Method of testing an optical sensor

A method of testing an optical door sensor of an elevator installation, the optical door sensor having an emitter for emitting a light signal and a receiver for detecting the light signal, the optical door sensor having at least one sensor operating parameter and further having a baseline state in which the receiver can detect a light signal from the emitter, the method comprising:

• setting the optical door sensor in an offset state in which a sensor operating parameter is offset from a baseline setting by an offset amount, the baseline setting corresponding to the baseline state of the optical door sensor;
• conducting a signal test with the optical door sensor in the offset state, the signal test comprising:
• emitting a light signal from the emitter;
• and
• determining whether the light signal is detected by the receiver;
• the signal test having a positive result if the light signal is detected by the receiver and a negative result if the light signal is not detected by the receiver;
• and
• generating an alert when the signal test result is negative for the offset state and the offset amount is less than or equal to a limit margin;
• wherein the sensor operating parameter relates to the intensity of the light signal from the emitter, the sensitivity of the receiver, or the electronic noise intensity in the circuitry of the optical door sensor;
• and wherein the method comprises successively setting the optical door sensor in a plurality of different offset states;
• wherein a signal test is conducted for each of the plurality of offset states until a signal test has a negative result.