Unit Conversion Configuration

Overview

In the configuration editor UnitConversion, you define conversions which can be used for variables in visualization elements and in the IEC editors. Add the editor as an object UnitConversion in the Applications tree. You can rename it there.

UnitConversion editor

You can define various conversions for your project. Enter a Name and choose the Type for each. The respective conversion formula is automatically displayed in the Setting column. Enter a Condition to determine when the conversion should be executed. Depending on the selected Type, define specific parameters in the area below the table.

The editor provides the following conversion types:

Calculation with an offset: Single shifting (offset)
Calculation with a factor: Single scaling (factor)
Calculation with a factor and an offset: Linear scaling 1 (factor and offset)
Calculation with the base range and target range: Linear scaling 2 (base and target range)
Calculation with a user-defined expression: User-defined conversion
Different calculations depending on a variable value: Switchable conversion

For usage of unit conversions in IEC editors, refer to the chapter Usage in IEC Editors.

For usage of unit conversions in visualizations, refer to the chapter Using Unit Conversion in the Visualization part of the EcoStruxure Machine Expert online help.

Conditions

You can select 3 conditions to define when the calculation is executed:

Condition	Description
TRUE	The conversion is always performed.
Language	Language of the visualization (value of variable VisuElems.CurrentLanguage)
Variable	The conversion is performed depending on a variable value. The compare value can be a constant, a variable or an IEC expression.

Single Shifting (Offset)

Use this conversion if you want to add an offset to the input value.

(output value = input value + offset)

Parameter	Description
Offset	Value or variable

Single Scaling (Factor)

Use this conversion if you want to multiply the input value by a factor.

(output value = input value * factor)

Parameter	Description
Factor	Value or variable

Linear Scaling 1 (Factor and Offset)

Use this conversion if you want to multiply the input value by a factor and to add an offset.

(output value = (input value * factor) + offset)

Parameter	Description
Factor	Value or variable
Offset	Value or variable

Linear Scaling 2 (Base and Target Range)

Use this conversion if you want to calculate the value by defining the input and output range. A factor and an offset are calculated internally.

Parameter	Description
Base start value	Lower value of the input range
Base end value	Upper value of the input range
Target start value	Lower value of the output range
Target end value	Upper value of the output range

Example

Base start value: 0
Base end value: 1024
Target start value: 4.0
Target end value: 20.0

User-Defined Conversion

Use this conversion if you want to calculate the input value by a user-defined expression. Use the variable rValue as input value. In this expression, all IEC operands can be used.

Parameter	Description
Convert	Expression to convert the input value
Reverse	Expression to revert the calculated value

Switchable Conversion

Use this conversion if you want to use different conversions, depending on the language or a variable value. All defined conversions can be used.