Automation and IIoT
What is OPC UA (OPC Unified Architecture)?
OPC UA is a secure, platform independent standard for exchanging industrial data with built in information models. How it works, PubSub, and OPC UA versus MQTT.
Quick answer
OPC UA (OPC Unified Architecture) is an open standard from the OPC Foundation for exchanging data between industrial devices and software securely and independently of vendor or platform. Beyond moving values, it describes what the data means through information models, so a client can discover a machine’s structure.
Updated 30 October 2026. Written by the Ajinkya Technologies engineering team, reviewed by Amey Kadle.
OPC UA explained
OPC UA, published as IEC 62541, succeeded the older Windows based OPC standards. It runs on many platforms from embedded controllers to cloud servers and includes security by design: application certificates, encryption and user authentication.
Its distinguishing feature is information modelling. A server exposes not just tags but objects with types, properties and relationships, for example a machine with spindles, axes and counters. Industry groups publish companion specifications that standardise these models for machine tools, plastics machinery, packaging and many other sectors, so different vendors’ machines can be understood the same way.
OPC UA supports the classic client server pattern, where an MES or SCADA reads from and writes to a server, and a publish subscribe pattern that can run over MQTT or UDP for one to many data distribution. In practice many plants use OPC UA at the machine and edge, and MQTT to move data from the edge to a broker or the cloud.
Key concepts
- Open standard, IEC 62541
- Security built in: certificates and encryption
- Information models, not just tags
- Companion specifications per industry
- Client server and PubSub patterns
Questions
What is the difference between OPC UA and MQTT?
OPC UA is a full interoperability framework with information models and security. MQTT is a lightweight publish subscribe transport. They are often combined: OPC UA at the machine, MQTT from the edge to a broker.
Do our machines need to support OPC UA?
Not necessarily. Many modern PLCs include an OPC UA server; older equipment can be exposed through an edge gateway that converts its native protocol to OPC UA.
Is OPC UA secure?
It provides strong security mechanisms, but they must be configured: certificates managed, encryption enabled and access restricted, as part of an OT security design.
References
How we help with OPC UA
We use OPC UA to read machines and PLCs for MES, OEE and SAP integration, and expose older equipment through edge gateways when it has no OPC UA server.
Interactive 3D demo with simulated data: cut the network and watch the edge store and replay.
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