I just connected my old Clavinova to Logic X. I bought a Midi to Usb cable (TIE Studio Midi 1i1o).
My clavinova was bought long time ago - i think around 10 years - so it haven't got a usb- connection.
Be sure to connect as said before - do the "opposite" to what you think is correct
- Midi OUT in clavinova goes to cable connection labeled "IN". and the IN on the clavinova goes with the "OUT" connection on the cable.
Then there is the switch on Clavinova. My clavinova is 10 years old but i think its the same for most . "Midi,Pc-1, Pc-2,MAC". What i read its the "TO HOST" connection för the computer-modes (though different cable). I switched mine to "MIDI" - plugged the usb to my MacPro. It started to blink red - and i opened Logic and could play my Clavinova in Logic pro X.
Hope this is helpful.
This link helped me - it has all kinds of connections explained to clavinova.
"How do I connect the Clavinova to a computer? "
The midi section
(2. Using a MIDI interface device and the Clavinova’s MIDI connectors )
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http://www.dannychesnut.com/Music/Yamaha/Clavinova/Information/ComputerConnect/C laviPC_E.pdf