MIDI Port Routing is REALLY EASY!
MIDI Port Routing is just that: routing or re-routing the destination of MIDI going through your iConnectivity interface.
The screen shots here show the iConnectMIDI4+, which has the most MIDI ports available, but it works exactly the same way with all our rack-height audio + MIDI interfaces.
Port (left column): MIDI enters the interface from a 16-channel MIDI Port. This can be a MIDI device - USB or 5-pin - or the output ports from a computer device (Mac/PC/iOS).
In the pic below we have a Mac running Logic Pro X connected to USB Device Jack 1; the pop-up in Logic shows all the available MIDI ports a track can be assigned to.
Destination (the matrix on the right): MIDI headed to the Source is routed/re-routed wherever you assign it. This can be multiple destinations, none, or you could even route it back to the same Port (if you wanted to take advantage of the built-in MIDI Port Filters, Channel Remapping, Controller Filtering, and Controller Remapping).
In the example below we have a Mac running Logic Pro X in USB Device Jack 1, and a Mac running Pro Tools in USB Device Jack 2.
A MIDI track in Logic is assigned to DIN 1, and it's also going to Pro Tools Port 1 (that's an internal 16-channel MIDI Port). This happens to be handy, because Logic tracks can't have multiple destinations.