A flexible curtain has a ballasting and sealing element and a reinforcing element, and is able to move between an open position and a closed position. The door comprises a detection unit configured to detect an encounter of the ballasting and sealing element with an obstacle. The door also comprises a wireless emitter arranged inside the curtain, close to an upright, in a lateral region of the curtain. The emitter cooperates with the detection unit and emits a radio signal when the obstacle is detected by the detection unit. The radio signal is received by a receiver which cooperates with a driving unit so as to stop or reversely move the curtain.