What is SERCOS interface?

SERCOS interface is an open interface specification for the communication between controllers and intelligent digital drives.

SERCOS interface is the only standardized open motion control communication interface. It was approved as International standard IEC 61491 in 1995 and as European standard EN 61491 in 1998.

SERCOS interface is based on an optical ring topology with a time-triggered master-slave communication. The bandwidth is 2, 4, 8 and up to 16 MBaud with a very high protocol efficiency. The net data thoughput is comparable with that of the Fast-Ethernet (100 MBaud) communication standard.

SERCOS interface allows cycle times down to 62.5 us with a very low jitter below 1us thus allowing a deterministic real-time data communication especially required for synchronous multi-axes motion control applications.

SERCOS interface is expandable. It imposes no limit to the number of rings which can be synchronized together. The real limit is with the controller, which will have a limit to the number of axes it can process.

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Use of the SERCOS interface trademark

When using the SERCOS name or trademark in written communications the trademark should stand out through the use of capitalization as shown below:

SERCOS Technology is ...
SERCOS products can efficiently ...
SERCOS devices provide ...


The first time the trademark is used in textual information the supplement "interface" and the Registered Trademark ® symbol should be added in subscript format.

SERCOS interface®


The trademark should be kept separate from other words, symbols or numbers. Do not use hyphens or connect SERCOS with other words: say "Products with SERCOS Technology", rather than "SERCOS-enabled products".

The use of the SERCOS trademark is regularized in the trademark statutes of the SERCOS International e.V.

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Who can use SERCOS?

There are thousands of digital control systems communicating via SERCOS around the world. It is estimated that the majority of SERCOS axes in the field today are on non-machine tool applications. Especially applications with many axes that need to be strictly synchronized benefit from the outstanding performance of the SERCOS technology.

Some examples of application:

Web-fed printing presses; packaging, converting & food processing machines; assembly, handling and robots; semiconductor processing equipment; metalforming and welding machines; textile processing; fiber winding; simulators and test equipment; plastics machines and many other types of special machines.

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SERCOS development -- History

SERCOS was created by a group of drive, control and machine tool manufacturers in 1986 at the request of a machine tool builders' organization, whose members desired an open communication system. The consortium's main aims were:

-- cost-effectiveness
-- "plug&play" interface
-- independence of control and drive technology
-- interoperability
-- cross-vendor comatibility

This activity led to the first release of the SERCOS specification in 1989.

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Who maintains the SERCOS standard?

The SERCOS Technical Working Groups (TWG) in N.A. and Europe hold meetings 5 to 6 times per year.

Some of their duties are:

-- Specify new functions and ident numbers
-- Extend and improve existing functions
-- Publish Technical Updates
-- Support manufacturers and users of SERCOS products
-- Define compatibility classes and function groups
-- Prepare all information necessary to update the standard

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SERCOS in comparison with other servo communication buses

Advantages of SERCOS:

SERCOS products must pass a conformance test to ensure that they are compliant to the standard. Thousands of multi-vendor installations prove the cross-vendor compatibility of the SERCOS standard.

Updates to the SERCOS standard are defined by multi-company Technical Working Groups (TWGs) in both North America and Europe, which ensure that the latest enhancements proposed by SERCOS member companies are incorporated into the specifications.

SERCOS defines not only the physical layer and the communication protocol but furthermore the semantics of motion control functions by over 400 standardized parameters (so-called IDNs = IDentifier Numbers).

Fibre Optics provide high operating speed and good noise immunity.

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Where can I get technical help?

Contact any of the SERCOS member companies or qualified systems integrators for product-specific information and applications assistance.

Contact a SERCOS Competency Center for fee-based services, including training, application support and hot-line telephone support.

To request a copy of the SERCOS interface standard (IEC 61491) please contact the respective publishers.

For the actual versions of the SERCOS interface specification (working document) and the application notes (available in German and English) please contact the SERCOS International office.

For general technical questions please contact the technical hotline of SERCOS International by email.

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