 20 different protocols for Industrial Ethernet, which are oriented on IEEE 802.3. With this, fieldbus protocols are transferred via Ethernet by tunneling or encapsulation.

The advantages are the consistency of the communication systems and direct takeover of the application layer of the fieldbus and easy portability.

The disadvantage is the large overheads for using the TCP protocol.

Industrial Ethernet uses the international wiring standards.

The decisive protocol for industrial applications is the CIP protocol. This enables cyclic and time-critical data traffic of the automation technology. CIP networks are interoperable with each other. For example, this enables a DeviceNet to operate with an EtherNet/IP

Real-time Data Transfer

Industrial communication networks are divided into three communication levels:

  1. The routing level: This is found, for example, in automotive manufacturing or in process technology, i.e. in large, highly standardized and automated production installations. Here, the transfer between the individual systems in most cases is not very time-critical. Standard Ethernet (in combination with protocols of information technology) has been used here already for years.
  2. The control level
  3. The actuator/sensor level: with these two levels, the real-time characteristics of the Industrial Ethernet are of special importance.

Aim of the Industrial Ethernet

Industrial Ethernet shall establish a basis-oriented and uniform communication system between the systems of the routing level, the control level, and the sensor level, which enables communication in real-time. In this way, losses from system and transfer errors can be avoided. With this, it is especially important to define an infrastructure valid for all three levels.

Uniform Standard?

Many protocol standards competing with each other have been developed for Industrial Ethernet in the same way as for fieldbuses. Most of these standards based themselves on the fieldbus standards forming the base. However, a common core has formed with Fast Ethernet, which nowadays is being used across the board with all systems.

The developments to real-time Ethernet are supported in the European area (e.g.: EtherCAT, TTEthernet, Ethernet Powerlink, Profinet, and Sercos III) as well as in the USA (e.g.: Open DeviceNet Vendor Association (ODVA), ControlNet International (CI), and the Industrial Ethernet Association (IEA)).

Although Industrial Ethernet shows high application rates, the use of fieldbuses is still prevalent. Fieldbuses are suited especially to production processes where cyclic I/O data transfer is important (for example in machine building), while Industrial Ethernet is being used more and more, especially in production processes where performance and clock synchronicity matter.

Advantages over Fieldbuses

  • The transfer of IT data and real-time data takes place at the same time
  • Large network expansions by cascading of switches are possible
  • Transfer of larger data quantities
  • All network participants can access buses at the same time
  • The number of participants is nearly unlimited because of the large address range
  • Different transfer media can be combined (for example cable, radio, light conductors)

Problems

Wiring is consistently based on international wiring standards like ISO/IEC 11801. This forms the wiring structure for all factory and hall networks. The problem is the plug connectors: Initially, Ethernet was developed for non-industrial applications, where RJ45 jacks are mainly used.

However, hitherto unknown interference factors may occur outside the office environment, which may influence the transfer quality and can cause faults in the system. These include:

  • Vibrationen
  • Dirt
  • Humidity
  • Harmful substances

A remedy is offered by the development of new plug connections, for example the RJ45 jack with protection type classification IP67 or the M-jack. This enables, for example, use in heavy industry and in highly sterile rooms.

Industrial Ethernet – Outlook

Research makes steady advances: At present, the focus is on areas such as performance and clock synchronicity. The integration of safety protocols is also being researched extensively. The subject of energy management is also very current.

What exactly is Industrial Ethernet?

Until today, most people do not really know what Ethernet means. This term frequently occurs in connection with so-called “smart homes”. Ethernet is the network that all actuators in the smart home use to communicate with each other. If you consider the smart home – the “thinking house” – as the body, the Ethernet would correspond to the nerves and blood vessels through which the information is transferred from the brain to the individual body parts – the actuators. In the following, it will be explained why this metaphor is not 100 % correct.

Industrial Ethernet represents an adaptation of Ethernet technology to production processes. It accelerates the communication and synchronization of the actuators participating in the process.
This leads on to the question:

How does Industrial Ethernet function?

Ethernet is based on the master-slave principle: The actors of the module controlling the processes are the slaves. These are connected via a collective line to a master, which also represents a kind of central control of a group of slaves. And here comes the point why the “brain metaphor” (see above) is not 100 % correct: If it increases the efficiency of the system, the individual slaves can also communicate with each other. That would be as if the little finger of the right hand could send a message to the little toe without taking the detour via the brain. This serves to reduce the load of the central control, which can then reduce the energy consumption

What can Industrial Ethernet do

Production and manufacturing processes become increasingly complex and multi-layered. The demands for the control of these process increase correspondingly. Fieldbus systems that were in the high-tech sector only 20 years ago have not been able to compete there for some time. Here, one of the characteristics of Ethernet and especially Industrial Ethernet comes into play: The so-called real-time Ethernet, also called Fast Ethernet, transfers data with 100 Mbps. A vertical system structure further enables communication between several system components without the risk of data collision. The cycle times of the synchronization of the system are in the microsecond range.

Furthermore, the individual modules of the Industrial Ethernet network can be reprogrammed relatively quickly, which enables a new combination of the network components according to the building block concept. Such a high flexibility can scarcely be found in an industrial communications system.

What are the advantages of Industrial Ethernet?

Because of the ever accelerating globalization, more and more companies are engaged in optimization and efficiency increase of their operation. This means that they want to improve the ratio of production costs and production efforts.
Commercial users can expect the following benefits:

  • Savings through less waste because of more precise control of production processes. Dosaging processes in particular can become considerably more efficient.
  • The high flexibility of Ethernet systems creates the ability to plan for the short-term and medium-term compared to the conventional planning times. The resulting improvement of the capacity to manufacture to order reduces stock.
  • In connection with this, the downtimes of the operation installations can also be reduced.

However, the customer also has an advantage from Industrial Ethernet:

  • The ability to continuously monitor measuring values and tolerances can improve the quality of products overall.

The Installation:

The installation of different Ethernet systems is done uniformly. The field components of all Ethernet vendors are compatible with each other. The user can check this by means of a certificate intended for this purpose. Once installed, an Ethernet system also offers redundant routes of transmission in case of failure of a data line, so that the operation is impaired not at all or only slightly. Further advantages with installation and maintenance of Industrial Ethernet are:

  • Considerable reduction of the installation efforts, as only a single cable is laid.
  • With the corresponding programming, the information collected in the entire system can be accessed from any location.
  • Troubleshooting is facilitated considerably in comparison with other, older systems and the time is shortened.
  • The training of installation as well as maintenance personnel requires less time and fewer efforts.
  • Uniform confederation tools, for example the so-called sniffers, exist for maintenance, checking, and repair of all Ethernet systems.

Long-term costs

In order to keep the long-term costs for the users as low as possible, the large Ethernet vendors some years ago started an initiative for the creation of uniform maintenance tools. An international certificate guarantees the compatibility of the various field components.
The three most widely used concrete methods for maintenance are:

  1. Field Device Control (FDC)
  2. Tool Calling interface (TCI)
  3. Electronic Device Description Language (EDDL)

Why Industrial Ethernet is being used by more and more users:

The trend towards building automation is very clear. Why is Industrial Ethernet being used with this? It just has advantages over other systems. And not only that. When required, transparent transitions between Ethernet and fieldbus systems are no problem at all. Special Ethernet adapters exist for this. The trend towards building automation is caused by the fact that all private – and often also government – enterprises are under increasing efficiency pressure because of the ever accelerating globalization processes. And as they all operate profit-oriented, they all have the same goal: They want to produce a product which is as good as possible with the least possible costs and, in regard to this, in the shortest time. The question should rather be why Industrial Ethernet should not be used.

Why Industrial Ethernet can lower the costs

Commercial users have the following opportunities for saving of resources through the use of Industrial Ethernet:

  • Primary energy: Ethernet is an intelligent technology that can considerably unburden the central control of plants with corresponding programming.
  • Raw materials: Here, Ethernet can make sure that the dosaging processes within the production can be adjusted to become considerably more sensitive than before, which leads to less waste.
  • CO² certificates: In the scope of the new environment policy, Ethernet in machine engineering consequently can also lead to a lower CO² emission because of the savings in primary energy. As a result, Ethernet not only contributes to environment protection, but makes it possible for plants to spend less money for purchasing of CO² certificates.

Furthermore, plants can expect the following from the use of Ethernet:

  • Improved capabilities for monitoring of tolerances and measuring values can lead to a general quality improvement.
  • Short-term planning abilities permit a reduction of stocks because of short-term acceptance of orders. In connection with this, longer downtimes can also be avoided.

Why Industrial Ethernet is an intelligent system

The actuators of the production process are connected to the modules of the Ethernet system from which they receive their commands. These modules can be connected to a central control via collective lines. The modules are called slaves and the central controls are called masters. Accordingly, the master-slave principle is often mentioned when talking about Ethernet. The following is the reason why Industrial Ethernet is more intelligent than other systems:

The masters can communicate with each other via a network. This is just like in the human body, where all nerve stimulations are processed in the brain. However, there is one more fact in the case of the Ethernet: If it increases the efficiency, the individual slaves can also exchange data with each other. That is as if the nose, when it is itchy, could send a command to scratch to the hand without having to take a detour via the brain. This sharply reduces the load for the central control of an installation.

However, Industrial Ethernet not only thinks more efficiently than other industrial communication system, which is another reason why Industrial Ethernet enjoys growing popularity, for example in machine building. It also thinks faster: The vertical construction of the system structure enables multiple modules to transfer and to process data at the same time. The real-time Ethernet technology, also called Fast Ethernet, enables transfer rates of up to 100 Mbps – naturally without the risk of data collision. Furthermore, several signal routes are available, so that a spare connection can be used in the case of the failure of one connection.

Why Industrial Ethernet is a less expensive system

Industrial Ethernet can be installed and maintained very easily. The advantages are:

  • Troubleshooting is less complicated than with other communication systems and can be done faster. When required, it can even be done during ongoing operation.
  • Only one cable must be laid for the base installation
  • The costs for the training of maintenance and installation personnel are relatively low.
  • There are uniform configuration tools, certified and approved as operating resources, which are compatible with the systems and field components of all manufacturers.

If the programming of the system provides for it, all information collected in the system can be made available to all parts of the system and can be processed if required/possible.

Why Industrial Ethernet can be maintained easily:

Why can Industrial Ethernet be maintained easier than other systems? The reason for this can be found in the actions of major Ethernet vendors, who, because of the needs of their users, look for simple and if possible standard maintenance in the highly complex systems. Accordingly, the vendors have developed three procedures that can be used for all field components of all Ethernet systems (and the systems themselves). Their names are:

  • TCI (Tool Calling Interface)
  • FDC (Field Device Control)
  • ECCL (Electronic Device Description Language)

For the future, the vendors want to work towards use of a single technology. The name of this is: FDI (Field Device Integration).