====OPC-UA Example====

**OPC-UA** is an industrial protocol, designed to make a unified method of exchanging industrial data between systems.

Most industrial recording systems support OPC-UA, along with a number of SCADA systems and HMIs.

It isn't often supported directly in a sites PLCs, but protocol converters such as those provided by RedLion allow you to read OPC-UA data and write it into a huge range of PLCs and other pieces of industrial hardware.

===Viewing OPC-UA Data===

There are a variety of OPC-UA clients available and several of them are free (although most require you register on the creators website).

We tend to use [[https://www.unified-automation.com/products/development-tools/uaexpert.html|UAExpert]] by Unified Automation - it's free, simple and highly compatible with a wide range of systems.

Below is an example of connecting to a UA server...

===Adding a Server===

{{UAExpertUI.png}}

Right-click the **Server List** at the top-right and choose **Add...** from the pop-up menu.

{{UAExpertAddServer.png}}

Double-click where it says 'Double-Click To Add Server'.

{{UAExpertURL.png}}

Enter the url in the form...

   opc.tcp://<servername>:<portnumber>

For instance, if you're running an OPC-UA server on port 2244 on your local computer, you'd use **localhost:2244** as the address.

This will //add the server to the list// but you'll still need to select //how// you'd like to connect to it. 

Open the new entry in your server list and navigate through the options below it until you find the real OPC-UA server (a single server might have several different OPC-UA services, and each of those can have different connection methods and authorisation schemes).

When you've chosen the connection method and authentication you want to use (using the method marked as **None** - **None** is always simple - this means that you can connect without authentication), the window will close and the server will be added.

===Connecting===

The server has been **added**, but we aren't **connected**.

Right-click the server and chose **Connect** to actually establish the connection.

{{UAExpertConnect.png}}

===Browsing for Points===

Once connected, the **Address Space** list will fill in with the content of the UA server. You can navigate through folders (yellow) and objects (boxes) until you find the individual //tags// (green) that represent specific points of data.

{{UAExpertNav.png}}

Drag these green tags over to the **Data Access View** to see the values. They'll update automatically as the data changes.