Yamaha, Garmin and NMEA0183 question

I'm looking for an economical way to check my engine RPM's. Both my 2014 F90 Yamaha and my Garmin 93SV have a two wire NMEA connection. The Garmin has the capability to act as the engine's gauges. Can I simply connect the wires from the engine to the graph and then read engine RPM's on the graph? It's probably more complicated than that, but if it'll work that way, I'd save a couple hundred bucks by not buying NMEA 2000 stuff or a dedicated tach. Thanks for the help!

Something like this will work. Amazon.com

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Originally Posted by Barnacle Bill

Something like this will work. Amazon.com

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I ordered that tach right after you posted yesterday evening. It got to my house about 2 pm today (how do they do that?). According to the little gadget, my motor was turning 6020 rpm at wot with just me in it. After filling the live well/bait tank, it turned 5970. I think I need a little bigger prop.