The differences between IoT, SCADA и DCS

The term “Internet of Things” (IoT) is used everywhere, but how do people even understand what this means? Often, the Internet of Things is used where it would be more accurate to use another term, and when trying to define it, the definitions are not very compatible with each other.

Let’s try to figure out what it really is.

Where did the Internet of Things come from?

The phrase “Internet of Things” itself emerged as a common headline in a presentation about RFID (radio frequency identification) in supply chains back in 1999. Of course, this is not about the fact that only this should be called the Internet of Things, but nevertheless, pay attention to what changes the meaning of the term has undergone over the past 20 years.

In most publications on the Internet of Things, this term can simply be replaced by SCADA (Supervisory Control And Data Acquisition). Or DCS (Distributed Control System). The meaning of the text will not change at all

Instead of “Internet”, the network of the circuit element will be meant, and the “Thing” will be the sensor. At the same time, no one pays special attention to where and what this conventional sensor is measuring, be it a temperature sensor in the bedroom or a temperature sensor in a steam boiler of a power plant. Although, I must admit, in the case of a power plant, words like “industrial” or “technical process” are sometimes added. But from a technical point of view, this does not affect anything, so let’s agree to ignore this division.

Some people stress that the Internet of Things implies a high level of reliability, but this is also not a universal rule. Or rather, not related only to the Internet of Things.

Consider the engine of a modern aircraft and its monitoring systems. Let’s say the engine has a sensor that monitors its condition. During the flight, the data from the engine, most likely, will not be sent over the Internet somewhere far away: they will go to the aircraft’s internal monitoring system. At the same time, reliability is extremely important here, because the flight is the very time when some problems with the engine can lead to a disaster.

But after landing, at the airport, the same engine can be monitored through the same sensor, loading archived (archived during flight) and actual data into a centralized analytics system. Here, the reliability of the data is no longer as important as in flight. However, it is on the ground in this example that the engine becomes part of the Internet of Things – but not in flight, when reliability is much more important.

Where you can really find the differences between the Internet of Things and SCADA or DCS is in the dependency model, or other words, in the data acquisition patterns.

There are “interactive” applications (SCADA and DCS), where:

• the operation of the application depends on the synchronous process of receiving data, and the data is perceived as a stream of entities;

• data acquisition depends on devices (sensors, activators, etc.), and they, as well as the data transmitted by them, are predefined.

And there are “jet” ones (not in the sense of an aircraft engine, but the context of a reaction to something).

This is the Internet of Things:

• the process of receiving data is asynchronous, data is a stream of events;

• the data source depends on the data transmission channel;

• the asynchronous process of receiving data depends on the data transmission channel.

Details can take a long time. But the main difference is precisely in these approaches to data.


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