MIDI controllers can have different types of knobs or rotary controllers. Knobs can be either absolute controllers, which send a fixed value determined by the knob’s position or can be relative controllers, which increment or decrement the previous value regardless of their exact position. Knobs can either have a fixed range of movement or be continuous (sometimes called endless rotary encoders).
When you assign a knob screen control using the Assign button, MainStage attempts to determine which type of knob or rotary control on your hardware is sending the MIDI message and sets the value in the Type pop-up menu in the Screen Control Inspector to the correct value. For absolute controllers, the correct value is Absolute; for relative controllers, the correct value can be either Relative (2’s complement) or Relative (Sign magnitude), depending on the type of relative controller. In most cases, there is no need to change the default values unless you intend to use the knob for a specific, non-standard purpose.
When you assign a knob screen control, be sure Absolute is chosen from the Type pop-up menu if the hardware controller is an absolute rotary controller, or one of the Relative values is chosen if the hardware controller is a continuous rotary encoder. Moving the knob through its full range of motion helps ensure that MainStage correctly determines the type of knob you are assigning.