Use engineering units

About engineering unit

Engineering unit is the metric by which data values for a particular tag are measured; for example, RPMs, milliseconds, or degrees. Engineering Units are case-sensitive. (Also called unit of measure.)

You have to map the engineering units to the relevant Engineering Unit catalog. For more information on defining custom engineering units, see the Define custom engineering units section in the AVEVA Insight Online Help.

Converting engineering units for tags in BI Gateway

For a given tag or a group of tags, a value reported in an engineering unit belonging to the same Engineering Unit catalog dimension (For example, Energy, Mass Flow, Area, Power, Pressure, and so on) as other engineering units available in Insight can be converted using the Expression parameter in BI Gateway.

Leveraging the Expression parameter for a group of tags enables you to convert and normalize value of each of the tags in the group to a given output Engineering Unit.

You can use Engineering Units in the AnalogSummary, CQAnalogSummary, CQProcessValues, ProcessValues, and ProcessValues for time defining dimension queries. If you want to convert Engineering Units for the tags defined in any of these queries, ensure that you use the Tag parameter in that query.

Consider a scenario where a query contains multiple tags. If the destination Engineering Unit is defined only for one tag, the conversion happens only for that tag. The other tags which do not have a destination Engineering Unit assigned return the default Engineering Unit.

For example, the following query contains Temperature and Humidity tags. However, the destination Engineering Unit (°C) is applicable only for the Temperature tag. Therefore, the conversion happens only for the Temperature tag, and the Humidity tag returns the default Engineering Unit.

{

"QueryName": "AnalogSummary",

"SelectColumn": ["FQN","StartDateTime","OpcQuality","Minimum","Maximum","Average","StdDev","Integral","Count"],

"Tag": {

"Filter":"FQN eq 'Weather.Los Angeles.Temperature' or FQN eq 'Weather.Los Angeles.Humidity'",

"Select":"FQN"

},

"StartDateTime": "[RequestedStartTime]",

"EndDateTime": "[RequestedEndTime]",

"Expression":"UOM(°C)"

}

Note:
- If you do not pass any value to UOM(), a validation error occurs. To ensure that the validation is successful, you have to pass a valid engineering unit. For example, UOM(ºC) and UOM(t/h)
- If a tag does not have the assigned destination Engineering Unit, then the default Engineering Unit is returned.