Rockwell Automation FactoryTalk View Machine Edition Users Guide - Manual (Page 479)

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Use expressions
This chapter describes:
 The types of expression components.
 Use the Expression editor.
 Which editors use expressions.
 Format expressions.
 Use tag names and tag placeholders with expressions.
 Use constants.
 Use operators.
 Use math, security, and language functions.
 Use if-then-else logic in expressions.
 The evaluation order of operators.
 Use write expressions.
About expressions
Sometimes the data you gather from devices is meaningful only when you:
 Compare it to other values.
 Combine it with other values.
 Create a cause-effect relationship with other values.
Expressions allow you to create mathematical or logical combinations of data that return
more meaningful values. Depending on the components used in the expression, the value
returned can be in the form of a numeric value, a true/false value, or a text string.
Expressions that result in floating-point values
If an expression results in a floating-point value but an integer value is required, the
floating-point value is rounded.
For information about how values are rounded, see page 7-2.