Thanks for clarifying.
The H90 can only output MIDI on one channel. If you have the H90’s MIDI channel set to 5, it will output MIDI messages on channel 5.
The H90 will only transmit MIDI from the DIN output, so you would need to connect the DIN output to your iPad setup somehow (it’s not clear how your MIDI is routed).
I think this is possible if you configure your settings in a certain way, but why not just connect a MIDI controller directly to the iPad to turn the pages? Routing the switch through the H90 into the iPad makes the setup more complicated, and it sounds like the iPad is already acting as the “MIDI brain” of your setup.
