If your NMEA 0183 Listener is not showing any data when connected to the NMEA 0183 output of an NGW-1, the first step for fault finding should be to see if the NGW-1 supports the conversions you need.

For more information on the steps taken when investigating this issue, along with the supported conversions for the NGW-1 v2.660 firmware, visit the following article:
https://www.actisense.com/knowledge-base/nmea-2000/ngw-1/nmea-0183-device-not-receiving-data-from-ngw-1/