A power control system for an electric cooktop. The power level is set by a knob connected to a potentiometer. Potentiometer information is digitally communicated by a controller over a serial communication bus to a power unit. The power unit communicates power level display information back to the controller over the same serial communication bus. The display information is displayed as numbers on a digital display by the controller. The power unit controls a heating element of the cooktop according to the potentiometer information. A second potentiometer can be added to control a second heating element by operating as a slave to the first controller. Further, multiple heating elements can be controlled by a single potentiometer by dividing the angular rotation into multiple segments or ranges.