Rockwell Automation 1756-HIST2G FactoryTalk Historian ME 2.2 - Manual (Page 286)

F ACTORY T ALK H ISTORIAN ME M ODULE U SER G UIDE
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Data Collection
This section contains Data Collection service considerations.
Scan Types
Observe the following scan type recommendations:
„
Polled tags are for Data Collection are intended for scan rates greater than 0.5
seconds.
„
Advised tags are for Data Collection are intended for scan rates greater than 0.5
seconds.
„
High Speed tags are for Data Collection are intended for scan rates as fast as 10
ms.
High Speed Trend Pace Error
If the message “[ERROR] Unable to keep pace with High Speed Trend causing data
loss” message is logged in the System Log page, potential data loss may occur. Due
to performance issues with the controller, the backplane, or the module, the module
cannot receive new high-speed events from the controller. Stop and start Data
Collection to mitigate the impact.
Data Types
The int64 (LINT) data type is not supported at this time.
Data Quality
FactoryTalk Historian ME tracks data quality during Data Collection and Data
Transfer. For example, poor quality data can occur if the controller loses its
connection to the FactoryTalk Historian ME or if a running tag is removed from the
controller but not from FactoryTalk Historian ME. Bad quality data displays in red in
the point list.
Data Transfer
This section describes Data Transfer service considerations.
„
FactoryTalk Historian ME only supports Data Transfer to a single FactoryTalk
Historian SE or PI server. Collectives are not supported. If data is required in