The FR-3X can function as a MIDI controller of other sound modules. To make this connection, the single MIDI port on the FR-3X needs to be set to function as "MIDI out". Here is the procedure:
1) Press and hold the [SET] register to enter the MIDI LIST mode
2) Use treble register 5 and 6 to scroll through the parameters. Stop when the screen says "nld", as this parameter stands for "MIDI Out/In"
3) Use treble registers 1 and 2 to select the setting "Out" (This is achieved when the screen says "out"
4) Press and hold the [SET] register until the display shows: "Urt"
5) Press register 2 to save your settings (the display will say "yes"
6) Press register 7 (enter) to confirm saving this setting