Concept
Units
Building Operation supports both the SI metric system and the US Customary System for units of measurement.
There are four optional ways to display units:
As MS Windows
As configured in object
International System of Units (Metric)
United States Customary Units (US)
For example, the temperature 42,82 °C is stored in Building Operation. A WorkStation on an operating system with the US Customary System converts the temperature and displays it as 109.08 °F.
As MS Windows
By default, values are converted into the unit given by the regional settings of the operating system.
As configured in object
Units displayed as configured in the object means that no conversion is done. The unit the user selected when creating, for example, a trend log is displayed regardless of regional settings. When this option is selected, the unit conversion exceptions feature is disabled.
International System of Units (Metric)
Values displayed in International System of Units means that the values are converted into metric unit regardless of the unit the object was given when created.
United States Customary Units (US)
Values displayed in United States Customary Units means that the values are converted into US unit regardless of the unit the object was given when created.
When you select a different unit system, the values are converted immediately.
Values are not converted in the following WorkStation screens:
Alarms and trend logs in wizards
Customized alarm views
Alarm and trend log properties panes
Building Operation converts the unit of a variable independent of its context. To correctly convert a delta temperature, the unit of the delta value must belong to the unit category Temperature Diff.
The conversion between Celsius and Fahrenheit or Fahrenheit and Kelvin is not a simple coefficient (multiplier) like other unit categories as for example length, pressure, currency, and Energy. Due to the conversion formula when for example converting an absolute Fahrenheit temperature to Celsius, T°F=T°C x 9/5 + 32, you have both a multiplier and an offset to consider. To correctly convert a delta temperature from Fahrenheit to Celsius you have to use the formula ΔT°F = 9/5 ΔT°C.
For more information, see Delta Temperature Conversion .
Value Presentation
Regional and Language Overview
Changing the WorkStation Measurement System
Unit Selection Dialog Box
Adding or Changing a Unit and Prefix for a Value
Configuring Regional Settings
Delta Temperature Conversion