Types of Structured Text Statement
You can build structured text code using these statement types:
Statement Type	Examples
Assignment Statement	Assigns a value to a variable. For example:
	Running := TRUE;
	Setpoints[0] := 12.5;
	Setpoints[1] := Setpoints[0] + 2.5;
Function Call Statement	Call a function discarding the return value. For example:
	StartPump();
	IncreaseTargetSetpoint( Increment:=5.5 );
IF Statement	Choose different statements to run depending on a condition. For example:
	IF Level < 2.5 THEN
	State := 'Normal';
	ELSE
	State := 'High';
	END_IF;
CASE Statement	Run a block of statements based on a selector value. For example:
	CASE PumpState OF
	0:00
	StateDescription := "Stopped";
	1:00
	StateDescription := "Running";
	2:00
	StateDescription := "Failed";
	ELSE
	StateDescription := "Invalid";
	END_CASE;
FOR Statement	Run statements a defined number of times. For example:
	Sum := 0;
	FOR Index:=0 TO 3 DO
	Sum := Sum + Values[ Index ];
	END_FOR;
FOR EACH Statement	Run statements for each item in a collection. For example:
	FOR EACH Item IN Collection DO
	...
	END_FOR;
WHILE Statement	Run statements while a condition is true. For example:
	Index := 0;
	Sum := 0;
	WHILE Index < 10 DO
	Sum := Sum + Values[ Index ];
	Index := Index + 1;
	END_WHILE;
REPEAT Statement	Run statements until a condition is true. For example:
	Index := 0;
	Sum := 0;
	REPEAT
	Sum := Sum + Values[ Index ];
	Index := Index + 1;
	UNTIL Index >= 10 END_REPEAT;
EXIT Statement	Exit a loop statement early. For example:
	FOR Idx:=0 TO 9 DO
	IF Flags[ Idx ] THEN
	EXIT;
	END_IF;
	END_FOR;
RETURN Statement	Return from a Program Unit early. For example:
	IF ProcessedFinished THEN
	RETURN;
	END_IF;