What is OPC-UA?
OPC-UA (Open Platform Communications — Unified Architecture) is an industrial communication protocol developed by the OPC Foundation. Unlike classic protocols such as Modbus or Profibus, OPC-UA is platform-independent, service-oriented, with built-in security and capable of transporting not just data but also information about the structure and meaning of that data (semantics).
OPC-UA is the protocol recommended by the Industry 4.0 initiative (Plattform Industrie 4.0) and by IEC 62541, and is adopted by virtually all modern PLC and SCADA manufacturers: Siemens, Beckhoff, Rockwell, Schneider, Ignition and hundreds more.
Client-server architecture (and pub/sub)
OPC-UA works primarily in a client-server model: the OPC-UA server exposes an Address Space with variables, methods and events. Clients subscribe to the variables they are interested in and receive automatic updates when they change. The latest specification also includes the publisher-subscriber (Pub/Sub) model, useful for IoT industrial architectures with MQTT or UDP.
Security in OPC-UA
Security is one of OPC-UA's great differentiators: X.509 certificate or username/password authentication, TLS 1.2/1.3 encryption, message signing for data integrity, and access control per variable or node in the Address Space.
Why is it the Industry 4.0 standard?
- Manufacturer and OS independent: Siemens, Beckhoff and Rockwell OPC-UA servers communicate identically
- Transports semantics: not just the value, but what it is and how it relates to other variables
- Secure by design: meets IT/OT cybersecurity requirements
- Scales from microcontrollers to servers
OPC-UA vs classic protocols
| Feature | Modbus TCP | Profinet | OPC-UA |
|---|---|---|---|
| Manufacturer independent | Yes | No | Yes |
| Built-in security | No | Basic | Yes (TLS, certs) |
| Data semantics | No | No | Yes |
| IT/OT convergence | Difficult | No | Designed for it |
Want to integrate your systems via OPC-UA? Talk to our team.