DeltaV software provides an Expression Editor to help you configure the expressions for action statements and transitions that you will use in Sequential Function Charts that make up the logic for command-driven algorithms. The Expression Editor can be accessed from the Properties dialog for either a step action or a transition by clicking the Expression Assistant button.
|
Characters |
Use |
Example |
|---|---|---|
|
/ |
Precedes a reference to an internal parameter (that is, one within the current phase class or module). Use the Insert Internal Parameter button to browse for these parameters. |
'WAIT/ACTIVE.CV' (WAIT is the name of a step in the SFC where the action is created.) |
|
^/ |
Precedes a reference to an internal parameter up one block level. Use the Insert Internal Parameter button to browse for these parameters. |
'^/REQUEST.CV' |
|
// |
Precedes a reference to an external parameter (that is, a parameter within another phase class or module). Use the Insert External Parameter button to browse for these parameters. |
'//XV_102/DC1/SP_D' |
|
# # |
Used to enclose an alias. Use the Insert Alias button to browse for aliases. References to aliases are external because aliases are defined on unit classes, and therefore need to begin with //. Note When you want to reference an Alias IGN (Ignore) field from within an expression, you need to use the syntax /aliasname.IGN (with only one slash and no # signs). |
'//#BLEND_LEV_CV#' |
|
: |
Used to separate a named set from the named set value. |
'vlvnc-sp:OPEN' |
|
:= |
Used to assign values. Step actions use this operator. The value of the right operand is assigned to the left operand. |
'^/REQUEST.CV' := 3202 |
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= |
Used to compare values. Similar operators include >, <, >=, <=, != (not equal to), <> (not equal to). Transitions use these operators. |
'^/REQUEST.CV' = 0 |
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+ |
Used for addition of numeric values or for concatenation of strings. |
'LEV.CV' >= 'INIT_LEV.CV' + '^/FILL_AMT.CV' |
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' ' |
Single quotes are used to enclose parameters. |
|
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" " |
Double quotes are used to enclose strings. |
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; |
Used to end action statements. |
