Allen-Bradley Logix5000 Reference Manual

Rockwell Automation Publication 1756-RM003N-EN-P - October 2011 549
Advanced Math Instructions (LN, LOG, XPY) Chapter 15
Log Base 10 (LOG)
The LOG instruction takes the log base 10 of the Source and stores the result in
the Destination.
Operands:
Relay Ladder
Structured Text
Use LOG as a function. This function computes the log of source and stores the
result in dest.
See Structured Text Programming
for information on the syntax of expressions
within structured text.
Function Block
FBD_MATH_ADVANCED Structure
Operand Type Format Description
Source SINT
INT
DINT
REAL
Immediate
Tag
Find the log of this value
Destination SINT
INT
DINT
REAL
Tag Tag to store the result
Operand Type Format Description
LOG tag FBD_MATH_ADVANCED Structure LOG structure
dest := LOG(source);
Input Parameter Data Type Description
EnableIn BOOL Enable input. If cleared, the instruction does not execute and outputs are not updated.
Default is set.
Source REAL Input to math instruction.
Valid = any float
Output Parameter Data Type Description
EnableOut BOOL The instruction produced a valid result.
Dest REAL Result of the math instruction. Arithmetic status flags are set for this output.

Allen-Bradley Logix5000 Specifications

General

Brand	Allen-Bradley
Model	Logix5000
Category	Controller
Language	English