Storage assembly provided with a robot for placing cassettes, which are filled with wafers, in a carousel, comprising a number of magazines. These magazines lie both above one another and next to one another. In order to be able to determine the correct position of the head of the robot which holds the cassettes with respect to the magazines, it is proposed to provide sensor means which determine the vertical position of the head with respect to the base plate of the magazines and sensor means for determining the horizontal position of the head with respect to the magazines. This horizontal position is determined using openings arranged in the base plate of the magazines. In particular, a main opening and an auxiliary opening are present.