Overview

This chapter describes the steps required to configure the variables in the TwinCAT OPC UA Server namespace for Data Access (DA).

Data Access is an OPC UA function that describes the representation and use of variable values. For example, this is about the service functionalities, how an OPC UA client can access variable values.

The TwinCAT OPC UA Server can provide variables from all TwinCAT real-time environments. These include, for example, the TwinCAT PLC, TwinCAT 3 C++, TwinCAT 3 Matlab/Simulink® or a TwinCAT I/O task. The server can access several real-time environments and provide their symbolism in its address space.

Basis for further functions The Connection with the runtime and enabling symbols for Data Access is the basis for other functions, such as Historical Access and Alarms & Conditions. Please make sure you are familiar with the settings required here.

The different real-time environments do not necessarily have to be on the same system, but can be distributed across different controllers. In this case, an ADS route must be set up for each system. The following figure illustrates this relationship.

In the TwinCAT OPC UA Configurator, the Data Access configuration can be carried out in the Data Access tab. All connected real-time environments are displayed there as a separate "device". The chapter Connection with the runtime describes how to add data access devices and which parameters are required for this. You can then start with Enabling symbols.