AN35: Poseidon – Preventing false alarms
Poseidon monitoring unit sends SMS, e-mail, and SNMP traps whenever a sensor value is outside of a safe range. However, when the temperature or humidity fluctuates, the unit can send tens or hundreds of messages that are unnecessary and bother the user. AN35 describes ways of avoiding false alarms.
Sources of false alarms
The problem is particularly bothering if you use Poseidon with a GSM modem that sends a text message (SMS) to your mobile phone upon each and every alarm.
Poseidon supports two functions to avoid false alarms:
Alarm Notification Delay
The Alarm Notification Delay function prevents an alarm alert from being sent if the alarm lasts only for a very short time. The same delay is applied to alarm activation and alarm deactivation alerts.
Hysteresis / Idle range
The Hysteresis setting defines a tolerance band for suppressing alarm alerts. The function prevents multiple alarm alerts if the reading oscillates around the specified threshold. The range is configured independently for each sensor.
The Alarm Notification Delay function is supported in the following (and newer) firmware versions. Firmware files are available here: Poseidon model XXXX
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