A light grid 30 - for securing the door edge 13 of a motor-driven door 10 against collision with an object 20, - having a transmitter bar 31 and a receiver bar 36 - having transmitter elements 32 and receiver elements 37, 38, 39 - for detecting an object 20 in the level of the door leaf 12 by interrupting the reception of individual receiver elements, - and having an evaluation means designed - for differentiating a status for the door between a normal case or a security case based on said detection and - determining the security case if a critical number of uninterrupted receiving elements is undershot between the door edge and the object and - determining the normal case if the security case has not been determined, - characterised in that the light grid also has a communication means designed - to output a signal for the status, which is - a LOW signal or a non-frequency-modulated signal or a GND signal in the security case and - a signal modulated with a frequency in the normal case, wherein - the evaluation means is designed - to determine a distance value which corresponds to the number of uninterrupted receiving elements below the door edge up to the first interrupted element, and in that - the communication means is designed - to change the frequency 40 depending on the distance value. - for securing the door edge 13 of a motor-driven door 10 against collision with an object 20, - having a transmitter bar 31 and a receiver bar 36 - having transmitter elements 32 and receiver elements 37, 38, 39 - for detecting an object 20 in the level of the door leaf 12 by interrupting the reception of individual receiver elements, - having transmitter elements 32 and receiver elements 37, 38, 39 - for detecting an object 20 in the level of the door leaf 12 by interrupting the reception of individual receiver elements, - and having an evaluation means designed - for differentiating a status for the door between a normal case or a security case based on said detection and - determining the security case if a critical number of uninterrupted receiving elements is undershot between the door edge and the object and - determining the normal case if the security case has not been determined, - for differentiating a status for the door between a normal case or a security case based on said detection and - determining the security case if a critical number of uninterrupted receiving elements is undershot between the door edge and the object and - determining the normal case if the security case has not been determined, - characterised in that the light grid also has a communication means designed - to output a signal for the status, which is - a LOW signal or a non-frequency-modulated signal or a GND signal in the security case and - a signal modulated with a frequency in the normal case, wherein - a LOW signal or a non-frequency-modulated signal or a GND signal in the security case and - a signal modulated with a frequency in the normal case, wherein - the evaluation means is designed - to determine a distance value which corresponds to the number of uninterrupted receiving elements below the door edge up to the first interrupted element, and in that - to determine a distance value which corresponds to the number of uninterrupted receiving elements below the door edge up to the first interrupted element, and in that - the communication means is designed - to change the frequency 40 depending on the distance value. - to change the frequency 40 depending on the distance value.