The GRT instruction tests whether Source A is greater 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
GRT tag	FBD_COMPARE	structure	GRT structure

-    Structured Text
Use the greater than signs ">" as an operator within an expression. This expression evaluates whether sourceA is greater 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 GEQ instruction.

Example
If value_1 is greater than value_2, set light_1. If value_1 is less than or equal to value_2, clear light_1.

-    Ladder Diagram

-    Function Block

-    Structured Text
light_1 := (value_1 > value_2);

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The GEQ instruction tests whether Source A is greater than or equal to 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
GEQ tag	FBD_COMPARE	structure	GEQ structure

-    Structured Text
Use adjacent greater than and equal signs ">=" as an operator within an expression. This expression evaluates whether sourceA is greater than or equal to 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 GEQ instruction.

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

-    Ladder Diagram

-    Function Block

-    Structured Text
light_b := (value_1 >= value_2);


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The EQU instruction tests whether Source A is equal to 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 the operator in an expression.

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. REAL values are rarely absolutely equal. If you need to determine the equality of two REAL values, use the LIM instruction. String types are: -          default STRING data type -          any new string type you create To test the characters of a string, enter a string type tag 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
EQU tag	FBD_COMPARE	structure	EQU structure

-    Structured Text
Use the equal sign "=" as an operator within an expression. This expression evaluates whether sourceA is equal to sourceB.

IF sourceA = sourceB THEN
 <statement>;


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 EQU instruction.

Example
If value_1 is equal to value_2, set light_a. If value_1 is not equal to value_2, clear light_a.

-    Ladder Diagram

-    Function Block

-    Structured Text
light_a :=(value_1 = value_2);


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The CMP instruction performs a comparison on the arithmetic operations you specify in the expression.

Available Languages
-    Ladder Diagram





Operands
-    Ladder Diagram

Operand	Type	Format	Description
Expression	SINT INT DINT REAL string	Immediate tag	an expression consisting of tags and/or immediate values separated by operators.

A SINT or INT tag converts to a DINT value by sign-extension.

-    Structured Text
Structured text does not have a CMP instruction, but you can achieve the same results using an IF...THEN construct and expression.

IF BOOL_expression THEN
 <statement>;
END_IF;

Determining the order of operation
The operations you write into the expression are performed by the instruction in a prescribed order, not necessarily the order you write them. You can override the order of operation by grouping terms within parentheses, forcing the instruction to perform an operation within the parentheses ahead of other operations.

Operations of equal order are performed from left to right.

Order	Operation
1	( )
2	ABS, ACS, ASN, ATN, COS, DEG, FRD, LN, LOG, RAD, SIN, SQR, TAN, TOD, TRN
3	**
4	- (negate), NOT
5	*, /, MOD
6	<, <=, >, >=, =, <>
7	- (subtract), +
8	AND
9	XOR
10	OR

Using strings in an expression
To use strings of ASCII characters in an expression, follow these guidelines:

-    An expression lets you compare two string tags.
-    You cannot enter ASCII characters directly into the expression.
-    Only the following operands are permitted:

Operator	Description
=	equal
<	less than
<=	less than or equal
>	greater than
>=	greater than or equal
<>	not equal

Example

If the CMP instruction finds the expression true, the rung-condition-out is set to true.

If you enter an expression without a comparison operator, such as value_1 + value_2, or value_1, the instruction evaluates the expression as:

If the expression is:	The rung-condition-out is set to:
non zero	zero
true	false

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The compare instructions let you compare values by using an expression or a specific compare instruction.

Available Instructions
 

If you want to:	Use this instruction:
compare values based on an expression	CMP
test whether two values are equal	EQU
test whether one value is greater than or equal to a second value	GEQ
test whether one value is greater than a second value	GRT
test whether one value is less than or equal to a second value	LEQ
test whether one value is less than a second value	LES
test whether one value is between two other values	LIM
pass two values through a mask and test whether they are equal	MEQ
test whether one value is not equal to a second value	NEQ

You can compare values of different data types, such as floating point and integer.

The bold data types indicate optimal data types. An instruction executes at its fastest and with it lowest memory requirements if all the parameters of the instruction use the same optimal data type, typically DINT or REAL

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