Choosing Zero from the Experiment menu sets the current reading of a sensor to zero. The calibration is not otherwise changed. For example, a Force Sensor will have different readings depending its orientation. In this case, you want the sensor to read zero in the orientation of use before applying an external force to the sensor.
There are three ways to zero a sensor:
If more than one sensor is attached, a dialog for choosing the sensor(s) you want zeroed appears.
Some sensors should almost always be zeroed. For this reason, when the following sensors are used, the Zero button will be automatically placed on the Toolbar:
The following sensors cannot be zeroed: