Less Than (LES)

The LES instruction tests whether Source A is less than Source B.

Available Languages
-    Ladder Diagram

-    Function Block

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

* There is no equivalent structured text instruction. Use other structured text programming to achieve the same result.

Operands
-    Ladder Diagram

Operand	Type	Format	Description	Notes
Source A	SINT INT DINT REAL String type	Immediate tag	value to test against Source B	If you enter a SINT or INT tag, the value converts to a DINT value by sign-extension. String types are: -          default STRING data type -          any new string type you create To test the characters of a string, enter a string type for both Source A and Source B.
Source B	SINT INT DINT REAL String type	Immediate tag	value to test against Source A

-    Function Block

Operand	Type	Format	Description
LES tag	FBD_COMPARE	structure	LES structure

-    Structured Text
Use the less than sign "<" as an operator within an expression. This expression evaluates whether sourceA is less than sourceB.

IF sourceA < sourceB THEN
 <statements>;

FBD_COMPARE 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.
SourceA	REAL	Value to test against SourceB Valid = any float
SourceB	REAL	Value to test against SourceA Valid = any float

Output Parameter	Data Type	Description
EnableOut	BOOL	Enable output.
Dest	BOOL	Result of the instruction. This is equivalent to rung-condition-out of the ladder diagram LES instruction.

Example
If value_1 is less than value_2, set light_3. If value_1 is greater than or equal to value_2, clear light_3.

-    Ladder Diagram

-    Function Block

-    Structured Text
light_3 := (value_1 < value_2);


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