The SDE-3000EVH and SDE-3000D use 3.5mm TRS MIDI Type A jacks. Note that MIDI Type A and Type B are not compatible. Verify the type before purchasing third-party cables.
For BOSS-branded cable options, use a TRS/MIDI connecting cable (BMIDI-5-35, BMIDI-1-35, or BMIDI-2-35) or a TRS/TRS connecting cable (BCC-1-3535 or BCC-2-3535), sold separately.