28X16D1H – User Manual3-2.3 SensorThe Sensor (Alarm) feature allows the user to setup alerts based upon the DVR’salarm sensors being triggered:Sensor DescriptionItem DescriptionEnable Enable/Disable sensorPolarityWhen the sensor has been triggered, the sensor alert will beactivated (i.e. NC; Normally Closed)When the sensor has been triggered, the sensor alert will bede-activated (i.e. NO; Normally Open)3-2.4 SystemWhen a system event occurs the user can be notified by means of email or a relay signal beingsent (which can be configured within Receiver Setup). If the buzzer option is enabled, an errorsuch as a hard drive writing failure, will cause the onboard buzzer to sound continuously.