OPC UA

What is OPC UA?

OPC UA (Open Platform Communications Unified Architecture) is a communication protocol designed as a universal standard for data exchange in industrial automation. It was developed by the OPC Foundation as the successor to earlier OPC Classic specifications (OPC DA, OPC HDA, OPC AE), eliminating their limitations - primarily the dependency on Microsoft DCOM technology.

OPC UA offers a data model based on address spaces that allows describing not only the values of process variables, but also their context - data type, unit, range, relationships to other variables. This makes OPC UA more than a transport protocol - it is a platform for modelling industrial information.

The protocol runs on multiple platforms (Windows, Linux, embedded devices) and supports various communication models: client-server, publish-subscribe (Pub/Sub) and cloud access. It is increasingly chosen as the communication standard in Industry 4.0 concepts.

Why does it matter?

Unlike older industrial protocols (Modbus, DNP3), OPC UA has built-in security mechanisms: authentication (X.509 certificates), communication encryption (TLS), node-level authorisation and operation auditing. This makes it one of the more secure protocols available in the OT environment.

However, deploying OPC UA alone does not guarantee security - protection mechanisms must be properly configured. Implementation flaws, weak certificates or lack of session management can negate the protocol’s advantages. Organisations should treat OPC UA as an element of a broader OT security strategy, not as a standalone solution.

Related topics

• Modbus
• SCADA
• ICS
• IEC 62443