Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Industrial communication

OPC UA server

Also known as: OPC UA server application

German: OPC-UA-Server

In OPC UA, a server is an application that exposes an address space of nodes and provides the OPC UA services with which clients browse and read that information, write values, call methods and subscribe to data changes and events.

  • Industrial communication
  • Standards

In one sentence

An OPC UA server exposes an address space and offers the services clients use to browse, read, write, call methods and subscribe.

Example

The filler of a packaging line runs an OPC UA server on its controller that exposes machine state, fill counters and alarms, so the MES and a quality dashboard can read them.

How it applies

  • Engineering: The server decides what is visible: which variables, objects, methods and events appear in its OPC UA address space, and in which structure. Implementing a OPC UA companion specification makes that structure predictable for clients.
  • Performance: Controllers with embedded servers have limits on sessions, subscriptions and monitored items. Many clients sampling fast can load the controller.
  • Security: The server offers endpoints with one or more OPC UA security policy settings, holds an application certificate and a trust list, and decides which users may read, write or call methods. These settings have to be configured; a server with an open endpoint and anonymous write access is a real risk.
  • Documentation: The documentation team documents the endpoint URLs, supported profiles and companion specifications, the namespace, the exposed nodes with meaning and units, the user roles and the certificate handling.

OPC UA server vs. device

The server is software, not a device. One controller can host a server, an edge gateway can host a server for several machines, and one PC application can be server and client at the same time.

By knowledge.aitechdoc.world · Published September 28, 2026 · Last reviewed

Source: IEC 62541-4 / OPC 10000-4, OPC Unified Architecture — Part 4: Services

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Blog and are not part of any standard.

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