All About SERCOS

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SERCOS North America
Motion Engineering, Inc
SGS Thompson
Hewlett Packard
Pacific Scientific
Sanyo Denki

About The SERCOS Interface

Frequently Asked Questions (FAQ) by SERCOS N.A.

SERCOS stands for SErial Real-time COmmunications System

It is an open controller-to-intelligent digital drive interface specification, designed for high speed serial communication of standardized closed-loop data in real-time over a noise-immune, fiber-optic cable.

SERCOS takes full advantage of today's intelligent digital drive capabilities by not only replacing the de-facto +10 Volt analog interface standard, but also by allowing powerful two way communications between control and drive.

Intelligent motion control has come of age. Just as industrial controllers now do much more than merely replace relays, programmable motor-drives are now recognized to be the heart of flexible automation.

The recent development of intelligent digital drive technology has set the stage for a real breakthrough in motion control technology. It offers the industrial automation world the same type of quantum leap that distributed computing has offered the office automation world. Although SERCOS is vastly different from a sensor fieldbus in functionality, a digital communications protocol for motion promises the same dramatic improvement in factory floor communications integrity.

The sum of these trends is the SERCOS interface (IEC 1491). Simply put, SERCOS is the only internationally approved, digital open standard with the performance required to synchronize multi-axis motion control.

Oview of SERCOS

SERCOS stands for SErial Real-time COmmunications System. It's an open controller-to-intelligent digital drive interface specification (IEC 1491) designed for high-speed serial communication of standardized closed-loop data in real time over a noise immune, fiber-optic cable.

SERCOS was created in 1986 by a consortium of machine-tool, industrial-drive, and numerical-control manufacturers that were looking for an open (nonproprietary) communications system that would take advantage of the features predicted for intelligent drive technology. For example, multiaxis motion control in a distributed architecture requires a bus protocol that supports high-speed synchronous transmission of digital data to perform electronic gearing, cam profiling, registration control, and interpolation functions; functions for which SERCOS was specifically designed.

The concept of synchronization not only applies to the bus, but the cyclic operations that occur within the control and the drive. If synchronization is not preserved, a "beat frequency" develops, which could adversely affect the end product. The communication between these three elements is handled by a fiber-optic cable, which not only handles the synchronization of all elements connected, but saves the user cost by reducing the number of electrical terminations.

SERCOS became a European Preliminary Standard in 1991, and in 1995 was approved by the IEC. It is now published as IEC 1491, an international standard. All control or drive manu-facturers wishing to put their products on the SERCOS ring have access to the specification, either through the IEC or the American National Standards Institution (ANSI, New York), by requesting IEC 1491, "system Interface."

Commication Requirements for High-Performance Motion Control Systems

mast-slave commication (1 master, several slaves)

cyclic transmission of process data

optional noncyclic transmission of diagnostic data

synchronization of processing in all peripherals (e. g. drives, I/Os)

transmission cycle in the order of 0.5 ms to 5 ms

noise immunity and isolation of all stations to avoid mutual interference


SERCOS Promotion and Standards

  • IEC - International Electrotechnical Commission in Switzerland (IEC 1491)

  • Interests Group SERCOS interface

  • SERCOS North America - at the Centre for Systems and Control, Glasgow University, UK
    SERCOS (IEC 61491) Developer's Kit

  • ANSI - American National Standards Institute (IEC 1491)

  • Indramat IEC 1491: Technical Short Description from Indramat


  • Kollmorgen

  • Indramat

  • SERCOS Motion Controllers from Motion Engineering, Inc
    Motion Developer's Kit:
  • DSP Series Motion Control: [Installation Manual] [C-Programming Manual]
  • Sample Application Reference Guide
  • PC-Based SERCOS Interface Design

  • IAM - Development Tools for SERCOS

  • SGS Thompson - You can search for general information on the SERCON410B by its ordering number - SERGBQA or read this 30-page Datasheet (updated August 1994) of SERCON410B in PDF format.

  • SERCON816: Datasheet

  • Hewlett Packard - This link takes you to their homepage.

  • Hewlett Packard: HFBR-0600 Series - SERCOS Fiber Optic Transmitters and Receiver.

  • AMP - Fiber-optic cable/connector manufacturer. A no-charge registration is required to view contents of the site.

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