To assign Wah to your expression pedal,

1. Press the 'Edit' button.
2. Turn the main dial until the Wah parameters appear on the screen.
3. Be sure that Wah is turned on by turning the #1 key under the screen.
4. Use the number 2 knob to highlight the Pedal parameter. (just turn the knob once)
5. Press the 'Assign' button.
6. Now rock the pedal back and forth. (The display on the 2120 will show the values changing on the screen)
7. Press 'Store' a few times to save your changes. digitech 2112/2120