WHAT DOES IT MEAN?
A photocell is an optical sensing device that can detect an interruption of a beam across a monitored point near a powered garage door.
In practice
A compatible controller uses the signal as part of the door's protective response. Position and system design determine what is detected. A single beam does not monitor the whole opening in the same way as a multi-beam light curtain.
Keep the area around sensors clear and follow the manufacturer's cleaning and inspection instructions. Dirt, alignment problems or damage can cause faults. Do not bridge wiring or disable the sensor to restore operation; have a competent specialist assess the complete system.
