Send MIDI messages from Logic Pro for Mac to another music app
Logic Pro for Mac features a virtual MIDI device called Logic Pro Virtual Out that you can use to send MIDI messages to another music app installed on your Mac. When you choose Logic Pro Virtual Out as a MIDI input on any MIDI-capable music app on your Mac, the app receives MIDI messages from Logic Pro at the chosen input.
Also, most music apps (including GarageBand for Mac) that receive MIDI on all channels will receive MIDI messages from Logic Pro Virtual Out, even if they do not offer the ability to choose a MIDI input.
In Logic Pro for Mac, the Logic Pro Virtual Out virtual MIDI device is available in the following locations:
The Destination pop-up menu in the MIDI Synchronization project settings.
The MIDI Output pop-up menu in the Track inspector when an external MIDI track is selected. See Overview of MIDI channel strips.
The MIDI Destination pop-up menu in the External Instrument plug-in. See External Instrument.
The MIDI Destination pop-up menu shown in the Details area of the New Tracks dialog when you select either MIDI or Pattern and then select External MIDI. See Create a software instrument track to use with external MIDI.