Drive operator for a movable barrier such as a roller shutter, awnings or gates, adapted to move the barrier by a motor between two end-stop positions defined by antagonist mechanical constraints, comprising - means for digitalizing through sampling a physical quantity related to the motor into an electrical signal; - means for acquiring said signal by measuring it indirectly through measure of the current absorption of the motor, or the voltage across its windings and/or the current phase-shift of the same, said signal representing the torque outputted by the motor, the resistant torque, or the difference between the two, or a rotary encoder for the acquisition of said signal, said signal representing the position of the motor shaft; - a microprocessor adapted to (i) monitor, through the means for acquiring, at the two end-stop positions said electrical signal whose time course during the impact of the mechanical constraints varies in a substantially repeatable manner, the time courses of said signal relative to one of the two end-stop position and the other end-stop position being different; (ii) obtain at least one value which expresses the difference between the time course of said signal relative to one of the two end-stop position and the other end-stop position; (iii) discriminate the two end-stop positions on the basis of said value, wherein said value is calculated as the integral of the signal or as a weighted or non-weighted sum of samples of the same signal. - means for digitalizing through sampling a physical quantity related to the motor into an electrical signal; - means for acquiring said signal by measuring it indirectly through measure of the current absorption of the motor, or the voltage across its windings and/or the current phase-shift of the same, said signal representing the torque outputted by the motor, the resistant torque, or the difference between the two, or a rotary encoder for the acquisition of said signal, said signal representing the position of the motor shaft; - a microprocessor adapted to (i) monitor, through the means for acquiring, at the two end-stop positions said electrical signal whose time course during the impact of the mechanical constraints varies in a substantially repeatable manner, the time courses of said signal relative to one of the two end-stop position and the other end-stop position being different; (ii) obtain at least one value which expresses the difference between the time course of said signal relative to one of the two end-stop position and the other end-stop position; (iii) discriminate the two end-stop positions on the basis of said value, wherein said value is calculated as the integral of the signal or as a weighted or non-weighted sum of samples of the same signal. (i) monitor, through the means for acquiring, at the two end-stop positions said electrical signal whose time course during the impact of the mechanical constraints varies in a substantially repeatable manner, the time courses of said signal relative to one of the two end-stop position and the other end-stop position being different; (ii) obtain at least one value which expresses the difference between the time course of said signal relative to one of the two end-stop position and the other end-stop position; (iii) discriminate the two end-stop positions on the basis of said value, wherein said value is calculated as the integral of the signal or as a weighted or non-weighted sum of samples of the same signal.