Logix5000 Controllers General Instructions - SLAC Confluence

662 Structured Text ProgrammingThe tag retains the assigned value until another assignment changesthe value.The expression can be simple, such as an immediate value or anothertag name, or the expression can be complex and include severaloperators and/or functions. See the next section “Expressions“on page663 for details.Specify a non-retentive assignmentThe non-retentive assignment is different from the regular assignmentdescribed above in that the tag in a non-retentive assignment is resetto zero each time the controller:• enters the RUN mode• leaves the step of an SFC if you configure the SFC for Automaticreset (This applies only if you embed the assignment in theaction of the step or use the action to call a structured textroutine via a JSR instruction.)A non-retentive assignment has this syntax:tag [:=] expression ;where:ComponenttagDescriptionrepresents the tag that is getting the new valuethe tag must be a BOOL, SINT, INT, DINT, or REAL[:=] is the non-retentive assignment symbolexpressionrepresents the new value to assign to the tagIf tag is this data type: Use this type of expression:BOOLBOOL expressionSINTnumeric expressionINTDINTREAL; ends the assignmentPublication 1756-RM003I-EN-P - January 2007