IF THEN ELSE ELSIF END_IF

Statement - Conditional execution of statements.

Syntax

IF <BOOL expression> THEN
     <statements>
ELSIF <BOOL expression> THEN
     <statements>
ELSE
     <statements> 
END_IF;

Remarks

The IF statement is available in ST only.
The execution of the statements is conditioned by a Boolean expression.
ELSIF and ELSE statements are optional.
There can be several ELSIF statements.

FBD Language Example

Not available.

FFLD Language Example

Not available.

IL Language Example

Not available.

ST Language Example

(* simple condition *)
            
IF bCond THEN
   Q1 := IN1;
   Q2 := TRUE;
END_IF;

(* binary selection *)
IF bCond THEN
   Q1 := IN1;
   Q2 := TRUE;
   ELSE
      Q1 := IN2;
      Q2 := FALSE;
END_IF;

(* enumerated conditions *)
IF bCond1 THEN
   Q1 := IN1;
   ELSIF bCond2 THEN
      Q1 := IN2;
      ELSIF bCond3 THEN
         Q1 := IN3;
         ELSE
            Q1 := IN4;
END_IF;