The MiniPlex-3PRO NMEA 0183/2000 multiplexer/gateway enables connection of multiple NMEA 0183 devices to an NMEA 2000 and an Ethernet network. Conversion is provided between NMEA 0183 and NMEA 2000 in both directions and a routing table gives full control over which data is routed where. The Ethernet port is used to transmit NMEA 0183 data onto an Ethernet network and also to receive NMEA 0183 from the same network, to be routed to one or more NMEA 0183 ports and to the NMEA 2000 network.