In the SIS under Settings > Settings > System settings > local configuration the sensor select mode can be selected. Below the options:
This is the default mode that fits best for most of the installations. In this mode the IR detection determines if the bay is occupied. Only in case of ice/snow on the sensor or when the glasses are dirty the magnetic detection is taking over.
In this mode the magnetic detection determines the status of the sensor.
In this mode the optical detection determines the status of the sensor.
In this mode the bay indicates occupied when both detections detect the vehicle.
In this mode the bay is occupied when one of the technologies are detecting the vehicle.