Device for measuring the position of an object that can be moved forward and backward along a fixed path

The invention relates to a device for measuring the position of an object (1) that can be moved forward and backward along a fixed path, such as a closure element of an open roof construction for a vehicle, comprising a driving unit (4) for said object (1) and a pulse generator (8), which is driven by said driving unit (4), for delivering pulses during the movement of the object (1) along said path. In accordance with the invention a slow potentiometer (13) is used, which potentiometer (13) is likewise driven by the driving unit (4) and which is connected to the driving unit (4) via a transmission (14), such that the potentiometer (13) passes through its range of resistance maximally once during a complete movement of the object (1) along its fixed path. The slow potentiometer (13) provides a monitoring function with respect to the position signal that is based on the number of registered pulses.