The NMEA 0183 Multiplexer (hereinafter Multiplexer or Device) is a configurable NMEA 0183 and SeaTalk multiplexer. The Multiplexer has six configuration presets with different port speeds and routing schemes. Presets can be selected by pressing the Device’s hidden button (a paper clip is required, supplied with the Device). This makes installation very easy: select a suitable preset from Appendix B and set it up with a few clicks!

The Multiplexer has five physical NMEA 0183 ports (five inputs and three outputs) with configurable speed from 300 to 115200 baud. This allows organization of data exchange between multiple devices with different speeds. Multiple physical listeners can be connected to the Multiplexer’s outputs. Port #4 is galvanically isolated and has five terminals: four data terminals (TX+, TX-, RX+, RX-) and a dedicated ground (also isolated from other ports and Multiplexer’s ground).

SeaTalk is a proprietary binary protocol of Raymarine company. It allows co-existence of multiple devices on the bus, so the Multiplexer has only one SeaTalk port. A bi-directional converter between SeaTalk and NMEA 0183 supports all known SeaTalk datagrams, including autopilot. This allows controlling SeaTalk autopilots from NMEA 0183 chart plotters and marine apps.