ENCODER FOR A FLUID DISPENSING SYSTEM AND METHOD OF OPERATING SAME

The present invention relates to an encoder for a fluid dispensing system comprising a magnetic sensor (200) for detecting a rotational angle (ω) of a rotary member (300) around an axis of rotation; a magnet (310) for generating a magnetic field (Ho), the magnet (310) being arranged on the rotary member (300) so that the magnetic poles (312, 314) generate a magnetic field perpendicular to the axis at the magnetic sensor about which the rotary member (300) rotates; wherein the magnetic sensor (200) comprises at least a first and a second magnetic sensing element (210, 220), the first magnetic sensing element (210) configured to generate at least a first output signal, and the second magnetic sensing element (220) configured to generate at least one second output signal, wherein the output signals are indicative of a sensed magnetic field associated at least in part with the magnet, wherein the magnetic sensing elements (210, 220) and the magnet (310) are arranged at predetermined distances from one another centered on the axis of rotation (322); a controller which is configured to compare at least one of the first and second output signals to a first and second predetermined threshold value (limit1, limit2) associated with the predetermined distance, and to calculate field angles of the first signals, to calculate a difference of the field angles, and to compare the difference with a third predetermined threshold value (limits). The controller generates an error signal if a result of at least one of the comparisons to the first and second predetermined threshold values indicates a tamper attempt.