China Neodymium And Ferrite Magnets Manufacturer & Supplier 
In sensitive environments, reed switches are typically activated using a magnet. A clear understanding of this interaction is crucial to ensure the sensor operates normally. Sensors may be used in normally open, normally closed, or hold modes.
In the normally open mode, when a magnet approaches the reed switch (or vice versa), the reed will close, and when the magnet is removed, the reed will reopen.
In the normally closed mode, when a magnet approaches the reed switch, the reed will open, and when the magnet is removed, the reed will close again.
In terms of the holding mode, the magnetic reed may be in either a normally open or normally closed state. When a magnet approaches the reed switch, the reed will change its state. If the initial state is open, it will now be closed. After the magnet is removed, the reed will remain closed. Only when the magnet with reversed polarity is brought close again will the reed open. After the magnet is removed, the reed will remain open. If the magnet's polarity is reversed again and brought close to the reed switch, the switch will close again, and it will remain closed after the magnet is removed. In this case, it is either a holding mode sensor or a bistable sensor.
The commonly used methods are as follows:
The characteristics of a magnet when it is parallel to and perpendicular to the reed switch are shown in the figure below
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