Assigning MIDI Track Output
Pro Tools lets you assign specific MIDI ports and channels to a MIDI track output. The default selection of none sends MIDI data to no port on any channel. Use the MIDI Output selector to specify a MIDI port and channel for output.

MIDI tracks in Pro Tools cannot contain multiple channels of MIDI data.
To assign a MIDI track (and all its clips) to a specific MIDI device channel:

Click the track’s MIDI Output selector and assign a port and channel for MIDI output. Channels already assigned to another track appear in bold.

In the Edit window, select I/O from the Edit Window View selector to access any track’s Output selector.
To assign multiple destinations to a single MIDI track:

Control-click (Mac) or Right-click (Mac or Windows) the MIDI Output selector and select additional channels from any device.