Rockwell Automation Publication 1756-RM003N-EN-P - October 2011 671
Structured Text Programming Appendix C
Specify a Non-retentive Assignment
The non-retentive assignment is different from the regular assignment described
above in that the tag in a non-retentive assignment is reset to zero each time the
controller does the following:
• Enters the RUN mode.
• Leaves the step of an SFC if you configure the SFC for Automatic reset. (This
applies only if you embed the assignment in the action of the step or use the
action to call a structured text routine via a JSR instruction.)
A non-retentive assignment has this syntax:
tag [:=] expression ;
where:
Component Description
Tag Represents the tag that is getting the new value
The tag must be a BOOL, SINT, INT, DINT, or REAL
[:=] Is the non-retentive assignment symbol
Expression Represents the new value to assign to the tag
If tag is this data type Use this type of expression
BOOL BOOL expression
SINT
INT
DINT
REAL
Numeric expression
; Ends the assignment
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