Negate (NEG)

The NEG instruction changes the sign of the Source and places the result in the Destination.

Available Languages
-    Ladder Diagram

-    Function Block

-    Structured Text
This instruction is not available in structured text. *

* There is no equivalent structured text instruction. Use the operator in an expression.
Operands

Operands
-    Ladder Diagram

Operand	Type	Format	Description
Source	SINT INT DINT REAL	Immediate tag	value to negate
Destination	SINT INT DINT REAL	tag	tag to store the result

-    Function Block

Operand	Type	Format	Description
NEG tag	FBD_MATH_ADVANCED	structure	NEG structure

-    Structured Text
Use the minus sign "-" as an operator in an expression. This expression changes the sign of source and stores the result in dest.

dest := -source;

FBD_MATH Structure

Input Parameter	Data Type	Description
EnableIn	BOOL	Enable input. If cleared, the instruction does not execute and outputs are not updated. Default is set.
Source	REAL	Value to negate. Valid = any float

Output Parameter	Data Type	Description
EnableOut	BOOL	Enable output.
Dest	REAL	Result of the math instruction. Arithmetic status flags are set for this output.

Example
Change the sign of value_1 and place the result in negate_result.

-    Ladder Diagram

-    Function Block

-    Structured Text
negate_result := -value_1;

File name: PLC-23_IS_CMI-NEG.pdf
File size: 408.47 KB