Less Than (LT)
When enabled, the LT instruction and the operator 
tests Source A is less than Source B.
tests Source A is less than Source B.Available Languages
Ladder Diagram
Operands
There are data conversion rules for mixing numeric data types within an instruction. See Data conversions.
Ladder Diagram
Numeric Comparison
Operand | Data Type | Format | Description |
|---|---|---|---|
Source A | SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL | immediate tag | Value to test against Source B |
Source B | SINT INT DINT LINT USINT UINT UDINT ULINT REAL LREAL | immediate tag | Value to test against Source A |
String Comparison
Operand | Data Type | Format | Description |
|---|---|---|---|
Source A | String type | immediate literal value tag | String to test against Source B |
Source B | String type | immediate literal value tag | String to test against Source A |
Affects Math Status Flags
No
Major/Minor Faults
See
LT String Compare Flow Chart
for faults.See Index through arrays for array-indexing faults.
Execution
Ladder Diagram
Condition/State | Action Taken |
|---|---|
Prescan | N/A |
Rung-condition-in is false | Set Rung-condition-out to Rung-condition-in |
Rung-condition-in is true | Numeric compare: If Source A and Source B are not NANs and Source A is less than Source B. Set Rung-condition-out to true else Clear Rung-condition-out to false. |
String compare: See LT String Compare Flow Chart. If output is false Clear Rung-condition-out to false else Set Rung-condition-out to true | |
Postscan | N/A |
LT String Compare Flow Chart
Example
Ladder Diagram
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