Log Base 10 (Log); Relay Ladder; Structured Text; Function Block - Allen-Bradley Logix5000 Reference Manual

Log Base 10 (LOG)

dest := LOG(source);
Input Parameter Data Type
EnableIn BOOL
Source REAL
Output Parameter Data Type
EnableOut BOOL
Dest REAL
The LOG instruction takes the log base 10 of the Source and stores the result in
the Destination.
Operands:

Relay Ladder

Operand
Source
Destination

Structured Text

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

Function Block

Operand
LOG 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.
Result of the math instruction. Arithmetic status flags are set for this output.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Advanced Math Instructions (LN, LOG, XPY)
Type Format Description
SINT Immediate Find the 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 LOG structure
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