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Points
Operational purposes, like trend monitoring (in the case of periodic history).
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Collection and analysis by enterprise historians, like PHD servers.
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Because the data from both periodic history and exception history is readily accessible to
specialized historians, the transmission of Experion history data places no additional load on
your control network.
Periodic history
Periodic history collects and stores numerical data at predefined regular intervals. Periodic
history data is generally used for operational purposes such as trend monitoring but is also
collected for historical analysis.
Experion has a comprehensive range of collection rates for periodic history. These collection
rates provide a high degree of flexibility in moderating the load on your control network.
Fast history stores snapshots of a point parameter at short regular intervals. You can
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choose from 8 different collection rates. By default, the fastest collection rate is 5
seconds but this can be changed to 1 second if necessary.
Standard history stores snapshots at slightly longer intervals, ranging from 1 minute to
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30 minutes. The fastest standard history collection rate of 1 minute can be changed to
30 seconds if necessary. In addition to storing snapshots, standard history also
calculates and stores average values, based on the standard history snapshot rates. The
default averages are: 6-minutes, 1-hour, 8-hours, and 24-hours.
Extended history stores 1, 8, and 24-hour snapshots.
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If you need to further customize the periodic history collection intervals, please contact your
Honeywell technical representative.
Note that history collection is synchronized to the system time. For example, the 6-second
collection occurs at 6, 12, 18 (and so on) seconds after the minute boundary on the system.
Exception history
While periodic history is used for numerical data and primarily for operational purposes,
exception history is currently only available for string data collected for analysis by enterprise
historians such as PHD servers.
Like periodic history, exception history scans point parameter values at predefined intervals
and offers a comprehensive range of scanning intervals: with exception history you can
choose from up to 16 different scanning rates. Unlike periodic history, however, exception
history is based on sampling rather than regular collection: it only stores the scanned values
when they are different to the last stored value. This not only helps to minimize the database
size but also the load on the control network.
The default collection rates for exception history are:
Honeywell 2017
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