Parenthesis ( )

Operator - Force the evaluation order in a complex expression.

Remarks

Parentheses are used in ST "Structured text" A high-level language that is block structured and syntactically resembles Pascal and IL "Instruction List" This is a low-level language and resembles assembly languages for changing the default evaluation order of various operations within a complex expression.
Example: The default evaluation of 2 * 3 + 4 expression in ST Language gives a result of 10 because * operator has the highest priority.
- Changing the expression as 2 * ( 3 + 4) gives a result of 14.
Parentheses can be nested in a complex expression.

These are the default evaluation priority order for ST language operations:

Priority	Operation	Description
1	- NOT	Unary operators
2	* /	Multiply / Divide
3	+ -	Add / Subtract
4	< > <= >= = <>	Comparisons
5	& AND	Boolean And
6	OR	Boolean Or
7	XOR	Exclusive OR

FBD Language Example

Not available.

FFLD Language Example

Not available.

IL Language Example

In the IL Language:
- The default order is the sequence of instructions.
  - Each new instruction modifies the current result sequentially.
- The opening parenthesis "(" is written between the instruction and its operand.
  - The closing parenthesis ")" must be written alone as an instruction without operand.

Op1: FFLD "Free Form Ladder Diagram"(  IN1
     ADD( IN2
     MUL  IN3
     )
     SUB  IN4
     )
     ST   Q    (* Q is: (IN1 + (IN2 * IN3) -  IN4) *)

ST Language Example

Q := (IN1 + (IN2 / IN 3)) * IN4;