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Introduction to Sercos interface
Applications Types
Sercos III
General Architecture
Sercos III Profiles
Blended Infrastructure
Additional Resources
Sercos I and II
Sercos Standardization
  Introduction to Sercos III
Summary of Sercos III Advantages
  Key Advantage: Communications Efficiency
  Key Advantage: Multi-axis Distributed Control
  Key Advantage: Cross Communications Capabilities
  Key Advantage: Enhanced Reliability
Key Advantage: Investment Protection

Advantages of Sercos III


  • All automation devices, i.e., controllers, servo drives, pneumatic and hydraulic controls/drives, I/O, vision systems, encoders and distributed peripheral devices, communicate via a uniform Ethernet-based network.
  • Safe and non-safe participants can coexist in one network without influencing the security technology.
  • EtherNet/IP and other Ethernet-based protocols can be transmitted at the same time as real-time data without influencing the real-time characteristics.

Fast and Direct

  • High speed: Sercos III uses 100 Mbit/sec Full-Duplex Fast Ethernet.
  • Short runtimes: runtimes through the network are reduced to a minimum. This is achieved by:

    • Extremely fast processing of the Sercos III real-time messages when passing through the devices ("on-the-fly").
    • No additional network components, e.g., hubs or switches.
  • Direct cross communication: all nodes can exchange data directly within one communication cycle.


  • Efficient usage of bandwidth: ideal utilization of bandwidth possible via multiplexing techniques.
  • Configurable cycle time: the communication cycle can be varied between 31.25 μs and 65 ms.


  • Synchronicity and simultaneity down to a fraction of a microsecond.


  • All office communication protocols (e.g., TCP/IP, UDP/IP) can be transmitted parallel to Sercos III real-time communication via the same cable. Synchronization and redundancy are not mutually exclusive.
  • Standard Ethernet protocols use MAC or IP addresses to communicate with individual Sercos III devices. Tunneling of these protocols is not necessary.
  • Commissioning and diagnosis of Sercos III devices using standardized interfaces (SCI, S/IP, and FDT/DTM).


  • Safety functions up to SIL3 according to IEC 61508 can be implemented with CIP Safety on Sercos.
  • The routing capability of CIP Safety supports safe device communication across network boundaries.
  • A safety network can stretch across diverse CIP Safety networks, for example, Ethernet/IP, DeviceNet and Sercos III.

High Availability

  • For high-availability automation solutions, Sercos III automatically offers fail-safe communication in the case of a cable break or node failure through the use of a ring topology (ring redundancy).
  • The time needed to detect and respond to a cable break is a maximum of 25 μs, so at most only the data from one cycle is lost and communication is continued thereafter.
  • If a redundancy situation occurs, the synchronization quality is maintained.


  • Centralized and decentralized control architectures are supported.
  • User-defined device configuration within the network.
  • Support of ring or line topologies. In addition, hierarchical, synchronized and real-time coupled network structures can be implemented.
  • Hot-plugging is supported without interference with real-time or synchronization functions.

Easy to Implement

  • Sercos III devices can be easily configured and commissioned via a uniform, integrated device model and universal, standardized device profiles.
  • The protocol automatically detects the device and where it is connected in the topology. This makes it easy to localize the affected device for servicing.
  • Easy wiring, as the physical order of the devices is not relevant and the order of connection of the two Sercos III ports is not important.
  • Software tools include free Sercos II master library, IP protocol library and Sercos monitor.
  • Conformance test software and a Sercos multislave emulator are also available.


  • Use of standard components allows for cost-effective implementation of hardware. Additional active network devices, e.g., switches or hubs, are not required.
  • Master connectivity can be implemented in hardware, hardware and software, or just software.
  • Slave connectivity is based on cost efficient and flexible FPGA devices or integrated multi-protocol chips.


  • Sercos has been an international standard for real-time communication since 1995 (IEC 61491).
  • The Sercos III real-time Ethernet protocol is part of IEC 61158 and IEC 61784. The device profile for drive communication is included in IEC 61800-7.
  • Experts from the Sercos working groups contribute to national and international standardization committees.
  • Twice-yearly free plug-fests give manufacturers the ability to easily test their devices for interoperability with devices from other manufacturers.


  • Sercos is a non-proprietary technology.
  • The specifications are completely disclosed.
  • Membership in a user organization is not required in order to use the Sercos technology.


  • Sercos is an open, international standard.
  • The specifications are maintained and developed by experts in non-proprietary working groups.
  • Good investment protection is provided by backwards compatibility.
  • The technology is continuously developed and adapted to new market requirements.


  • Products from leading automation manufacturers support Sercos.
  • Sercos is widely accepted in many different industries, particularly in demanding applications.
  • Over 3 million Sercos real-time nodes are used worldwide in more than 350,000 applications (and growing).

Worldwide User Groups

  • Active user groups in Europe, North America and Asia support Sercos.


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