To use Smart Controls with a MIDI controller, you assign hardware controls on the controller (faders, knobs, buttons, drum pads, pedals, and other controls) to screen controls. After you assign a hardware control to a screen control, the screen control receives the MIDI messages from the hardware control.
Those screen controls could be knobs, faders, and switches of any Neural DSP plug-in window.
When Show Advanced Tools is selected in the Advanced preferences pane, you can assign hardware controls to screen controls using the Learn process, which is similar to learning controller assignments for a control surface. Only one screen control can be selected at a time, and each screen control can have only one assignment. When you assign a hardware control, it keeps the assignment for all Logic Pro projects, until you reassign it.
Assign an external hardware control using the Learn button
1. First, tweak the parameter you want to control in the plug-in itself, then press Command+L.
2. Now press the stomp or button; or move the knob or slider on your MIDI controller you want to assign it to.
The command is remembered globally so even when opening other projects, the link between parameter and physical MIDI controller stays.