In several occasions, it's needed to apply a simple formula based on the values coming from the field devices. For example, to calculate the average of two temperatures sensors or to sum the mass flow of a number of flow meters.

While you can achieve this via Scripts module that will be explained in a different chapter, Stream Gateway allows you to quickly apply a formula as the data source of a certain tag (More on that in Tags chapter).

From Stream Explorer, select Data Sources and click on the Add button.

There isn't much setting you need to configure to define a Calculation data source.

  • Name: Unique name for the data source.
  • Description: Optional information about the data source.
  • Protocol: Selecting Calculation defines this data source as calculation engine that we'll use later in Tags configuration.
  • Cycle (ms): Specifies the delay between each calculation cycle.

Note: Specify 1000 ms (default) if you have a low number of calculation tags. If you have a large number of calculations, consider slowing down the rate to retain CPU performance.