Ethernet in mechanical engineering - Part 2

Nowadays, factories are no longer production halls full of smoke and furnaces, but highly complex installations. Central control is required for coordination of machines and employees in order to obtain the highest possible efficiency and flexibility. Technical developments making this possible have happened in recent years. Machines are networked by software and thus provide feedback concerning their productivity.

Software Approaches

Three general software types are required to network an entire company. SCM (Supply Chain Management) focuses on purchasing and warehouse management, ERP (Enterprise Resource Planning) concentrates on enterprise management, and MES (Manufacturing Execution System) assists in the project management and monitoring of project control systems. The decisive factor for company is networking these three software solutions together in such a way that all sectors of the company can communicate with each other easily, comfortably, and preferably without problems. Ethernet in mechanical engineering only becomes efficient when it permits complete networking, namely not only between computers, but also between actuators, sensors, and computers.
To realize this, the International Electrotechnical Commission (IEC) tries to introduce a uniform standard for Ethernet in mechanical engineering, but this is still in the future.

Networking of Office and Machine Networks - the Ethernet

The importance of Ethernet in mechanical engineering can be seen simply from the fact that switching to this system was the most common change made by machine builders in 2009. 39 % of the respondents intend to make changes in the field of internal communication and to change soon to Ethernet. Between 2005 and 2008, the number of machines equipped with Ethernet increased from 8 % to 30 %, which shows the significant rise of the technology. Furthermore, a tendency towards TCP/IP and away from real-time Ethernet has become evident during the last three years.
In the following years, the trend towards Ethernet in mechanical engineering has become stronger. In 2010, approximately every second machine was equipped with Ethernet and 29 % with TCP/IP technology. Real-time Ethernet in mechanical engineering was used by 21 % of the users, but showed growth rates of approximately 40 %.
Even in 2012, 26 % of the investigated machine builders still intended to change the fieldbuses on their machines. This means that the market for Ethernet technology can continue to grow, especially because the technologies are being improved still further. With increasingly complex production, the technology must always offer solutions to meet the requirements.

TCP/IP vs.Real-time Ethernet

The reasons for increased use of TCP/IP are the weaknesses of real-time Ethernet in mechanical engineering. This does not facilitate project planning to the desired extent. Furthermore, several fieldbuses must be used with this technology, which would increase the operating expenses unnecessarily.
The big advantage with a TCP/IP network is the fact that large data quantities can be sent to any address in the network, but even networks should be standardized. Accordingly, the IEC also demands standardization here, so that all available network solutions are suited to the conditions in installations. Although coal furnaces have disappeared from manufacturing facilities, these installations will never be sterile. In 2007, the SERCOS III solution became a part of the IEC standards and since then offers predictable network solutions for Ethernet in mechanical engineering.

SERCOS III

SERCOS III (Serial Communication System) is an international standard for Ethernet in mechanical engineering. For more than 20 years it has offered solutions for networking of production centers, drives, and controls. In the third generation, SERCOS supports Ethernet in mechanical engineering and thus marks a milestone. It offers a data speed of 100 Mbps and, in further developed variants, use of CAT5 copper cables. Rapid communication is also assured by the fact that the master can always communicate with all slaves in the network and that additionally direct communication between different participants in the network is possible without an intermediate step at the master (so-called cross communication). This reduces the data volume and accelerates communication enormously. Further advantages of SERCOS III are the efficient ring structure of the network, low wiring expenses, and thus cost savings, as well as numerous safety functions guaranteeing trouble-free operation. Furthermore, optimization of the network does not require hubs or switches, which in most cases are expensive. Nowadays, more than 80 companies offer SERCOS III solutions and develop them further.

Another advantage of the SERCOS III solution for Ethernet in mechanical engineering is the connection of real-time Ethernet to non-real-time information. Because of this, any Ethernet-capable computer can communicate at any time with the network and can be connected to it. The use of both systems enables communication of various devices in a network. Accordingly, computers do not have to communicate in real-time, as this is not always possible.

Ethernet in mechanical engineering is still a very new technology, which however is already being used in most companies. It is being continuously developed and seems to be the standard for communication in companies, until a new, more efficient standard is established.