By default, there's one bus, and it has one MIDI In and one MIDI Out.just like a MIDI cable with two DIN connectors. IAC= Inter-Application Communication.or was it connection? Doesn't matter. This driver is like a virtual MIDI cable which you can use to send MIDI to and from applications in OSX. If it's dimmed, double-click it to open its settings and check the 'Device is Online' box to activate it.
Open Audio MIDI Setup (Applications/Utilities) and go to the MIDI tab (or Window if you have Snow Leopard) You'll see and Icon called 'IAC Driver'.
Right now I can think of a way, but it may be 'dangerous' if you are not careful and understand how it works. But I bet you want to have it on while you play/record? I know, I'm a sustain junkie myself.
The easiest would be to enter the sustain data manually after recording in one of Logic's MIDI editors.
