| | El-cheapo Yamaha command link to Garmin NMEA 2000 cable works
I have been using the Yamaha command link gauges for a while now and they are great but I recently picked up a Garmin 5212 and wanted to see if I could use the gauges on the 5212. Supposedly the command link is NMEA 2000 so I wanted to see if I could build an interface cable between the two networks with parts I already had. No hundred dollar cable or gateway for me.
Since both networks are end to end terminated, in theory the easiest way to join the two networks is to merge them into one main bus by removing one terminator on each network and building the cable that joins the two. Before I did that, I wanted to verify that both the garmin and yamaha terminators were 120 ohm. After taking the command link terminator, I found a 120 ohm resistor over the two bus lines as expected.
To make it easy, I removed the resistor on the Yamaha terminator and took a section of ethernet cable I already had and soldered two wires to gain access to the command link network (drilled a hole on the cap of the terminator to route wires). On the other end, I soldered the two wires to a 2-pin connector I also had. Now the cable was done and all I had to do is plug the two pins into the garmin network bus lines where one of the terminators used to plug in. The modified Yamaha terminator cable was plugged into the Yamaha hub.
The moment of truth came and I powered up the Garmin and the motor. Nothing showed up on the 5212 but then I thought about pin positions of the Yamaha terminator and figured they might be different from the other ports on the Yamaha hub. Turns out I was right as once I reversed the input pins on the Garmin side, I got engine data on the 5212.
Attached are pics of the cable and gauges in action. Everything seems to work great and the "upgrade" was basically free but required technical expertise. I also double checked the bus resistance with the merged network and it was 60 ohms so perfect.
If I had an extra NMEA 2000 drop cable, I would have cut that and used it instead of the two pins but I didn't have one. Works either way...
PM me if you have any questions. If you attempt to try this, do this at your own risk. I am providing this information to benefit others.
Last edited by wugubob; 08-08-2012 at 12:00 PM.
Reason: added more info