How do I map an On/Off knob

I'm trying to make a knob turn on an effect when it is turned to the right and turn off when it is turned all the way back to the left. So far I've gotten close but not all the way there...
Anybody know how to do this?

Ok listening? :p

You need two mappings to do this on the same knob, one for the effect amount and one for on/off

Effect 1 Amount:
Set interaction mode to direct, analog fader/ knob

Effect 1 On:
Set Interaction mode to hold, button

So knob all the way to the left: effect is off. Soon as you turn it, effect is on.

hope that helps.