You can connect Cortex/XB8000/Vision NMEA 2000 port to Raymarine SeaTalk NG backbone. What you need is a Raymarine DeviceNet cable and an available tee on the backbone. Please refer the link below
http://www.raymarine.eu/view/?id=5536&collectionid=9&col=1617
The cable is "A06045 - Raymarine Female Devicenet (NMEA 2000) to SeaTalkNG Adapter Cable"