Echelon SmartServer 2.2 - Manual (Page 337)

338 Alarming
Alarm High Limit When the Input Value exceeds the Compare Value by this amount or
more, the Alarm Generator triggers a HIGH_LMT_ALM_2 alarm
condition. This value minus the Hysteresis Alarm High Limit must be
greater than the Warning High Limit.
(Alarm High Limit - Hysteresis Alarm High Limit > Warning High Limit)
Warning High
Limit When the Input Value exceeds the Compare Value by this amount or
more, the Alarm Generator triggers a HIGH_LMT_ALM_1 condition.
This value must be less than the Alarm High Limit minus the Hysteresis
Alarm High Limit, and this value minus the Hysteresis Warning High
Limit must be greater than the Hysteresis Warning Low Limit minus the
Alarm Low Limit.
((Warning High Limit < Alarm High Limit - Hysteresis Alarm High Limit)
&
(Warning High Limit - Hysteresis High Warning Limit > Hysteresis
Warning Low Limit - Warning Low Limit))
Warning Low Limit When the Input Value is below the Compare Value by this amount or
more, the Alarm Generator triggers a LOW_LMT_ALM_1 alarm
condition.
The Hysteresis Alarm Low Limit minus this value must be less than
Warning High Limit minus the Hysteresis Alarm High Limit, and this
value must be less than the Alarm Low Limit minus the Hysteresis Alarm
Low Limit.
((Hysteresis Warning Low Limit - Warning Low Limit < Warning High
Limit - Hysteresis Warning High Limit)
&
(Warning Low Limit < Alarm Low Limit - Hysteresis Warning Alarm
Limit)).
Alarm Low Limit When the Input Value is below the Compare Value by this amount or
more, the Alarm Generator triggers, a LOW_LMT_ALM_2 condition.
This value must be greater than the Warning Low Limit plus the
Hysteresis Alarm Low Limit.
(Alarm Low Limit - Hysteresis Low Alarm Limit > Warning Low Limit)
3. Set hysteresis levels to be associated with the offset limits defined in step 2. When a hysteresis
level is set for an offset limit, the input value must return to the hysteresis level before the alarm
clears and another alarm can be generated based on that limit. This means that the Alarm
Generator will not trigger additional alarms in between the time that the input point reaches an
alarm condition and returns to a normal condition.