Sercos III

• What is Sercos?

Sercos has been one of the leading bus systems for industrial applications for more than 25 years. It is an IEC-standardized open digital interface for high speed real-time communications between industrial controls, motion devices, I/O, other peripheral devices and standard Ethernet nodes.

This real-time technology with its millionfold proven quality, universal application possibilities and high security of investments make the Sercos automation bus the first choice in mechanical engineering and construction.

• An efficient and deterministic communication protocol based on an optical transmission system for high noise immunity is the foundation for Sercos’ success.

Today Sercos is used successfully in the most varied market sectors and applications. Sercos has established itself as the de facto standard for challenging applications that place great demands on dynamics and precision. However, Sercos not only specifies a real-time-enabled communication system, but goes a lot further and specifies over 700 standardized parameters which describe the interaction between control systems, drives and other peripheral devices using universal semantics. This creates a basis upon which devices from different manufacturers can be combined without any problems. Today, over 4 million real-time nodes are being used on a daily basis in over 500,000 applications.

• Sercos III – universal communication for automation solutions

Industrial automation requires real-time-enabled and manufacturer-independent communication solutions. Different kinds of automation devices must be able to be easily and universally connected. The open, IEC standard universal bus for Ethernet-based real-time communication, Sercos III, meets these demands today with a wide variety of benefits.

• Ethernet technology provides a tangible range of benefits:

• recognized and future-proof technology
• many times higher data throughput than field buses
• no proprietary hardware required
• use readily available standard components such as double shielded CAT5e copper cables, connectors and controllers
• universal IT concepts with an integrated transmission medium and transmission protocol from the office to the field level
• flexible and compatible automation systems because of international standards
• can connect to global networks for diagnostics and maintenance

Ethernet technology combines peripheral, driver, safety and office communication in one common medium – simple, economical and efficient.

• Sercos operating principles

• Cross communication
Sercos allows for decentralized intelligence and an unlimited capacity to work in real-time because direct communication between all devices is possible. Indirect communication between slaves by bypassing the master would compromise synchronous movements, e.g. by corrupting gantry axes or slowing down reaction times, suchy as when transmitting a trigger signal quickly. Sercos slaves can communicate via cross communication directly and with a minimum of communication dead times – this ensures unlimited real-time communication and intelligent automation structures. Control systems use the same principle to directly communicate with each other.

How it works: Given that real-time telegrams are always processed in two directions independent of the kind of topology, a direct exchange of data between any given slaves is enabled within one communication cycle (see image). This has the advantage that data can always be transmitted between the slaves within an individual communication cycle while causing minimal delay, even with increased cycle times. Moreover, all real-time data is available synchronized – that is, in relation to the general communication cycle – at every point in the network. As a result, data can be processed extremely easily, efficiently and flexibly at individual network nodes. Network diagnosis and monitoring can also be carried out as a result.