Fast Data eXchange

FDX, short for Fast Data eXchange is a proprietary maritime communication protocol by Nexus Marine AB.

It describes how data points from sensors are to be sent across an RS485 serial bus to displays. FDX was originally developed in the 1990s, and is now mostly seen as a legacy protocol. The GND10 gateway from Garmin translates FDX into NMEA 2000, to be able to continue using Nexus sensors on more recent NMEA 2000 networks.

Data is transmitted asynchronously with 1 start-bit, 8-data-bits, 1 parity-bit, two stop-bits in 9600 baud. Data is exchanged in packets. There are two types of packets, data packets that carry the actual data that i transmitted, and New-Sender-Packets that transfer the right to send to the next sender.