# OPC UA Server

Note: This feature is only available if the optional OPC UA Server plugin has been selected for installation in the Cognex Designer setup.

The OPC UA device allows you to set up a communications server device that the Cognex Designer project can use to interact with an OPC Unified Architecture (UA) client application.

OPC UA is a free, cross-platform machine to machine communication protocol for industrial automation, offering robust security solutions and an integral information model, allowing users to model their complex data into an OPC UA namespace to take advantage of the protocol's rich service-oriented architecture.

When this plugin is installed and used in a Cognex Designer project, you can interact with your deployed vision application through an OPC UA client application either by reading and writing supported Tags, or by executing the published and supported $ functions of the project (see the OPC UA Server – Exposing Tags and $ Functions topic for more information). The protocol is represented in Cognex Designer with the OPC UA Server Device.