Hi Nicola
If I understand you, you want a relay bypass. So, after having carefully studied the User Manual
1) set the [BYPASS][BYP TYP] to RLY.
2) Assuming you want to use MIDI Program Change to select the bypass:
edit the [MIDI][RCV MAP] to give you either OFF, ACT,TOG or BYP, depending on how you want to control it. These values are:
OFF Unassigned
BYP BYPass the unit
ACT Make the unit Active, i.e. not bypassed.
TOG Toggle the between bypass and active.