Before you create a measure that retrieves data from the “Historian”, let’s setup a few Default Measure settings.
Browse through the Historian’s Namespace until you find tags relating to the Juice Factory’s Boiler. Hover over these tags to see a brief description of what they represent. Using the description and the engineering units, you should get a good idea of what these tags are.
Let’s focus on the Temperature tag, 010-TT-001.PV, measured in ˚C. The value of this tag is most likely being stored in the Historian at high-resolution, possibly every second.
To report on this temperature, you want to create a Flow measure that stores the average temperature every hour. You want to report the average temperature to 1 decimal place (i.e. 98.2 ˚C). You also know that your Historian has a few months of data already stored, so let’s go back and retrieve the average temperature for every hour as far back as we can.
Given that you know a few of the settings required to report on the Boiler Temperature, it is useful to pre-select the Measure defaults as described on page 25.
Select the following:
- Default Time Base – set this to Hourly since we want an hourly summary of the temperature.
- Default Format – set this to 0.0 (to give us 1 decimal place).
- Default Unit of Measure (UOM) – ignore this for now because the Historian supports engineering units.
- Default Backfill Date – set this to the beginning of last month (notice the hour starts at 06:00 based on our calendar definition).