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Tutorial 08: Create a new Tag

Result

Understand how to create a Flow Tag from an item in a data source’s namespace

Tutorial steps

  1. Drag a tag – Drag and Drop an item from the data source namespace to create a  tag under the correct Metric in the Model
  2. Confirm defaults – confirm that defaults are set as per defaults bar and Historian properties
  3. Confirm data processing – confirm data is being retrieved from the data source's tag
  4. Confirm entries in the Change log – confirm your operations had been logged in the change log of the measure

You are going to create a measure for the Boiler Temperature under the "Steam" folder in your Flow Model. But before we can create the measure, we first need to create a Metric inside the "Steam" folder.

Drag the Metric icon from the Flow Zone onto the "Steam" folder …

This will create a metric named "New Metric" which you can immediately name as "Steam"

Locate the 010-TT-001.PV Boiler Temperature tag from the Historian, drag it across to the Model View and drop it onto the "Steam" metric.

 

Notice what has happened …

When you dropped the tag onto the metric, Flow created a measure for you. By default, the name of the measure is the same as the tag used to create the measure from the specific data source.

Also, notice how the icon describes a few of the measure’s properties:

As soon as you add a tag to the model, it is ready to start retrieving data from the data source. However, it won't actually retrieve any data until you use it within another measure (e.g. an hourly measure) or within a pass-through chart, or if you ask for the data using the Flow API (more on pass-through charts and the API in the Advanced Training!)

Rename the measure to "Temperature". 

Measure Editor

Let’s have a look at what is happening behind the scenes. Double-click on the new measure to open its Editor …

General Properties

The top section of the Measure Editor displays a few general properties for the Measure:

  • Description – Measure description (in this case, the description was pulled through from the Historian tag’s description)
  • Format – report format used to display the summary values (in this case, 1 decimal place)
  • Unit – unit of measure (in this case, the unit of measure was pulled through from the Historian tag’s engineering unit. This is why we didn’t need to set the Default Unit of Measure.)

Data Preview

By default, the Data Preview section will show a chart of the raw data for the last 30 minutes. In this case, the Start and End of Period has been adjusted to display both the raw data chart and grid views for the last 3 days.

To hide/display the Chart or Grid views, toggle the respective buttons in the top left of the Data Preview. 

Notice the information provided in the grid:

  • Timestamp – the data & time at which the raw value was retrieved.
  • Duration – the duration (since the last data point, or since the start of the period if this is the first data point) in milliseconds.
  • Value – the formatted raw value retrieved from the Historian.

Retrieval

Expand the "Retrieval" section. Notice that this section contains information about the tag you dragged across from the Historian Namespace.

  • Data Source - the name of the Data Source from which you dragged and dropped the tag.
  • Tag – the "Historian" tag for which raw data is retrieved (this was populated during the drag n’ drop action, but can be edited if required, another tag can also be dragged over this textbox). If the data source is a SQL, this will be replaced with a Query textbox

Dependents

This section displays any other objects in your Flow System that depend on this measure. Examples include:

  • Other tags that use this tag in calculations
  • Measures that may use this tag in aggregations
  • Pass-through charts

Change Log

This section displays a change log for this specific measure, from creation to deployment. Any changes that are made to the measure’s configuration will be logged here.

To confirm the Change Log functionality, change the Description to "Boiler Temperature (Primary)". Refresh the Change Log and notice the new log entry relating to the description property change.