Natural Log (Ln); Relay Ladder; Structured Text; Function Block - Allen-Bradley Logix5000 Reference Manual

Chapter 15 Advanced Math Instructions (LN, LOG, XPY)

Natural Log (LN)

dest := LN(source);
Input Parameter Data Type
EnableIn BOOL
Source REAL
Output Parameter Data Type
EnableOut BOOL
546
The LN instruction takes the natural log of the Source and stores the result in the
Destination.
Operands:

Relay Ladder

Operand
Source
Destination

Structured Text

Use LN as a function. This function computes the natural log of source and stores
the result in dest.
See Structured Text Programming
within structured text.

Function Block

Operand
LN tag

FBD_MATH_ADVANCED Structure

Description
Enable input. If cleared, the instruction does not execute and outputs are not updated.
Default is set.
Input to math instruction.
Valid = any float
Description
The instruction produced a valid result.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Type Format Description
SINT Immediate Find the natural log of this value
INT Tag
DINT
REAL
SINT Tag Tag to store the result
INT
DINT
REAL
for information on the syntax of expressions
Type
FBD_MATH_ADVANCED
Format Description
Structure LN structure