For example, you can set your IP address of your OnPC to 192.168.0.1 , subnet mask 255.255.255.0 and your 2port node/NSP/NPU as 192.168.0.2. Your Catalyst IP address can 2.0.0.10, subnet mask 255.0.0.0. Start a network seasion, add your 2port node/NSP/NPU to your session. Enable output via Artnet in your OnPC, you should be able to control your Catalyst.