Can You Map a Piano Roll to a Keyboard

Mapped Instrument window in the Logic Pro Environment

The Mapped Instrument window opens when you double-click a mapped instrument icon that you have already added to the Environment, or when you create a new mapped instrument. The rows correspond to input notes, and the columns contain the various parameters available for each note.

Keyboard (Selecting Notes): The keyboard on the left represents the input notes, which can be played by clicking them. You can also select individual notes or note ranges by dragging the mouse over the notes you want to use. To select multiple notes, Shift-click them. Any value alterations apply to all selected notes.
Input Name: In the first column, you can click the input note name (E6, for example), and enter a name of up to 12 characters. Press Return or click outside the field to confirm the new name.

You can initialize the names of the selected notes to:
- Pitch descriptions (C#3, for example) by choosing Initialize > Names as Notes.
- The names of GM Standard drum sounds by choosing Initialize > Names as General MIDI.
If a MIDI region (on a track routed to a mapped instrument object) is displayed in the Piano Roll Editor, the names of the notes being played appear on the vertical keyboard.
Output Note: This column is used to set the output note. This is done by either:
- Double-clicking the note description and editing the text
- Dragging the beam to the right of the output note name
MIDI notes are sent while the value is being changed, allowing you to hear what you're doing. Use the Initialize > Output Notes command to match the output notes of the selected pitches to the input note pitches.
Velocity: Use to set a velocity offset that is added to, or subtracted from, the velocity of the incoming note. Drag the number vertically to create a velocity offset. You can also click the specific point on the beam.

To reset all velocity offsets to 0 (no offset), choose Initialize > Output Velocities.
Channel: Use to set the MIDI channel of individual notes. This lets you play individual sounds from different drum sets in the same sound generator. You normally use the Base setting, which means that the notes are sent on the channel set in the mapped instrument's inspector. If you choose All in the inspector, the channel information of the incoming notes is used. This is useful if you want to place the mapped instrument after a multi-instrument or standard instrument in the signal path.

To set all selected notes to Base, choose Initialize > Output Channels.
Cabling Mapped Instruments: You can send individual notes from a mapped instrument object to (up to) 16 different output cables, allowing you to play sounds from different sound sources. If you select a cable that doesn't exist, the note won't be sent out. The Initialize > Output Cables command resets all cables to #1 (the top outlet of the mapped instrument).
Notation Parameters: The last three columns define the notation parameters of individual notes.
- Head: Use to change the note head.
- Rel. Pos.: Use to alter the relative position of the note on the staff. The pitch isn't altered; only the vertical positioning of the note head on a staff in the Score Editor. Drag vertically to alter the note position.
- Group: As the mapped instrument object is typically used for percussion instruments, click-holding the Group field opens a pop-up menu of grouped drum families: Kick, Snare, and so on. MIDI sound modules can have drum sounds mapped across 127 possible notes, which would result in an interesting staff (to say the least). Assign several related percussion sounds (tom drums, for example) to the Toms group to place all related sounds on a single staff line. As with the relative position, the pitch of grouped notes is not affected by grouping them on a single line.
To neutralize the settings of the Head, Rel. Pos., and Group parameters, choose Initialize > Score Parameters.