I dont have a Merc, but heres what I had to have to get the HB to pick up data from the Yamaha SHO ECM. Interface cable from ECM to NMEA 2000 backbone, a “drop” (tee) and terminator, the HB “black dongle” to convert the NMEA signal to an ethernet signal, the 5 port ethernet box from HB, ethernet cable to get to the front unit. I could never get the HB Helix 7 SI GPS Gn2 to provide engine data, other than RPM and Engine Temp, so swapped that unit to the front with the HD transducer, and put a Helix 10 Mega SI gn2 in the dash. Also installed an electronic sensor on the engine for water pressure reading to be fed into the ECM. In “gauge view” (which eats the entire screen, not a layover) I can now see RPM, Engine Temp, Water Pressure, Oil Pressure, GPH in real time, and could see Trim if I connected two wires together on the engine, but that would kill my analog gauge on the dash, so I havent gone there yet. HB is NOT as friendly as Lowrance to display engine data without all those “dongles” for lack of a better word. To get Speed on Gauge View, I think Ill need an external GPS puck. Or, I may be able to get it from the front unit, but havent dug into that function yet. It aint easy to set it all up, as the menu system is not particularly intuitive.The Helix units have 3 different gauge views…one is strictly digital, one is a combo of digital and “digital analog), and then you have the “dashboard” gauge view that is the one I prefer and have on a preset button. Its sort of looks like a car dash and is relatively easy to see the vitals. The three preset buttons on my 10 are SI/DI/SD; Lakeview Map/SI/SD; Gauge View. Of course, the SI/DI is useless when running, but two of the views always have the “regular” shoot thru hull view for depth at speed.
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