The system calculates formulas in regular intervals, or when a new connection is drawn between two shapes. Some calculations can take several minutes to complete, especially when a new connection was just drawn, because the system will calculate the values based on the earliest values it finds in the database.
If you want to use the outputs of a data point calculation as an active control signal (e.g. as a water alarm), you might want the calculation to be executed faster, and the value should be written to the bus immediately, rather than stored in the databse.
For this use case, you can enable the option Automatic Writing in the Properties sidebar of any of your regular data point shapes.
If you do so, the system will actively listen to changes on any of the input data points connect to this shape. In case of a change, the calculation will be executed and the resulting value will be written to the bus data point.
The value written to the bus data point is not stored in the database, i.e. data points with this option enabled have no data history.
To use this feature, a special license is required.