On Demand Poll Scheduler that affects imported histories, if set up for on-demand polling. 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 History Import 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.
The On Demand Poll Scheduler contains a set of standard poll component properties as described in the Drivers Guide. These properties affect the operation of the on-Demand polling for histories so enabled.
Default Rule contains a set of properties with wildcard matches to all stations and history names, specifying “unlimited” capacity and a “roll” fullPolicy. So that any history that is exported into the station (from a remote station) is archived using a local history configured with unlimited capacity.
Given the vast storage capacity of a
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.