# Configure an OPC UA Server

Perform the following steps to configure an OPC UA Server device.

1. In the Project Explorer, search for the Devices > Communications > OPC UA node.

2. Right-click the OPC UA node, and then left-click Add 'OPC UA Server' Device.

3. The Parameter Configuration dialog appears. Fill the available properties as applicable.

   Property | Description
   Name | The user-specified name used to reference the server device in the Cognex Designer project.
   Port | Specifies the port to be used as the base address of the OPC UA server device. OPC UA client applications will communicate with the OPC UA server device through this port.
   Endpoint Port | Specifies the endpoint URL, used by the OPC UA Discovery Server on the network. Configure this property if Cognex Designer is running on a machine with multiple OPC UA servers.

4. Click Accept once all properties have been configured.

Once you are done, the configured OPC UA server automatically goes online with the configured properties, and exposes all compatible tags and published $ functions in its address space that use a type which is supported by the OPC Foundation .NET implementation. Successful connection is indicated with the icon, while connection problems are shown with .

Note:

- Cognex Designer supports only one OPC UA Server device per project.
- You can connect to the OPC UA Server device with a OPC UA client while the project is under development (that is, it is in Program Mode). However, in this case, you cannot update tags or functions that are exposed with the OPC UA server device.

## Troubleshooting

If the OPC UA server device fails to connect due to a "BadSecurityChecksFailed" issue, it is likely that the issued Cognex Designer OPC UA Server certificate has expired.

To fix this, you will need to delete the files and folders located in %ProgramData%\Cognex\Designer\Certificates\own before deleting and re-adding the device in Designer. Connecting the device after deleting the old certificates automatically generates a new certificate that will expire after 10 years.