A near-far security sensor for monitoring a barrier, comprising: a first sub-sensor for detecting a magnetic field produced by a magnet ; a second sub-sensor for detecting the magnetic field, wherein the first sub-sensor comprises a first magnetic field sensitivity and the second sub-sensor comprises a second magnetic field sensitivity, wherein the second magnetic field sensitivity is at least five times more sensitive than the first magnetic field sensitivity; a memory for storing processor-executable instructions; and a processor coupled to the first sub-sensor, the second sub-sensor and the memory for executing the processor-executable instructions that cause the near-far sensor to: select one of the sub-sensors to monitor during a normal operating mode; monitor the selected sub-sensor during the normal operating mode; determine whether the barrier has been opened based on either the first sub-sensor or the second sub-sensor, depending on which sub-sensor was selected; wherein the processor-executable instructions further comprise instructions that cause the near-far sensor to periodically monitor the sub-sensor that was not selected, determine a reading from the selected sub-sensor at first predetermined time intervals; determine a second reading from the non-selected sub-sensor at predetermined second time intervals, wherein the predetermined second time intervals are greater than the first predetermined time intervals, and determine that an abnormal condition is present when the selected sub-sensor does not indicate that the barrier has been opened and the sub-sensor that was not selected determines the presence of a second magnetic field produced by a second magnet. a first sub-sensor for detecting a magnetic field produced by a magnet ; a second sub-sensor for detecting the magnetic field, wherein the first sub-sensor comprises a first magnetic field sensitivity and the second sub-sensor comprises a second magnetic field sensitivity, wherein the second magnetic field sensitivity is at least five times more sensitive than the first magnetic field sensitivity; a memory for storing processor-executable instructions; and a processor coupled to the first sub-sensor, the second sub-sensor and the memory for executing the processor-executable instructions that cause the near-far sensor to: select one of the sub-sensors to monitor during a normal operating mode; monitor the selected sub-sensor during the normal operating mode; determine whether the barrier has been opened based on either the first sub-sensor or the second sub-sensor, depending on which sub-sensor was selected; wherein the processor-executable instructions further comprise instructions that cause the near-far sensor to periodically monitor the sub-sensor that was not selected, select one of the sub-sensors to monitor during a normal operating mode; monitor the selected sub-sensor during the normal operating mode; determine whether the barrier has been opened based on either the first sub-sensor or the second sub-sensor, depending on which sub-sensor was selected; wherein the processor-executable instructions further comprise instructions that cause the near-far sensor to periodically monitor the sub-sensor that was not selected, determine a reading from the selected sub-sensor at first predetermined time intervals; determine a second reading from the non-selected sub-sensor at predetermined second time intervals, wherein the predetermined second time intervals are greater than the first predetermined time intervals, and determine that an abnormal condition is present when the selected sub-sensor does not indicate that the barrier has been opened and the sub-sensor that was not selected determines the presence of a second magnetic field produced by a second magnet. <EOS>