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

LN

Function Name	LN
Description	Converts a REAL or LREAL input into a natural logarithm value that is the output. The natural 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

Description

Converts a REAL or LREAL input into a natural logarithm value that is the output. The natural 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 - LN:

In this example, the input of 5 is provided by the CurrentValueFormatted property of a point. The LN function converts the value into a natural logarithm value of 1.6094379124341 and this is used as the output.

ST Program - LN:

The syntax for an LN function in an ST Program is:

Output := LN (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).