Creating an Events Stream for SCADA Systems

An Events stream will indicate in its Samples table whenever a data sample crosses over a threshold. You then need to only configure in the SCADA system the static rules that apply when samples cross the threshold.

This functionality is useful if you use a SCADA system – and not the Ayyeka management UI – for monitoring and management.

Use Case

Although SCADA systems receive stream data, they do not get indications of events. An event is any occurrence of a sample value crossing a threshold, which triggers the Threshold Actions defined for the threshold. It is true that you can manually program the SCADA system with thresholds and alerts that correspond to the Threshold Actions defined in the Ayyeka management UI. However, no notifications are sent to the SCADA system whenever changes are made in the Ayyeka threshold actions, and even if the SCADA integrator is notified manually, the SCADA thresholds and actions need to be changed accordingly.

The solution offered by the Events stream is to disassociate a threshold from its specific range of values (which are changeable), and associate it only with its index number (which is fixed). For every stream you can define in the Ayyeka UI five threshold levels, which in the Events stream are designated by index numbers 1 - 5, with 1 being the very lowest threshold and 5 being the very highest.

An Events stream will indicate, in its Samples table, whenever a data sample crosses over into another threshold, by displaying the index number of threshold. You need then only to configure once in the SCADA system the static rules that apply when samples cross over into each threshold. 

For example, suppose we have a level stream for which we configured three thresholds:

1: the range of values from minus infinity – zero

2: the range of values from 0 – 5

3: the range of values from 5 – infinity

The Samples table of that Events stream will then look similar to the example shown below. That is, in addition to displaying the Datetime and Raw Value of each sample, it displays in the Final Value column the threshold number in cases where the sample crosses a threshold.

Note that no value is displayed in the Final Value column so long as the sample value remains within the current threshold.



To create an Events stream:

  1. In the left pane, click Devices.
  2. In the Sites Tree pane, click the device name, and then click the stream name.
  3. In the right pane, click Configuration & Threshold tab, and then click Create Events Stream.
  4. In the Create Events Stream window that appears, click Submit. An Events Stream is created for the selected data stream.