Tuesday, 20 October 2015

Difference between SCADA and DCS

As the internet bandwidth gets higher and higher, the difference between SCADA(Supervisory Control and Data Acquisition) and DCS(Distributed Control  Systems) is diminishing. Although a subtle line of discretion will always remain in their working, they are fast fading into each other. The basic difference, as suggested by the names, is that DCS is merely a control system, while SCADA is a control system too but it has the power to acquire data as well.

SCADA has been around for long, ever since Modbus became the preferred Machine to Machine (M2M) protocol. It was the top controller for low level intelligence machines, but it became a bit haphazard for a single system to control another system every second. Thus DCS started acting as a subordinate to SCADA. DCS was assigned most of the detailed work and its tasks were to take orders from and report to SCADA.

But the computers are so fast these days that the line of difference between Web Based SCADA and DCS is blurring fast. The difference is now only the region where you’re working, some workplaces call it SCADA and some call it DCS. But even after narrowing the margin, it is important to note how the two systems are actually different from one another. SCADA’s intelligence is distributed and even if communication is lost to the central hub, it can continue to control and monitor. DCS meanwhile, focuses on local problems and won’t be able to work if the communication goes haywire.

Basically, at control level a DCS is mainly concerned with the distribution control characteristics like control behaviours in field levels or local levels. SCADA on the other hand deals with control functions not only at the field or local levels but also at a supervisory level.