Sensing device for access point

A method of operating a sensing component for sensing a magnetic field to determine a state of an access point, the access point comprising a first component and a second component that are separable from each other to create an opening to access a premises or part thereof wherein a magnet is mounted on one of the first or second components of the access point, wherein the method comprises:

• operating the sensing component to sense a magnetic field in multiple dimensions to produce a sample representation of the sensed magnetic field, wherein the sample representation is a multi-dimensional representation;
• and
• determining whether the sample representation is in a pre-determined region about a reference representation that is representative of a state of the access point thereby to determine that the sensed magnetic field corresponds to said state of the access point, wherein the pre-determined region comprises a circular cross-section.