TRS MIDI Types
Historically Midi used a 5 pin cable, but only 3 of this pins were actually used. It occurred to someone that we can simply use a TRS plug, like the kind that any stereo cable would support, to transmit midi.
Many manufacturers adopted the 3.5mm stereo plug as an option, but three different approaches to mapping the pins emerged:
Diagram from A simplified guide to MIDI over TRS minijacks – minimidi.world]
Type A is the de facto standard, but some manufacturer's still support Type B (notably my Polyend Tracker and my Novation Circuit). My Teenage Engineering EP-133 Supports type A. This makes it a hassle to get all of this gear speaking the same language, but there are adapters available.
You can buy an expensive adapter, or you can make your own with some connectors:
Now just swap the cables, as explained in this video:
