The manhole cover + smoke monitor is installed on the back of the manhole cover. It measures the current inclination angle of the manhole cover through the acceleration sensor, and monitor for smoke through smoke sensors. The alarm condition is triggered when the manhole cover is tilted and the inclination angle is over 10° (configurable), or when there is smoke. The alarm signal is sent to the monitoring center through wireless transmission.
The device supports setting the regular reporting interval, and alarm angle threshold (default 10°). In the normal condition, the device sends the report message at the regular interval of the periodic report. The status flag in the message can be used to differentiate whether it’s the alarm or normal status. When the device detects that the battery voltage is low, the device reports a low voltage warning message.
The conditions of abnormal movement are: ABS (current angle – initial angle) ＞ alarm angle threshold. When the condition is met, an alarm message is sent.