What is SERCOS III?
SERCOS III stands for SErial Realtime COmmunication System – version 3. It is a real-time Ethernet-based communication protocol used for Motion Control applications in industrial automation, such as robotics, CNC machines, and packaging lines.
SERCOS III combines high speed, precision, and deterministic behaviour with standard Ethernet technology.
⚙️ Characteristics of SERCOS III
- Deterministic and real-time: Very low Latency and predictable cycle times (down to < 1 ms)
- Synchronisation: Precise coordination between servomotors, drives, and the controller
- Ethernet-based: Uses standard Ethernet cabling (100 Mbit/s)
- Dual ring topology possible: Redundancy and fault tolerance
- Open standard: Defined by the SERCOS International organisation
🏭 Applications of SERCOS III
| Application | Description |
|---|---|
| Robotics | Synchronous control of multiple axes |
| CNC machines | Fine coordination between spindle, table, and sensors |
| Packaging lines | Precise timing between motors and sensor data |
| Drives & motion systems | Communication between PLC/DCS and drives |
🔄 SERCOS III vs other protocols
| Protocol | Real-time | Application |
|---|---|---|
| SERCOS III | Yes (deterministic) | Motion control, drives |
| EtherCAT | Yes (faster, also motion) | Motion and I/O |
| ProfiNET IRT] | Yes (IRT mode) | General automation + motion |
| Ethernet IP | Limited real-time | General-purpose, less suitable for precise motion |
🔐 Security & OT integration
SERCOS III operates at layer 2 of the OSI model and is intended for closed industrial networks. When coupling with IT or higher layers (e.g. SCADA, MES, or Cloud), Defense in Depth and network segmentation are recommended.
📌 In summary
SERCOS III is a real-time industrial Ethernet standard for accurate and synchronised Motion Control. It combines the strength of standard Ethernet with the precision required for complex drive and robotics applications.