To connect Ignition to an Allen-Bradley ControlLogix device

Go to the Configure section of the Gateway webpage.
Scroll down and select OPC-UA > Devices.
On the Devices page, find the orange arrow and click on Create new Device.
On the Add Device Step 1: Choose Type page, select Allen-Bradley ControlLogix, and click Next.
On the New Device page, leave all the default values and type in the following fields:
Name: ControlLogix
Hostname: type the IP address for the PLC, for example 10.20.4.50
Click Create New Device.
The Devices page is displayed showing the ControlLogix device is added to Ignition. The Status will show as Disconnected and then Connected.
To see all the tags, go to OPC Connections > Quick Client in the Configure section, on the OPC Quick Client page expand the ControlLogix folder and in the Global folder you can see all the tags.

Next ...