What just happened and why ? - Unravel the domino effect with SOEs in SCADA

The Domino Effect

From at least the early 1990s when I discovered SCADA so to speak, I wondered what on earth SCADA meant by Sequence of Events and tended to reject the whole idea until I understood why ?

I had come myself from a world of real-time control when everything was current to the actual time and data from one controller was highly sequenced with that of another.  The era of the PLC and it's great contribution to sequencing of - read inputs, calculate logic, write outputs was a pretty fundamental design I had thought.

Are you Alert or just Waiting dear M2M machine

ALERT

Are you alert, or is it just waiting for the situation to pass.  Are you alert for something which might happen, something perhaps with danger requiring your constant situational awareness, or is it just waiting for the expected alarm when the pressure gets to high.

To what extent we confuse normal events, like the sun coming up and the sun going down with an alert meaning something just broke and you are in trouble or security was breached and you need to shutdown or burn everything.

Alerts are the output of a process which is monitoring the 'danger' domain, and the production of alerts needs to be meaningful, particularly when possibly mixed with Alarms, Events, Off-Normals and basic normal data.

How might we best characterize them ?

• Normal Data : No need to look at it - no need to act - maybe to fine tune - maybe to optimize, but no real danger involved and not a high priority.
• Event Data : Events record what happens, usually on a change of status of an item of plant, or perhaps an operator action for later audit purposes.
• ALARM : Alarms record a transgression of a limit or potential hazard developing.  Alarms are useful for managing situations post a disturbance event.
• ALERT : Alerts are a new category for most and I like to refer to Alerts as being from a higher form of intelligence and or situational awareness which characterize and inform of imminent danger or unexpected behaviour.

When observing animal behavior in the wild, you will see that the animal engages all of it's senses and the senses of it's herd to determine whether there is danger or not.  Animals often go from relaxed or waiting to high stages of alert within seconds based on the situation.  It is generally not just one input, but many which need to be correlated to determine that 'danger exists' and it is the function of 'situational assessment' to figure out whether 'danger' could exist.

Whether real-time systems are intelligent enough to correlate enough data to provide a higher level of reasoning required for an ALERT is a debate to be had, however we are now approaching the levels of computing and industrial software capability to provide a higher order ALERT system rather than the simpler more fundamental Data, Events and Alarm systems currently implemented.

Photo: Alert by paralog  under licence CC BY-ND 2.0