I used midi mapping in H9 to send midi PC to Line 6 M5 and it was only possible to assign from the menu inside the pedal not in H9 Control app in 2015. It's 2018 now, anything changed? Is it possible to assign midi out mappings from H9 Control app?
Currently, you still need to assign midi out mappings on the pedal. You can go to the setting menu by pressing and hold the HOTKNOB and right footswitch, and then scroll to "MIDI" and "XMT CC".