ST Instruction ‘CASE’

Use this dialog box for pooling several conditional instructions containing the same condition variable into a construct.

Syntax:

CASE <Var1> OF
<value1>:<instruction1>
<value2>:<instruction2>
<value3, value4, value5>:<instruction3>
<value6 ... value10>:<instruction4>
...
<value n>:<instruction n>

{ELSE <ELSE-instruction>}

END_CASE;

The section within the curly brackets {} is optional.

Processing scheme of a CASE instruction.

• If the value of the variable <Var1> is <value i>, then the instruction <instruction i> is executed.
• If the variable <Var1> has non of the given values, then the <ELSE-instruction> is executed.
• If the same instruction is executed for several values of the variable, then you can write the values in sequence, seperated by commas.

Example

CASE iVar OF
1, 5: bVar1 := TRUE;
      bVar3 := FALSE;

2: bVar2 := FALSE;
   bVar3 := TRUE;

10..20: bVar1 := TRUE;
        bVar3= TRUE;
ELSE
   bVar1 := NOT bVar1;
   bVar2 := bVar1 OR bVar2;
END_CASE;