Defined Words

The
Trusted®
application supports identifier names called defined words. When building the application, variables and expressions replace the defined words. Possible scopes for defined words include:
  • global scope, available for use in any program organization unit (POU) of a project
  • local scope, available for use in only one POU of a project
Trusted
 programs contain up to 255 defined words.
Trusted
 projects contain a maximum of 3554 defined words.
Defined word names may contain up to 32 characters beginning with a letter or single underscore followed by letters, digits, and single underscores. Names cannot be reserved words, defined words, or data types. Names within a project must be unique. The definition of a defined word cannot contain a defined word.
Examples of Defined Words
lrf_dw
Item
Name
Description
1
Name
Name of the defined word.
2
Equivalent
Equivalent value of the defined word. For POUs, defined words replace literal expressions, boolean expressions, reserved keywords, or complex ST expressions. Defined words that use equivalent complex ST expressions are not supported as inputs for blocks in Ladder Diagram (LD) or Function Blocks Diagram (FBD) POUs.
3
Comment
Free-format text that describes the defined word. Maximum of 60 characters.
When defining such an equivalence, its identifier replaces the attached expression. This Structured Text programming example uses defined words: 
If OK Then

angle := PI / 2.0;

isdone := YES;

End_if;
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