n
5, 10, 15, 30, and 60 seconds
n
5, 10, 15, 30, and 60 minutes
n
2, 4, 6, 8, 12, and 24 hours
If you need to customize the exception history collection intervals, please contact your
Honeywell technical representative
Offset groups
If you are collecting standard periodic history or exception history for TPS point parameters
you can control the impact of history collection on the LCN by assigning point parameters to
a history offset group. An offset group is used to specify a predefined delay, which enables
the data collection to be staggered. This helps to reduce the impact of history collection
processes on the performance of the underlying control system. You can choose from 16
default offset groups.
Note that offsets are not reflected in the time stamps for stored data. For example, if there is a
15-second offset and the data is collected at 8:00:15, the data is still time-stamped as if it had
been collected at the beginning of the interval, that is, at 8:00:00.
Storage requirements for history samples
Experion stores history values in physical files. The storage requirements for history
collection are detailed below. However, note that it may not be possible to configure the
maximum number of history parameters available. For more information about the maximum
number of point parameters for which you can collect history, contact your Honeywell
representative.
Periodic history
There are five history files for standard history - one for the snapshots and four for the
averages. There is a single history file for fast history, and there are three history files for
extended history.
Use the following formula to determine your total storage requirements (in bytes) for periodic
(that is, standard, fast, and extended) history:
(((N1+N2+N3+N4+N5+5)*(PS*7+8))+((N6+1)*(PF*7+8))+((N7+N8+N9+3)*
(PE*7+8)))*2
Where:
Variable Description
N1–N5
The number of samples retained by each of the standard history files (N1 = 1-minute
snapshots, N2 = 6-minute averages, and so on).
Points
Honeywell 2017 65
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