Specifications

5-6

5.1 ST

5.1.3 Syntax in ST language

(4) IF ...ELSIF conditional syntax

(a) Format

(b) Description

Syntax 1 is executed when the value of Boolean expression (conditional expression) 1

is TRUE. Syntax 2 is executed when the value of Boolean expression 1 is FALSE and

the value of Boolean expression 2 is TRUE.

Syntax 3 is executed when the value of Boolean expression 1 and 2 are FALSE and the

value of Boolean expression 3 is TRUE.

(5) CASE conditional syntax

(a) Format

(b) Description

The result of the CASE conditional expression is returned as an integer value. The

CASE conditional syntax is used to execute a selection syntax by a single integer value

or an integer value as the result of a complicated expression.

When the syntax that has the integer selection value that matches with the value of

integer expression is executed, and if no integer selection value is matched with the

expression value, the syntax that follows the ELSE syntax is executed.

IF <Boolean expression 1> THEN

<Syntax 1 ...>;

ELSIF <Boolean expression 2> THEN

<Syntax 2 ...>;

ELSIF <Boolean expression 3> THEN

<Syntax 3 ...>;

END_IF;

CASE <Integer expression> OF

<Integer selection 1> : <Syntax 1 ...>;

<Integer selection 2> : <Syntax 2 ...>;

<Integer selection n> : <Syntax n ...>;

ELSE

<Syntax n+1 ...>;

END_CASE;