You’re a bit vague - is your friend using Renoise + Duplex?
Generally speaking (true for any DAW), the ability to update the controller from the DAW is called bi-directional, or full duplex communication.
Without this you could tell the DAW to do something by using the controller, but the DAW wouldn’t know how to tell the controller to display stuff.
Renoise doesn’t have bi-directional MIDI or OSC communication built-in, which is why Duplex was invented in the first place. And one of it’s strengths is that you don’t have to “wonder” how any given controller integrates with Renoise, as you can install the Duplex tool and then play with the virtual control surface (a full-featured on-screen representation of your chosen controller).
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In other news, I’ve made an Effect config for all the nanoKontrol2 users
Here’s a picture explaining the layout (grayed-out stuff is unassigned):
4826
Copy this to Duplex/Controllers/nanoKONTROL2/Configurations/ and restart…
4827 Effect.lua