When a history extension is first added to a component, it is set to be disabled by default. All that is really necessary to enable collection is to change the 'Enable' property to 'true.' Of course, you may desire some other property changes to better configure the collection to suit your actual needs.
Some configuration properties are common among all history extension types. A few properties are unique to the data type or the collection type. Following, is a list of all the properties available.
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Status
read-only field that tells the user the current status.
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Fault Cause
read-only field that displays a reason that the extension is not working.
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Enabled
set either 'true' or 'false' to disable or enable the history extension.
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Active Period
specifies the days of the week as well as start and end times for record collection.
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Active
read - only value that indicates whether or not (true or false) the history collection is active (as defined by the Active Period parameters.
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History Name
is a formatting convention used to provide a way to consistently name histories using a standardized formatting pattern.
The history name format field provides a way to automatically name histories any time a new history is created. The format %parent.name% is the default history name format and this will create a name based on the parent object. Refer to About history names for more details about naming histories.
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History Config
These properties set up the attributes of the History record.
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Id
a unique identification for each history. The id value is the name that was automatically created by the History Name Format or manually created in the name field or rename dialog box.
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Source
a read-only field that displays the ORD of the active history extension.
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Time Zone
a read-only field that displays the time zone of the active history extension.
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Record Type
displays the data that the record holds in terms of: extension type (history) and data type:(BooleanTrendRecord, NumericTrendRecord, and so on).
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Capacity
allows you to set a finite number of records to collect or to choose to collect an unlimited number of records. If you choose the
Record Countoption, an additional “records” field displays. In the “records” field, type in the maximum number of records that you want to save in the history database. -
Full Policy - (Roll or Stop)
allows you to choose what to do when the Capacity number is reached. The
Rolloption drops off the oldest record to make room for the newest record. TheStopoption simply causes the history to stop recording. -
Interval
a read-only field that displays the selected collection type:
regularoninterval. -
System Tags
Available starting in NiagaraAX-3.4, the System Tags property allows you to add an additional identifier (the System Tag) to a history extension. This identifier is then available for selective import or export of histories using the Niagara System History Import or Niagara System History Export option (using the System Tag Patterns). Each System Tag is separated by a semicolon. For example:
NorthAmerica;Region1;Cities. Also see About System Tags. -
valueFacets
allows you to use the Edit Facets dialog box to choose how you want to display the logged data.
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Change Tolerance
for COV based collections, the monitored variable has to change at least this much to be logged as a changed value.
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Interval
for Interval-based collection, the cycle time, or how often the history parameters are checked. Any time you change this parameter, a new history is created (or “split-off”) from the original history because histories with different intervals are not compatible.
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minRolloverValue
this is a number that is used as the starting point for calculations for cumulative logging after a rollover. Rollover occurs after a running total maximum value is reached. Select the
nulloption if a minRolloveValue is unknown. Refer to About delta logging for more details about rollover and delta logging. -
maxRolloverValue
this is a number that is used as a maximum value for calculations when a rollover is detected by the history logging process. Using this parameter and the minRolloverValue parameter helps you avoid getting negative numbers when you are logging running total data, such as energy usage. Refer to About delta logging for more details about rollover and delta logging.
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precision
this option allows you to select 32 bit or 64 bit options for the history data logging. 64 bit allows for higher level of precision but consumes more memory.
