WHILE statement in ST

Syntax

WHILE ... DO
  ...
END_WHILE;

Meaning
Use the `WHILE` statement to specify that a group of statements (entered after `DO` up to `END_WHILE`) is to be executed repeatedly until the associated Boolean →expression (entered after `WHILE`) evaluates to value `FALSE` (or an equivalent). If the expression initially evaluates to value `FALSE` (or an equivalent), then the group of statements is not executed at all.

Example

FUNCTION_BLOCK ExampleWhileDocumentation
  VAR
    count, sum, I : INT;
  END_VAR
  
  count := 1;
  sum := 0;
  WHILE LT(count, 11) DO
    sum := ADD(sum, count);
    count := ADD(count, 1);
  END_WHILE;                (* The variable 'sum' equals '55'. *)
END_FUNCTION_BLOCK

No identification of infinite loops

Infinite loops are not identified and prevented by logi.CAD 3. Therefore, enter code in your application to prevent infinite loops (e.g. abort conditions by using IF-statements).