Understanding Flow Events
For Measures, the Flow Information Platform contextualizes information into time periods (e.g. hours, shifts, days, etc.). But what if we wanted to measure a KPI related to a specific production batch, or for a specific machine state? And what if we wanted to add additional context to that batch, like a product code, or to the machine state, like a downtime reason?
Flow Events can be used to extract this type of information from your data sources.
Flow Events are defined by triggers and attributes. Triggers are used to start and end event periods. Attributes are used to collect additional information associated with an event period to provide context (e.g. this was a batch of Orange flavored juice and the Batch ID was L1O0234).
In the Filler 1 example below, the historian is storing data related to the filler’s electricity usage (top tag) as well as its product run (bottom tag). The product tag is storing an integer value that represents the product being packaged for each filler run, or batch. The product tag also provides information about when the filler started and ended each production run.
Using a Flow Event definition, we can define the following:
- how to start each filler run period (start trigger)
- how to end each filler run period (end trigger)
- associate the product that was being packaged for each filler run (attribute)
- determine how much electricity was used for each filler run (measure)
When deployed, the Event definition starts a new event period each time the value of the Product tag changes from 0 to a positive number (green dotted line). The Event definition ends the event period when the value of the Product tag goes back to 0 (red dotted line). Flow then “overlays” the event period onto the electricity tag detail and calculates how many kWh were used for that filler run:
14027.9 (00:51:43) – 14079.8 (09:49:14) = 51.9 kWh
By repeating this process and mapping the product tag to a description, a simple transactional summary report of the kWh used per filler run, per product can be produced as follows: