Transfer MIDI information between apps
In Audio MIDI Setup, use the IAC driver to let MIDI apps transfer information to each other. For example, you might have a MIDI keyboard app send its MIDI data to a MIDI synthesizer app.
To allow MIDI apps to transfer information, you need to set up at least one bus (sometimes referred to as a port). One app uses the bus as a destination to send information, and another app uses it as a source, to receive information.
Choose Window > Show MIDI Studio.
In the MIDI Studio window, double-click the IAC Driver icon.
In the IAC Driver Properties window, select “Device is online” to turn on the driver.
Select a bus in the Ports list, specify the number of MIDI input and MIDI output connectors, then click Apply.
Do any of the following:
Add a bus: Click the Add button
.Remove a bus: Select it in the Ports list, then click the Remove button
.Rename a bus: Double-click it in the Ports list, enter the new name, then press the Return key.