An Enteral Feeding Pump Motor Unit and Method of Use are disclosed. The motor unit uses optical sensors to monitor the rotational period and position of a platen of the motor unit. If the rotational period is different from a predetermined desired period, a controller in communication with the optical sensors and the platen changes the rate at which the platen rotates so as to effectuate movement of a desired amount of fluid through a delivery set passing through the motor unit. In accordance with one aspect of the invention, the optical sensors are disposed in an asymmetrical pattern to enable self-testing and to avoid ambiguous readings.