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Rate, in seconds, at which subscription callbacks occur


UpdateRate specifies the rate, in seconds, at which subscription callbacks occur. Therefore, UpdateRate determines how often the cached data can be updated and how often data change events can occur. Consequently, UpdateRate also controls the rate at which data is logged. You start logging data change events with the start function.

Data change events can occur only for active items in an active group. Additionally, subscription must be enabled for the group.

Note that servers can select an update rate that differs from the requested value. If this occurs, UpdateRate is automatically updated with the returned value. By specifying an update rate of 0, updates will occur as soon as new information becomes available for the daitem object. New information is considered to be a change in the Quality property or a change in the data Value that exceeds the DeadbandPercent property value.



Read-only while logging

Applies to


Data type



Any value greater than or equal to 0. The default value is 0.5.

See Also