Rockwell Automation 1756-HIST2G Historian ME 2.1 - Manual (Page 274)

F ACTORY T ALK H ISTORIAN ME M ODULE U SER G UIDE
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
Compression Min Hr and Compression Max Hr is between 0 and 23.

Compression Min Min and Compression Max Min is between 0 and 59.

Compression Min Sec and Compression Max Sec is between 0 and 59.
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 it connection
to the FactoryTalk Historian ME or if a running tag is removed from the controller
but not from the FactoryTalk Historian ME. Poor quality data displays in red in the
point list.