The specifics of this are likely proprietary, but I'm curious if there's a known method to do this.
This product from ESI, https://www.esi-audio.com/products/m4uex/?fbclid=IwAR0_e0jRXIcin4u65ai-kbAK_OHey1Jsy3qipMYsXytYGJKEu3Duxo-QiPM, is able to detect whether a port is connected to a MIDI input or output automatically and switch modes. Does anyone know how this can be achieved?