In addition to recipe items, you can include variables in a recipe. A variable is an internal string or numeric value that is never downloaded to the database. For example, you can represent the temperature of your process using a numeric constant, say 50. You can assign this constant to a tagname or, if you prefer, you can assign this value to a variable and then assign the variable to the tagname as the following table shows:
|
Identifier |
Formula |
|
#Temp |
50 |
|
SCADA1:T16F1.F_CV |
#Temp |
While using variables to represent process values is helpful, variables are more powerful when incorporated into a formula. A formula is like a programming assignment statement. It enables you to specify how to represent a value for a recipe item or variable. The chapter Working with Formulas provides more information on using formulas and variables.
