As a reminder, if the Omniscan is on your network, you can use the "Detect Devices" button to autopopulate the fields.
After saving, add the NMEA source as a Generic GPS Device:
You can also connect to NMEA sources via UDP with IP address and port
Add a new session with both devices:
Here's where you should be at:
With the Omniscan and gps powered and connectable, you should be able to connect to this session in discovery and use the Omniscan with heading and position.