Rockwell Automation FactoryTalk Historian SE DataLink 4.2 User Guide - Manual (Page 98)

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FactoryTalk Historian DataLink User Guide
90
Data Type Support
Digital (defined states) supported
Int (16 and 32) supported
Float (16, 32 and 64) supported
String (text) supported
Timestamp supported
Blob not supported
FactoryTalk Historian Expressions
FactoryTalk Historian expressions (also known as FactoryTalk Historian
Performance Equations) are used for functions that incorporate
mathematical operations and calculations based on FactoryTalk Historian
points.
For some functions you can substitute a PI Expression for a tag name to
calculate values as they are retrieved from the FactoryTalk Historian
server. Functions that allow an expression argument include both PI Tag
and PI Expression buttons in the function dialog box or task pane.
To base a function on a FactoryTalk Historian calculation expression:
1. Click the PI Expression button at the top of the function dialog box or
task pane.
The Tagname(s) field becomes an Expression(s) field. Other fields
may activate, or become inactive.
2. Type the expression directly in the Expression(s) field, or use the field
to reference a cell containing an expression.
Using field references allow you to specify multiple expressions for a
function. Remember that an expression in a referenced cell is a string,
and should be preceded by an apostrophe.