The invention relates to a drive for closure elements, in particular in the area of garage and industrial doors, but also for example in the form of roller shutters, with a reference value generator arranged in the motor or in the gearing of the drive for determining the actual position of the closure element. When a reference point position is reached, the reference value generator emits a signal or causes a signal modification, on the basis of which the actual-value generator can be calibrated. According to the invention, the reference value generator has two reference discs rotating in different speeds, which, in predetermined angular positions to one another, define the reference point positions which can be scanned by means of at least one scanning device.