Logic Guide - LOG (Built-in Functions, Function Blocks, and Conversions)

LOG

Function Name	LOG
Description	Converts a REAL or LREAL input into a base 10 logarithm value that is the output. The base 10 logarithm is also a REAL or LREAL.
Arguments	Input 1 {REAL or LREAL}. For more information on the data types for the inputs and outputs, see Data Type Hierarchy.
Returns	Output {REAL or LREAL}

Function Name

LOG

Description

Converts a REAL or LREAL input into a base 10 logarithm value that is the output. The base 10 logarithm is also a REAL or LREAL.

Arguments

Input 1 {REAL or LREAL}.

For more information on the data types for the inputs and outputs, see Data Type Hierarchy.

Returns

Output {REAL or LREAL}

Example:

Function Block Diagram - LOG:

In this example, the input of 5 is provided by the CurrentValueFormatted property of a point. The LOG function converts the value into a base 10 logarithm value of 0.698970004336019 and this is used as the output.

ST Program - LOG:

The syntax for a LOG function in an ST Program is:

Output := LOG (Input 1);

Where Output and Input 1 are defined as variables earlier in the ST program. The Input 1 variable represents a REAL or LREAL type of value (the output is the same type of value as Input 1).