Overview

This tutorial will guide you through how to set up a connection between a generic instance such as a PLC and how to expose the data from the instance on an OPC-UA server through SIA Connect. 

This example will show how to configure a OPC-UA server for a Mitsubishi MELSEC PLC.

Connectors used in this guide

Use this guide for learning how to install connectors.

The following connectors are used for this guide:

• OPC-UA Server - Used for setting up the OPC-UA server
• Mitsubishi MELSEC - Used as an example for a PLC

Creating the OPC-UA server

First thing we should do in order to expose data from a PLC on our OPC-UA server, is to set an instance using the OPC-UA server connector. This is done so we can add the data points from the PLC afterwards, using items in the instance.

Use the following guide to learn about how to set up an instance and items within the OPC-UA server connector.

Start out with creating an instance for OPC-UA server connector, in the example given below there is no key or login detail used. It will simply make an OPC-UA server on the “*Device_IP*:4840” which has no login details required.

Create an item to initialize the instance and to be able to expose the data from another connector through mapping. This item will be your direct path to exposing data to the OPC-UA server.

Creating PLC tags to send to the OPC-UA server

Using any compatible PLC you have available, setup the corresponding connector and create an instance. For a list of all PLC's that are compatible with SIA Connect look here.
For a guide to your specific compatible PLC look through this menu.

In this example a Mitsubishi Q02 is used as the PLC wherein tags are written to. You can create the items for the tags using the setup view, this will allow you to easily create multiple items at a time. Switch out of setup view again to save your items. Here memory address D1 and D2 is used.

Mapping PLC data to the OPC-UA server

Create a mapping between the PLC data items and the OPC-UA item.

The mapping will allow us to link the PLC data to the item on the OPC-UA server which exposes the data. Here we can simply link all PLC items to the same OPC-UA item.

Learn about how to create mappings through this guide.

The first step in exposing PLC data through an OPC-UA Server is to create an instance using the OPC-UA Server connector.

Verify the connection to the OPC-UA server

To verify that we have a connection to the OPC-UA server and the PLC data is being exposed correctly, we will update the data in the tags using items, and connect to the OPC-UA server and check that the tag is available.

Under the instance for your PLC, change the values of your items.

Connect to the OPC-UA server through your preferred OPC-UA explorer tool. In this example UaExpert is used.

You should now be able to see the simulated data through the OPC-UA server.

This way of setup will only allow data flow in one direction. In the next example it will be shown how to do the set up if you want bidirectional data flow.

Create bidirectional mapping for PLC tags to the OPC-UA server

To get a bidirectional mapping, you can either add a new mapping using the same or new items from the PLC. Or simply edit the mapping that is already made.
The only difference in the setup is that the box for “Bidirectional synchronization” should be checked.

It is now possible to read/write directly to the PLC through the OPC-UA explorer tool.

You now have a working connection between your PLC and the OPC-UA Server, with data successfully exposed and accessible through an OPC-UA explorer tool. By enabling bidirectional synchronization, you can also write values back to the PLC from the server. From here you can continue to add more tags from your current PLC, or add more instances to other PLC's and expose their data to the OPC-UA server the same way.