In the case of bohan's comment how did you get it to trigger bank switches?

If you step into H9's system settings and turn on program transmit[PGM.XMT], and connect the MIDI OUT of H9 to GR33's MIDI IN. By default, Switching presets on H9 will also change the preset/bank on GR33 (preset 1 – 99). If that doesn't work, you may need to look at GR33's system settings or its manual for further information.

You can also connect GR33's MIDI OUT to H9's MIDI IN to use GR33 as a master to change presets on H9. There are many other functions available. By using H9 Control, you can more easily assign H9's MIDI CC/PC receive functions.