OPC UA explained simply
Imagine your machines and systems as people who all speak the same language – regardless of origin, manufacturer or platform. That is what OPC UA (Open Platform Communications — Unified Architecture) achieves: it is an open, vendor-neutral communication standard that allows machines, sensors, controllers and IT systems to communicate securely and platform-independently with each other. Whether Windows, Linux or embedded systems – with OPC UA the language barrier disappears, and your automation finally becomes understandable and flexible.
Background information
OPC UA is a modern, platform-independent standard for data exchange in industrial control and automation systems, developed by the OPC Foundation and standardised as IEC 62541.
Unlike its predecessor, OPC Classic, OPC UA is platform-independent, scalable, secure and supports different communication models (client-server and publish/subscribe). It is therefore the basis for networked production in the sense of Industry 4.0.
A comprehensive OPC UA ecosystem consists of reference implementations (e.g. open62541, Eclipse Milo), industry-specific Companion Specifications, security layers, middleware and platform integrations. OPC UA thus covers the entire range from embedded devices to cloud platforms.
Companion Specifications & applications
To ensure that OPC UA standardises not only the language but also the vocabulary of machines, there are so-called Companion Specifications.
- Definition: Companion Specifications are industry-specific extensions that define how data models in particular industrial sectors are structured and interpreted.
- Benefit: They create interoperability between devices from different manufacturers which would otherwise “speak OPC UA” but use different terms.
Examples of Companion Specifications:
- Robotics CS: Uniform data models for robot controllers.
- CNC CS: Standardised interfaces for machine tools.
- PackML CS: For the packaging industry, defines common state models and control commands.
- Energy CS: For energy management, smart grids and charging infrastructures.
Practical application:
A manufacturing company that uses machines from different manufacturers can, thanks to Companion Specifications, retrieve all data in a uniform format – whether from robots, CNC machines or energy systems. This makes integration, monitoring and analysis considerably easier.
Security model in OPC UA
One of the most important unique selling points of OPC UA is its integrated security model. In times of cyberattacks and industrial espionage, it is indispensable that machine communication not only works, but is also protected.
Central security mechanisms:
- Authentication: Devices, applications and users must identify themselves unambiguously (e.g. via X.509 certificates or username/password).
- Authorisation: Access controls regulate which rights individual users or systems have.
- Encryption: Data is protected during transmission (e.g. via TLS or asymmetric cryptography).
- Integrity: Digital signatures ensure that messages have not been tampered with.
Role-based security concept:
OPC UA supports role-based access rights, which allow both granular control (e.g. reading, writing, configuration) and simple management in large production environments.
Firewall and IT friendliness:
Since OPC UA works via standardised ports (e.g. HTTPS), it can be easily integrated into existing IT security architectures.