Conditional Expression

The form of a conditional expression is as follows:

{Condition} ? [expression1] : [expression2]

Where:

Condition is:

• an object that acquires a value of Boolean type
• a logical expression enclosed in any type of brackets - { }, ( ) or [ ]

If the value of the condition is TRUE, then expression1 is evaluated. Otherwise, expression2 is evaluated.

Expression1 and Expression2 is:

• arithmetical expression enclosed in any brackets - - { }, ( ) or [ ]

The result value of an expression that is evaluated is the result of the conditional expression. Just the expression, for which the Condition is met, is evaluated.

Warning:
If a function, that uses its previous internal state (e.g. %PrevV, %Integral,...) for evaluation, is included in the expression that has not been evaluated, the internal state is not correct!

Example of conditional expression

The task is to indicate the state when the water level (the object Water_level) in the cistern falls under the minimum (the object Minimum).

We define a new eval tag called Low_level of logical type, which value is determined by the expression:

{Water_level < Minimum} ? [@TRUE] : [@FALSE]

If the arithmetical expression {Water_level < Minimum} is true, then the value of the object Low_level is TRUE, otherwise, the value is FALSE. The object Low_level is to be evaluated if a change of the input objects occurs (i.e. when Water_level or Minimum has changed).