Apple Logic Pro 8 - Manual (Page 92)

92 Chapter 4 Setting Up Your System
If the keyboard can generate its own sounds, 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 bi-directional MIDI communication) to these.
If the MIDI interface connected to your computer only offers 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
is preferable to use a direct connection from the computer MIDI Out 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. This is 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.
Computer
MIDI interface Tone generator
Out port
Out port
Keyboard
In port
In port
In port
Computer
MIDI interface
Out port
Out port
Keyboard
In port
In port
In port
In port
MIDI Thru port
Tone generator 2
Tone generator 3