Dave: What do you want the ST60 Multi to do?This instrument is a repeater instrument, and does not generate any data on its own - it only displays the data from another instrument (e.g., wind, depth, speed,
gps). The primary communications means is through SeaTalk,
Raymarine''s proprietary network protocol. If you want to display NMEA data passing over a SeaTalk network on a non-Seatalk instrument, i.e., your Horizon
GPS Chartplotter, you will need a SeaTalk to NMEA converter box.
Raymarine will gladly sell you one for a couple of hundred dollars. I have one set up and connected to my laptop through the serial ports and receive the full NMEA stream of data - all having been converted from SeaTalk through the converter. However, you still need a sender unit to generate the data.