10.6

Table Of Contents
123Logic Pro User Guide
For keyboard controllers without tone generators: You only need to connect the MIDI
Out port of the keyboard to a MIDI In port on your MIDI interface, using a MIDI cable.
For keyboards with tone generators: You should also connect the MIDI Out port of the
MIDI interface to the keyboard MIDI In port. If your MIDI interface offers more than one
MIDI output, connect any other tone generators (or other MIDI devices, such as control
surfaces that require bidirectional MIDI communication) to these.
If your MIDI interface has only one MIDI output: You need to connect the MIDI In of the
second tone generator to the keyboard MIDI Thru port. A third device can be connected
to the MIDI Thru of the second unit, and so on.
The MIDI Thru port replicates the signals coming into the MIDI In port of the device. It’s
better to use a direct connection from the computer MIDI Out port to a device, rather
than chaining too many units, one after the other. Doing so can cause timing problems
in the chain if numerous MIDI commands are sent quickly, due to the slight delays
introduced by each MIDI In to MIDI Thru transaction. As such, a multi input/output MIDI
interface is recommended in studios with several MIDI tone generators and controllers.