Overview of OPC Unified Architecture (OPC UA) and Its Industrial Applications

OPC is an interoperability standard for safe and reliable data exchange in industrial automation and other industries, independent of platform and supported by the OPC Foundation. It defines client‑server and server‑server interfaces for real‑time data, alarms, events, historical data, and more.

The original OPC specifications, released in 1996, abstracted PLC‑specific protocols (e.g., Modbus, Profibus) into a standardized interface, enabling HMI/SCADA systems to communicate with devices via a "middle‑man" and fostering a broad ecosystem of interoperable products.

Initially limited to Windows (hence the name OPC – OLE for Process Control), the specifications are now known as OPC Classic and are used in manufacturing, building automation, oil & gas, renewable energy, utilities, and other sectors.

With the rise of service‑oriented manufacturing systems, new challenges in security and data modeling emerged, prompting the OPC Foundation to develop the OPC UA specification, a platform‑independent, service‑oriented architecture that offers a rich, extensible, and future‑proof platform.

OPC UA is currently installed in over 17 million machines worldwide. The article presents case studies illustrating its practical benefits:

Transportation: DB‑MAS (Deutsche Bank Meldesystem) provides a standardized communication structure for remote monitoring of alarm systems, wind sensors on bridges and dams, and railway tunnel safety devices.

Automotive: Softing’s embedded OPC‑UA server gateway (echocollect UA) connects embedded devices to IT systems, supporting data access for over 50 controller types in process, manufacturing, and quality domains.

Chemical Manufacturing: SAFCO (Saudi Arabian Fertilizer Company) isolated plant networks after severe cyber‑attacks in 2012, demonstrating OPC UA’s role in secure plant integration.

Energy Monitoring: The city of Aachen (Germany) uses Beckhoff‑based e2watch for fast‑response energy monitoring of water, electricity, and heat consumption.

Food & Beverage: Weber Maschinenbau GmbH employs OPC‑UA for controlling slicing machines, food robots, and other processing equipment.

Oil & Gas: Neste Jacobs integrates OPC‑UA into advanced process control and real‑time databases, and extends the NAPCON® simulator with OPC‑UA‑based communication.

Water Treatment: Distributed embedded controllers form intelligent networks for drinking‑water and wastewater plants, using OPC‑UA for secure M2M interaction.

The German Federal Office for Information Security (BSI) performed a security analysis of OPC UA (protocol version 1.02), including threat modeling and detailed review of specific specification sections (parts 2, 4, 6, 7, 12). The OPC Foundation’s security workgroup evaluated the findings, addressed minor issues, and recorded open items in the Mantis issue tracker for future resolution in upcoming OPC‑UA releases.

OPC UA is a platform‑independent, service‑oriented architecture that incorporates all functionalities of OPC Classic while adding enhanced security and scalability. The specification is divided into multiple parts covering overview, security model, address space, services, information models, mappings, profiles, data access, alarms & conditions, programs, historical access, discovery, aggregation, PubSub, and various companion specifications for domains such as AutoID, oil & gas, FDT, device information, PLCopen, ISA‑95, AutomationML, and analytical instruments.