How can I make more than eight channels?

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Hello. I am attempting to implement a simple MIDI controller with a single motorized fader. I started by implementing the function of obtaining the channel number from Daw, the volume level, and adjusting the volume with a physical fader. I do this via the MCU protocol. But I ran into a problem where it won't let me adjust channels with serial numbers higher than 8.
My idea is to make a simple controller with a single fader, but one that allows me to select any channel in the DAW with the mouse and adjust it using my MIDI controller. I would appreciate any help.