I helped my keyboard player get this working with his Korg Kronos and BandHelper on an Android tablet just a few weeks ago.
* We opted to have BandHelper control the Kronos (so that selecting songs in BandHelper would change the sounds on the Kronos)
* He is using a Bluetooth page turn pedal to move to next song/previous song in BandHelper, and has configured his layout in BandHelper to send MIDI upon song selection
* We used a USB OTG adapter to connect the tablet to the Kronos (and we used a Y-type cable so that we could power the tablet simultaneously). For my iPad, I was able to connect to the Kronos using an Apple USB to Lightning Camera Connection adapter.
Here's what I recall about our setup:
- Created a new MIDI device in Bandhelper with Port = All, Channel = Channel 1 (or the MIDI channel on which your Kronos is configured to communicate), Numbering = 0-127
- On his Android device (which should only be necessary on a device running Android 6 or greater), we had to turn off Help -> Utilities -> Use Old MIDI Framework before the two devices would communicate.
- Once we had the devices talking to one another (as made evident by seeing activity in the MIDI monitor log in BandHelper...which you can access by tapping the MIDI button in the upper tool bar of the app), we set up MIDI presets for each song with Program Change values of 0, X, Y where X = the Kronos set list number and Y = the Kronos song number. It took some testing to determine the proper values, but we used that MIDI monitor log in BandHelper to see what values are being sent out by the Kronos when we selected a song in a particular set list and could extrapolate the remaining values from there.
- Attached the MIDI presets to their corresponding songs in BandHelper (Repertoire -> Songs, select the song, tap +Add MIDI Preset, select the preset)
If you have a limited number of patches that you use repeatedly for various songs, another way to do this would be to instead create one MIDI preset for each patch and then just attach the same preset to multiple songs in BandHelper. Or if you use multiple patches on a single song, you can attach more than one MIDI preset to that song and add the "Multiple MIDI Buttons" item to your layout to see a list of the MIDI presets attached to each song while viewing a set list with that layout.