UaExpert  1.6.2 438
First Steps

This section provides an overview of UaExpert’s GUI and gives an introduction to the most commonly used features. If you haven’t used UaExpert before, this is a good place to start.


The following screenshot shows the window layout of UaExpert when first started. The window titles link to a more detailed description.

Document Window
Can display different view modes. By default, the Data Access View is selected.
Project Window
Can be used to manage multiple server connections.
Address Space Window
Shows the address space of the server which is currently selected in the Project Window.
Attributes Window
Shows the attributes of the node which is currently selected in the Address Space Window.
References Window
shows the references of the node which is currently selected in the Address Space Window.
Log Window
Displays status and error messages.
Default window layout of UaExpert

You can rearrange and resize these windows to your liking and close the windows which you don’t need at the moment. To open a previously closed window, right-click on the toolbar and select the window from the context menu.

Step-by-Step Connect Example

The following paragraph explains step-by-step how to connect to an OPC UA Server with UaExpert. It aims at first-time users.

To add a new connection to an OPC UA Server, click on the + button in the toolbar or choose ServerAdd… from the menu. A new dialog window will open. Double-click on < Double click to Add Server >.

Add Server

A new dialog window will open (see screenshot), asking for a Discovery URL. If you have a Discovery Server running, you can enter its URL. But it’s also possible to enter the URL of the UA Server, as each UA Server has to provide a Discovery endpoint. In our example, we enter opc.tcp://localhost:48010, as we want to connect to Unified Automation’s C++ Demo Server running on the same computer.

Enter Discovery URL

The URL is added to the list, and when expanding the tree, the server and all endpoints it provides are shown (see screenshot).

List of Available Endpoints

As we want to connect with the highest security level available, we pick the endpoint Basic256Sha256 - Sign & Encrypt and confirm with OK. The Server is now listed in the Project Window (see screenshot). The unplugged connector symbol indicates that the connection is not yet established.

Server not yet Connected

To actually connect to the server, click on the plug connector button in the toolbar or choose ServerConnect from the menu. A new dialog window for validating the Server’s certificate will open (see screenshot). After examining the certificate, choose Trust Server Certificate to permanently add the certificate to UaExpert’s trust list. It is also possible to check the box at Accept the server certificate temporarily for this session and choose Continue to not save the certificate in the trust list, or to choose Cancel to reject the certificate.

Check Server Certificate

After accepting the Server’s certificate, we still get the Error BadSecurityChecksFailed (see Log Window and the red sign on the plug connector in the Project Window, see screenshot), because the Server has to trust the Client’s certificate as well.

Connection to Server failed

How this can be done depends on the server. In the case of Unified Automation’s Demo Server we have to move UaExpert’s certificate from pki/rejected to pki/trusted/certs.

The pki folder’s location depends on the operating system on which the Server is running.

Pressing the plug connector button in the toolbar again shows that we are now able to connect to the Server (see screenshot).

Connected to Server


To browse a server’s address space, select the server in the Project Window. A browsable graphical representation of the address space is then shown in the Address Space Window.

Read Attributes of a Node

To read attributes of a node, select it in the Address Space Window. The node’s attributes are then shown in the Attributes Window.

Subscribe to Data Changes

To subscribe to changes of variable values, select the Data Access View in the Project Window (which is selected by default). Drag and drop the node to monitor from the Address Space Window to the Project Window.

Variables with dynamically changing values can be found in the Demo Server’s address space in the folder ObjectsDemo001_Dynamic.