How it works
A typical contact sensor has a sensing unit and a magnet fitted to two parts of an opening. Their relative position changes when the door or window moves, allowing the system to report open or closed. Other designs exist, so the exact mounting, permitted gap and orientation must come from the model’s instructions.
Important differences and limits
The reported state describes the sensor’s fitted position. It does not establish that a lock is engaged, that glass is intact or that another opening is closed. An unavailable sensor and a closed sensor are different states. Low battery, poor radio reception or a shifted magnet can produce missing or misleading events.
A useful practical check
Test opening and closing repeatedly before permanent attachment, following the documented mounting limits. Check the event in the controller and any intended notification, not only the sensor indicator. Verify different permitted window positions and inspect alignment after movement or cleaning. Use suitable placement and enclosure requirements for the environment.
An example in practice
For example, a tilted window can leave a contact in a position the installer did not intend. Test the positions people actually use and label the monitored state clearly. If you want a reminder for a window left open, confirm notification delivery and the waiting period; the sensor alone does not create that routine.