Limit (LIM)

The LIM instruction tests whether the Test value is within the range of Low Limit to the High Limit.

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
Low limit	SINT INT DINT REAL	immediate tag	value of lower limit
Test	SINT INT DINT REAL	immediate tag	value to test
High limit	SINT INT DINT REAL	immediate tag	value of upper limit

-    Function Block

Operand	Type	Format	Description
LIM tag	FBD_LIMIT	structure	LIM structure

-    Structured Text
Structured text does not have a LIM instruction, but you can achieve the same results using structured text.

IF LowLimit <= HighLimit AND
 (Test >= LowLimit AND Test <= HighLimit)) OR
 (LowLimit >= HighLimit AND
 (Test <= LowLimit OR Test >= HighLimit)) THEN
<statements>;
END_IF;

FBD_LIMIT 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.
LowLimit	REAL	Value of lower limit. Valid = any float
Test	REAL	Value to test against limits. Valid = any float
HighLimit	REAL	Value of upper limit. 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 LIM instruction.

Examples
Example 1: Low Limit <= High Limit
When 0 <= value >= 100, set light_1. If value < 0 or value > 100, clear light_1.

-    Ladder Diagram

-    Function Block

-    Structured Text
IF (value <= 100 AND (value >= 0 AND value <= 100)) OR
 (value >= 100 AND value <= 0 OR value >= 100)) THEN
  light_1 := 1;
ELSE
  light_1 := 0;
END_IF;


Example 2: Low Limit >= High Limit
When value >= 0 or value <= -100, set light_1. If value < 0 or value > -100, clear light_1.

-    Ladder Diagram

-    Function Block

-    Structured Text
IF (0 <= -100 AND value >= 0 AND value <= -100)) OR
 (0 >= -100 AND (value <= 0 OR value >= -100)) THEN
  light_1 := 1;
ELSE
  light_1 := 0;
END_IF;


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