The BOSS EV-1-WL can be used to control specific external MIDI capable devices parameters in realtime.
Important note: CC#'s 32-63 and 96-127 are not available CC#'s since these CC#'s fall under the plug- and-play device requirements for a USB plug-and-play remote controller.
The MIDI Channels and settings on your external device and the EV-1WL need to be matched. Also, be sure that the CC#'s in your external MIDI device match the CC#'s sent from EV-1-WL and that the MIDI receive settings are ON in your external MIDI device.
EXP (OFF) is sending expression CC when the second LED is OFF.
EXP (ON) is sending expression CC when the second LED is ON.
EXP SW will also send MIDI CC on and off. The same is for CTL input 1,2.
You'll also want to confirm that the CC#'s and specific controls in the external MIDI device are matching those in EV-1-WL.