Depending on how you configure your process database, operators may receive alarms for blocks already in alarm. When a block that is in alarm generates another one, the alarm's severity controls how the Alarm Summary object updates.
Handling Multiple Alarms with the Alarm Summary Object
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When subsequent alarms are...
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The Alarm Status is...
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And the alarm value is...
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More severe
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Updated
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Updated.
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Equally or less severe
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Not updated, if the previous alarms for the block are unacknowledged
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Updated.
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The alarm's severity also controls how Data links and animated objects update when they reference the latched alarm. If the current alarm is referenced, Data links and animated objects update according to the new alarm state.
Handling Latched Alarms with Data Links and Animated Objects
When subsequent alarms are...
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Then...
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More severe
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The Data link replaces the old latched alarm with the new one. Animated objects update based on the new latched alarm.
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Equally or less severe
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The Data link retains the old latched alarm until an operator acknowledges it. Animated objects update based on the old latched alarm until an operator acknowledges it.
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For a list of alarms and their severity, refer to the following table.
Block Alarm Severity
Severity
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Alarm Status
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Description
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1 (highest)
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Communications
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Communication Error ("BAD" value).
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2
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Change of State
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Change of State (Digital blocks only).
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3
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Change from Normal
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Change From Normal (Digital block only).
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4
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ERROR
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Error generated by Statistical Data block.
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5
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High High, Low Low
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The block is in the HIHI alarm state (High High), or the block is in the LOLO alarm state (Low Low).
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6
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Rate of Change
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Value exceeds rate of change setting since last scan period.
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7
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High, Low
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The block is in the HI alarm state (High), or the block is in the LO alarm state (Low).
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8
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Deviation
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Deviation from the set point.
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9 (lowest)
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OK
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The block is in normal state.
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Equal Severity
As you can see from the previous table, iFIX treats High and Low alarms, and High High and Low Low alarms with equal severity. As a result, if a Data link showing the latched alarm receives a High alarm and a Low alarm from the same block, the first alarm that iFIX delivers is displayed until an operator acknowledges it. Then the second alarm appears in the link. The Alarm Summary object and objects animated by the latched alarm respond in a similar fashion. The first alarm of equal severity appears or animates the object until an operator acknowledges the alarm.
See Also
