10 Major Differences between DCS and SCADA?

Introduction to DCS and why is it called distributed control system?

DCS and SCADA both are industrial control systems this control system plays a major role in industrial automation. We can use DCS to control complex processes, as the name indicates DCS is a distributed control system. In this control system, there would be a lot of sub-control systems and all of these control systems would be integrated together into a central control system.

Importance of DCS in Industrial plant

DCS can be used in a huge industrial plant if there are a lot of panels and I/Os and all of them should be connected to a central control system then we can utilize the distributed control system. DCS has good reliable features and it can be used to control an entire plant.

If you need better efficiency and safety for your industrial plant then you can choose DCS, this control system would reduce the maintenance of the plant. We can use DCS on a medium scale and also in large-scale industrial plants. DCS is used to control big systems, there would be a server in the DCS.

All the data from the sub-control system would be collected in the DCS server like the data from the boiler, turbine, and also from other processes would be collected here. Mostly in this system, there would be a single server but there would be a lot of controllers.

Introduction to SCADA

SCADA is also an industrial control system and it also plays a major role in the industrial automation sector. SCADA does the supervisory control and data acquisition, so we can do the supervisory control with the help of SCADA. The major advantage of SCADA is that you don’t need to be in an industrial plant or in an office to control the industrial process.

You can remotely control and access the data in an industrial plant by using SCADA and that’s why it is called a supervisory control system. You can use SCADA remotely and can give instructions to the employees based on the received data.

SCADA would require an internet connection and graphical interface to operate, it is a high-level supervisory control. SCADA is software by which you would be able to control the process distantly.

How SCADA control system is different from a DCS control system?

As we discussed earlier a SCADA system is a supervisory type of control system we can access data from anywhere if we have an internet connection. SCADA system would be composed of software and hardware. We can describe the distributed control system as a factory-centered system but we can’t say the same in the case of the SCADA. If you have several companies on different sites they could be in different countries.

Then all of these industrial companies can be interconnected by using the SCADA system and all these data could be gathered with the help of the SCADA system.

So the major advantage of the SCADA is that we can visualize and control the process from anywhere. The DCS would control the process in a factory so it’s a short distance communication when compared to SCADA. Because of the short distance communication, the communication speed of the DCS is really fast. The SCADA communication system is slow because of distant communication.

DCS system is really redundant and it is due to the fact that there would be two controllers for a system. So each unit in the industrial plant would have two controllers so the safety and reliability of the DCS control system are really high. The DCS control system would cost more than the SCADA control system.

Due to the redundancy and safety of the DCS system, the downtime and maintenance cost would be really low. The distributed control system would control the industrial process, DCS system would be composed of controllers, sensors, etc. So the DCS system is mostly dependent upon the instrumentation. DCS systems would be preprogrammed while the SCADA is not preprogrammed.

So due to this most of the control functions will be already in the DCS, in the case of the SCADA system, it needs to be programmed. A DCS system would be composed of controllers, HMIs, and I/Os.

SCADA would utilize certain peripherals such as programmable logic controllers and also the PID controllers to interact with the machinery and process plant. The operation of the DCS is entirely based on the process while the SCADA operation is dependent on data gathering.

The distributed control system would utilize a network to connect the controllers, sensors, operator terminals, and also many other field devices in the industrial plant. So due to this interconnection if there is any fault then it can be determined and also can rectify it very quickly.

The major part of the SCADA system is the graphical user interface and also the connection to the industrial plant via the internet. We can also describe the supervisory control system as an HMI system because it can interact with the operator very easily through the graphical interface. The important feature of the distributed control system is that it is capable to implement advanced process control techniques due to the multiple controllers.

The supervisory control system won’t be able to do the advanced process control as much as the distributed control system. The distributed control system mostly uses its hardware to gather the process data. In the case of the supervisory control, it would mostly utilize the software to gather data

Difference between DCS and SCADA

How is a PLC different from a DCS?

PLCs are used to control a single machine while the DCS would be able to control several machines or processes. Mostly we can control an entire plant by using DCS. We can control a process from different parts of the industrial plant with the help of the DCS, due to its distributed control features. In the case of PLC, it won’t be possible because wherever the PLC is connected it would control that section.

DCS would have a lot of inputs and outputs when compared to the PLC. Mostly PLC would be used for the batch units while DCS is for a distributed unit. We can use the DCS to control almost all the processes in a plant so DCS can be used for distance control applications. The computing speed of the DCS is really fast when compared to the PLCs because the capacity of the controllers in the DCS is really high.

How SMEClabs can help you to achieve your dream career?

So now you know the importance of DCS and SCADA in the industrial sector. If you are planning to start a career in the Automation sector then SMEClabs could educate you and guide you. We would also give you industrial exposure and thus you can improve your skills. There are a lot of automation job vacancies in the offshore sectors and also in most of the industrial sectors.

Automation has made many changes in the industrial sector, and the opportunities in this sector are increasing a lot. So while choosing this course you don’t need to worry about the opportunities in this field. If you take the automation course with SMEClabs, you can learn a lot about PLC, SCADA, DCS, PAC, industrial robotics, HMI & VFD, and a lot more. After completing this course from SMEClabs you would get international certification.

Author – Ashlin A J