MIDI Connections
To play back and record MIDI data from your MIDI device, for example, a MIDI keyboard, you need to connect the MIDI ports.
Connect the MIDI output port of your MIDI device to the MIDI input port of your audio hardware. This way, the MIDI device sends MIDI data to be played back or recorded inside your computer.
Connect the MIDI input port of your MIDI device to the MIDI output port of your audio hardware. This way, you can send MIDI data from Nuendo to the MIDI device. For example, you can record your own playing, edit the MIDI data in Nuendo, and then play it back on the keyboard and record the audio that is coming out of the keyboard.