OPC UA, MQTT, and Sparkplug B: how they fit together
Three technologies that get compared as rivals but usually work as layers. What each one owns, and how to stop choosing between them.
Companion specification
Domain-specific OPC UA object model (machinery, robotics, instruments…).
An OPC UA extension standardizing object models for a domain — machinery, robotics, process instruments (PA-DIM), machine tools (UMATI), and dozens more. Clients written against a companion spec interoperate with any compliant server.
See also: OPC UA · Information model
Use the concept: Industrial data connectivity: from register to consumer · Industrial data contract template
In depth
OPC UA companion specifications: a guided tour
The base standard models anything; companion specs model your industry. How to find, read, and actually use them.
MTConnect: getting data off the machine tool
Adapters, agents, and streams — how the open machine-tool connectivity standard works and where it fits beside OPC UA.