The Lighting Controller

Do you have any advice on how to transmit a 'program change' to an external device, guitar effects, from
the midi out facility of the buttons. My program is routed through a Behringer X18 desk as an audio card.
Is midi transmitted through USB or do I have to use a midi cable? I would appreciate any advice. Ray

AFAIK your Behringer X18 had no MIDI implementation at all, so, yes you should use some MIDI hardware, an USB to MIDI cable should work