Add an engineering unit

After you add an engineering unit, you can configure both existing and new analog tags to use the new engineering unit.

Note: Engineering units are case-sensitive. That means AVEVA Historian differentiates between ml (milliliters) and ML (megaliters), for example.

To add an engineering unit

1. In the Operations Control Management Console, expand a server group and then expand a server.

2. Expand Configuration Editor, expand System Configuration, and then expand Tag Configuration.

3. Right-click Engineering Units, and then click New Engineering Unit. The New Engineering Unit wizard displays.

   

4. Enter the Unit Name.

5. In the Tag Rate box, enter the default rate, in milliseconds, at which tags are cyclically stored, based on engineering units. Although the system does not make use of this engineering unit based tag rate, you can reference this value in custom SQL scripts. The value you enter for this tag rate does not affect the default storage rate set for the tag.

6. Select the appropriate Dimension for the engineering unit. The values displayed in this list are a combination of the available dimensions from the database, and the unit system in parentheses.

7. Select a Canonical Unit for the engineering unit. This list contains all visible units from the Engineering Units Catalog corresponding with the selected dimension. See Configure the engineering units catalog for more information.

   Notes: Some units with the same name or symbol may have different definitions in different unit systems, so take care to select the correct unit. For example, the U.S. gallon and imperial gallon have different volumes.
   
   While it is possible to map multiple engineering units to the same canonical unit, to avoid confusion it is not recommended. For example, you could choose to create three engineering units named liters, litres, and L, and map them all to L in the engineering units catalog.

8. Click Finish.