OPC UA Server Overview

Overview

The OPC Unified Architecture server (OPC UA server) allows the M262 Logic/Motion Controller to exchange data with OPC UA clients. Server and client communicate through sessions.

The items of data (also referred to as symbols) to be shared by the OPC UA server are manually selected from a list of the IEC variables used in the application.

The OPC UA server supports Read and Write access as well as the subscription model. When using the subscription model, the OPC UA server reads the values of symbols from devices at a fixed sampling rate, places the data in a queue, then sends them to clients as notifications at a regular publishing interval. The sampling interval can be shorter than the publishing interval, in which case notifications may be queued until the publishing interval elapses.

Symbols that have not changed value since the previous sample are not re-published. Instead, the OPC UA server sends regular KeepAlive messages to indicate to the client that the connection is still active.

User and Group Access Rights

Access to the OPC UA server is controlled by user rights. Refer to User Rights.

OPC UA Services

The following OPC Foundation Profiles and facets are implemented:

  • OPC UA Micro Embedded Profile 2017

    • Core 2017 Server Facet

    • UA-TCP UA-SC UA-Binary

    • Embedded DataChange Subscription

  • Security Category

    • SecurityPolicy – Basic256Sha256

    • SecurityPolicy – Basic256

The following functionalities are supported:

  • Address Space Model

  • Attribute Services

  • Base Information

  • Discovery Services

  • Monitored item Services

  • Protocol and Encoding (TCP UA Binary)

  • Security

  • Session Services

  • Subscription Services

  • View Services