The NiagaraNetwork’s “History Policies” (History Network Ext) holds an “On Demand Poll Scheduler” that affects imported histories, if set up for “on demand polling”. See Default history policies.
History Policies also functions as the container for “Config Rules” that are used when remote histories are “exported” into the local station. Unlike imported histories, which let you define (and adjust later, if needed) the “capacity” and “full policy” settings in each HistoryImport descriptor, histories that are exported into the station have no associated component—only the history itself. The capacity and “full policy” for each history is set only at creation time, using the local history policies.
You export histories into the station working under a remote station—meaning, from a view of the Histories device extension under the NiagaraStation that represents this (local) station.
See Niagara History Export Manager.
For an example scenario showing histories in two JACE stations that are exported to a Supervisor station, and how history policies apply, see Figure 72.
Additional details are in the following sections:
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Default history policies (including “On Demand Poll Scheduler”)
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config rules (for histories exported into the local station)
The following items are under a NiagaraNetwork’s History Policies:
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On Demand Poll Scheduler
Contains a set of standard poll component parameters which are listed and described in the section Poll Service properties. These parameters affect the operation of the “On Demand” polling for histories so enabled. For related details, see On demand properties in history import descriptors, and the NiagaraAX User Guide section “About On Demand history views”.
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Default Rule
This property has parameters—with wildcard matches to “all” stations and history names, specifying “unlimited” capacity and a “roll” fullPolicy. This means that any history that is exported into the station (from any remote station) is archived using a local history configured with unlimited capacity.
Given the vast storage capacity of a supervisor host PC, the default “one rule” setting may be acceptable on the target of most exported histories (supervisor station). However, if for some reason you are exporting histories to a JACE station, you should definitely change the “Default Rule” of the History Policies under its NiagaraNetwork to specify smaller capacities. Even for a supervisor station, you may wish to change the default rule, and/or add additional optional config rules, as needed.
When a history is exported to the station (from another station), these rules are evaluated to set the local (archived) history’s config properties “capacity” and “fullPolicy.” The first matching rule is used. The “Default Rule” is always at top, and cannot be deleted or renamed.
Rule priority is set by order—as the “Default Rule” is always first, it is highest priority. If you create other rules (in
Workbench, right-click a rule, then click “Duplicate”), you can edit, rename, and reorder as needed.
Each config rule under the network’s History Policies has the following configuration properties:
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Device Pattern
String matching to device names, meaning name of NiagaraStation(s) that are exporting histories. Default value is a wildcard (“*”), meaning all station names are matched.
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History Name Pattern
String matching to history names of histories being exported. Again, default value is a wildcard (“*”), meaning all named histories are matched.
Both device pattern and history name pattern must apply for the rule to be used—otherwise the next rule down (in order) in History Policies is evaluated.
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capacity
The capacity setting to use when creating the local history, if matched by device and history names. Either “unlimited,” or “Record Count,” with a finite record specified.
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fullPolicy
Applies if capacity is not “unlimited,” and specifies if collection continues when the capacity record limit is reached (“roll”) or collection stops (“stop”).
As shown in Figure 72, the Supervisor’s History Policies “config rules” determine the capacity and fullPolicy settings for each history upon export from the JACE stations “WestWing403” and “EastWing403”. Rules are matched to remote station (device) names and history names, which determine the corresponding capacity and full policy values to apply upon history creation. If a history does not match any rule, it is created using the same capacity and full policy as in the source history. For an example related to this scenario, see Example config rules.
As shown in the three-station scenario of Figure 72, histories in two JACE stations are exported to the “Supervisor” station. As shown in Figure 73, the receiving supervisor station has 2 additional config rules under its History Policies of its NiagaraNetwork.
In this example, the highest-priority “Default Rule” matches all (any) stations exporting, with a history name pattern of
“Audit*”—this matches any “AuditHistoryLog”. Capacity is set to unlimited, as all history records are wanted for archive.
The next two rules are applied to histories exported (by any stations), as follows:
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MetersRule — This rule applies to any station, for any history named beginning with “Meter” (“
Meter*”). Any such history is archived using unlimited capacity, as all records are wanted. -
EastWins — This rule applies only to stations named beginning with “East” (“
East*”), for any history. Such a history is archived using a capacity of 100,000 and a “roll” full policy.
Following this example (with exported histories in the JACE stations, as shown in Figure 72), the histories are created in station “Supervisor” as follows:
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WestWing403
Histories are exported using following capacity and fullPolicy (from config rule):
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AuditHistoryLog: unlimited, roll (from Default Rule)
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LogHistory: 500 records, roll (no rule matched, using source history config, as in JACE)
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Meter1: unlimited, roll (from “MetersRule”)
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ZoneTemp1: 500 records, roll (no rule matched, using source history config, as in JACE)
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Meter2: unlimited, roll (from “Meters Rule”)
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ZoneTemp2: 500 records, roll (no rule matched, using source history config, as in JACE)
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EastWing403
Histories are exported using following capacity and fullPolicy (from config rule):
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AuditHistoryLog: unlimited, roll (from “Default Rule”)
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LogHistory: 100,000 records, roll (from “EastWins” rule)
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Meter4: unlimited, roll (from MetersRule)
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ZoneTemp1: 100,000 records, roll (from “EastWins” rule)
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Meter3: unlimited, roll (from Meters Rule)
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ZoneTemp2: 100,000 records, roll (from “EastWins” rule)
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Again, note that the rules are processed in priority order. In this example, if the two optional rules were reordered (“EastWins” above “MeterRule”) before the JACE histories were exported, results would differ. “Meter” histories from EastWing403 would have a 100,000 record capacity instead.