X Air - How to send MIDI data from Logic Pro - YouTube
OsiMIDI
Mr_hollywood - The latest NanoMute version 3 firmware (for the DIY XR18 Midi footswitch) is now available and adds Mute Groups, DCA mutes, A/B Snapshots, Screen blanking options, and introduces FX tap
Behringer X Air XR18 – Musikhaus Thomann
XR-18 controlled from GP4 - Shared rackspaces - Gig Performer Community