Natural Log (LN)

The LN instruction takes the natural log of the Source and stores the result in the Destination. The Source must be greater than zero or a minor fault will occur.
Available Languages
Ladder Diagram
Ladder_LN
Operands
TIP: Unexpected operation may occur if:
  • Output tag operands are overwritten.
  • Members of a structure operand are overwritten.
  • Except when specified, structure operands are shared by multiple instructions.
There are data conversion rules for mixing numeric data types within an instruction. See Data conversions.
Ladder Diagram
Operand
Data Type
Format
Description
Source
SINT
INT
DINT
LINT
USINT
UINT
UDINT
ULINT
REAL
LREAL
Immediate
tag
Find the natural log of this value.
Destination
SINT
INT
DINT
LINT
USINT
UINT
UDINT
ULINT
REAL
LREAL
tag
Tag to store the result of the instruction.
Affects Math Status Flags
Major/Minor Faults
None specific to this instruction. 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
Set Rung-condition-out to Rung-condition-in.
Dest = value of natural log of the Source.
Postscan
N/A
Examples
Ladder Diagram
FTStudio LN EX V1
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