In Command mode the handle position sets the maximum output voltage when the channel is turned on full by rotating the knob on the Cab2. After the Cab2 turns on the channel the handle can be used to vary the output voltage but in my opinion it is much more convenient to just use the Cab 2 to control the track voltage. In Command mode the handle has no effect if the channel is not activated with the Cab2 (or an iPhone using the iCab app.)