The synth in question is a keyboard, not a drum kit, so it probably receives on all channels, but if you want only drums, use channel 10. I've used a 5 pin DIN connector both on the microcontroller side and the synt, which is old enough to have the 5 pin DIN. No fuzz about host or slave.
But you need to study the Yamaha specs. It needs some midi message to be set to receiving midi and performing received midi. Or it might also have a switch for it. Or some key combo while powering on, to set it into the midi receiving mode.