OPC UA (OPC Unified Architecture) is an open standard for exchanging data between industrial machines, controllers and software. It lets an MES, dashboard or ERP integration read values such as temperatures, counters and machine states from PLCs and other equipment, regardless of the brand, in a secure and structured way. OPC UA is maintained by the OPC Foundation and published as the international standard IEC 62541.
What Makes OPC UA Different
- Information models: data is not just a list of values but a structured model with types, units and relationships, so software understands what a value means.
- Platform-independent: unlike its predecessor OPC Classic, which depended on Windows technology, OPC UA runs on any operating system, from embedded devices to cloud servers.
- Security built in: authentication with certificates, encryption and signing of messages.
- Client/server and publish/subscribe: software can query a machine on demand or subscribe to changes and receive them as they happen.
- Companion specifications: standard models for machine types and industries, so similar machines describe their data in the same way.
OPC UA in Practice
Many modern PLCs and machines include an OPC UA server. Software connects as a client, browses the available nodes, and subscribes to the values it needs, such as cycle counts, states and alarms. Older machines without OPC UA can often be connected through a gateway. The data then feeds OEE dashboards, SPC, maintenance planning and production reporting. It sits alongside other industrial protocols and systems such as MQTT and SCADA.
How SemBricks Uses OPC UA
We build software that collects machine data over OPC UA and turns it into output, downtime and quality figures, see machine data processing, maintenance scheduling and quality control software.
Frequently Asked Questions
What is the difference between OPC UA and OPC DA?
OPC DA belongs to OPC Classic and relies on Windows DCOM. OPC UA is its platform-independent, more secure successor with richer information models.
OPC UA or MQTT?
OPC UA is strong at structured access to machines on the shop floor; MQTT is a lightweight messaging protocol popular for sending data to the cloud. They are often combined.
Can older machines be connected?
Often yes, through gateways that translate older protocols to OPC UA, or by reading the PLC directly.