What are the Differences between DCS and SCADA?

Summary

This video script from RealPars offers a comparative analysis between SCADA and DCS systems, highlighting their similarities and differences. It explains that while both systems are used for plant supervision and control, they differ in their Human Machine Interface (HMI) integration, with DCS having a more integrated approach, eliminating the need for additional software. The script also touches on the programming aspects, noting that DCS systems facilitate faster integration with predefined functions, but SCADA systems may offer faster processing times. It concludes by emphasizing that the choice between SCADA and DCS depends on specific project requirements, such as communication architecture openness, time sensitivity, and safety concerns.

Takeaways

• 🤖 Both SCADA and DCS are systems used for supervision and control of plants, with similar roles in automation.
• 🖥️ SCADA systems present data to operators for decision-making and control plant functions, while DCS has a similar role but is typically integrated within the system.
• 📊 HMI (Human Machine Interface) panels serve as the primary graphical interface for interaction between operators and automated processes in both SCADA and DCS systems.
• 💻 HMI panels can come from various manufacturers or be industrial computers, requiring additional software for programming, except in DCS where they're often integrated.
• 🔗 SCADA systems may use different manufacturers for PLCs, RTUs, and HMI, whereas DCS typically has integrated interfaces, reducing the need for extra software.
• 🛠️ Programming in SCADA involves writing code for controllers, with the possibility of reusing code through custom function blocks and Add on Instructions (AOIs).
• 🚀 DCS systems have predefined functions that facilitate faster integration, though they still require some coding.
• 🕒 Processing times in DCS can be slower compared to SCADA, which might affect time-sensitive processes.
• 🔌 Communication in SCADA systems is adaptable to changing technologies, while DCS also adapts but may have proprietary communications that are challenging.
• 🛡️ For safety-critical applications, DCS is traditionally preferred, but modern SCADA systems with safety processors are also viable options.
• 📈 In the current market, the choice between SCADA and DCS depends on specific needs such as processing speed, communication architecture, and safety requirements.

Q & A

What are the main components of a SCADA system?

A SCADA system consists of both software and hardware components that enable supervision and control of plants, both locally and remotely.

How is a DCS similar to a SCADA system?

A DCS, like a SCADA system, is a collection of components used for supervising and controlling plant operations, with the goal of automating processes.

What is the primary function of an HMI panel in plant automation?

Human Machine Interface (HMI) panels serve as the primary graphical interface between plant processors and the operators, allowing interaction and control of processes.

Can HMI panels be procured from different manufacturers?

Yes, HMI panels can be procured from various manufacturers such as Siemens, Allen Bradley, GE, Schneider Electric, or independent manufacturers like Red Lion.

What additional software is typically required for programming an HMI?

Additional software is needed to program an HMI, such as WinCC for Siemens, FactoryTalk View for Allen Bradley, Vijeo Designer or Citect for Schneider Electric, depending on the manufacturer.

What is the advantage of using the same manufacturer for both PLC and HMI?

While it might seem advantageous to use the same manufacturer for PLC and HMI, it does not necessarily mean that the tag database of the processor will be available for use in the HMI, as some vendors require exporting, importing, or creating tags from scratch.

How do SCADA and DCS systems differ in terms of their graphical interfaces?

SCADA systems may use HMIs or computers from different manufacturers, while DCS systems typically have integrated graphical interfaces within the DCS system, eliminating the need for additional software.

What are the 'brains' of a SCADA system?

The 'brains' of a SCADA system include Programmable Logic Controllers (PLCs) and Remote Terminal Units (RTUs), which require programming to execute essential plant operations commands.

How have DCS systems facilitated faster integration in plant automation?

DCS systems have many predefined functions that can be customized and deployed for various applications, which helps in faster integration by reducing the time spent on writing code for commonly used functions.

What is the impact of slower processing times in DCS systems?

Slower processing times in DCS systems may impact time-sensitive processes, although this is not necessarily problematic as it depends on the specific requirements of the plant operations.

How do SCADA and DCS systems compare in terms of safety?

While DCS systems have traditionally been favored for safety-critical applications due to their proprietary communications, modern SCADA systems can also be selected for safety-critical applications with the use of safety processors.

What are the key differences between SCADA and DCS systems in today's market?

In today's market, DCS systems offer integrated operator interface software with tag databases, while SCADA systems require additional software purchases and the building or importing of tags. SCADA may have a slight advantage in time-sensitive processes due to faster processing times, and offers an open communication architecture advantage.

Outlines

00:00

🤖 Introduction to SCADA and DCS Systems

This paragraph introduces the topic by referencing previous discussions on SCADA (Supervisory Control and Data Acquisition) and DCS (Distributed Control System), providing links to those videos in the description. It sets the stage for a comparative analysis between the two systems, highlighting their roles in plant automation and supervision. The paragraph emphasizes the importance of understanding the fundamentals of SCADA and DCS to answer the question of whether they are essentially the same. It also touches on the use of Human Machine Interface (HMI) panels as the primary graphical interface between operators and automated processes, mentioning various manufacturers and the need for additional software to program these HMIs.

05:02

🔍 Comparison of SCADA and DCS Interfaces and Programming

This paragraph delves into the comparison of SCADA and DCS systems, focusing on the interfaces and programming aspects. It discusses the advantages of DCS's integrated operator interface software and tag databases, which eliminates the need for additional software purchases. In contrast, SCADA systems often require separate software and the building or importing of tags. The paragraph also addresses the 'brains' of the operations, such as PLCs (Programmable Logic Controllers) and RTUs (Remote Terminal Units) in SCADA, and the predefined functions in DCS that facilitate faster integration. It mentions the processing times and the impact on time-sensitive processes, as well as the communication aspects of both systems. The paragraph concludes by suggesting that while DCS may have an edge in safety due to its proprietary communication, SCADA systems have become competitive in safety measures and offer faster processing times and open communication architecture.

Keywords

💡SCADA

SCADA stands for Supervisory Control and Data Acquisition, a system of software and hardware that enables remote monitoring and control of industrial processes. In the video, SCADA is compared with DCS, highlighting its use for gathering data, making decisions with operator input, and controlling plant functions based on those decisions. It is noted that SCADA systems may require additional software for HMI programming and may have faster processing times, which could be advantageous for time-sensitive processes.

💡DCS

DCS stands for Distributed Control System, which is a platform for automated control and operation of a plant or industrial process. Unlike SCADA, DCS typically has integrated operator interface software and tag databases, eliminating the need for additional software purchases. The video points out that DCS systems may have slower processing times but offer advantages in safety-critical applications due to their proprietary communication protocols.

💡HMI

Human Machine Interface (HMI) refers to the primary graphical interface used by operators to interact with and control automated processes in a plant. HMIs can be procured from various manufacturers or can be industrial computers that meet specific requirements. They typically require additional software for programming, which can vary depending on the manufacturer. The video emphasizes that while SCADA systems use HMIs, DCS systems have integrated interfaces that do not require extra software.

💡PLC

A Programmable Logic Controller (PLC) is a digital computer used for automation of industrial processes, including manufacturing and production lines. PLCs are a component within SCADA systems that require programming to execute commands essential for plant operations. The video script mentions that over time, methods have been developed to consolidate and reuse code in PLCs, which has improved efficiency in automation.

💡RTU

A Remote Terminal Unit (RTU) is an electronic device that interfaces a remote station with a supervisory system, typically used in industrial automation and control systems. RTUs, like PLCs, are part of SCADA systems and require programming to perform their functions. They are responsible for gathering data from the field and transmitting it to a central control system.

💡FactoryTalk View

FactoryTalk View is a human-machine interface (HMI) software package developed by Rockwell Automation, specifically for use with Allen Bradley programmable logic controllers (PLCs). It is used to create interfaces that allow operators to monitor and control industrial processes. The video script mentions FactoryTalk View as one of the software options required for programming HMIs in SCADA systems.

💡WinCC

WinCC is a software suite for HMI (Human Machine Interface) and SCADA (Supervisory Control and Data Acquisition) systems developed by Siemens. It is used to create visual interfaces for monitoring and controlling industrial processes. The video script mentions WinCC as the software needed for programming Siemens HMIs, emphasizing the additional software requirements for SCADA systems.

💡Vijeo Designer

Vijeo Designer is a software package for creating and configuring human-machine interfaces (HMIs) used in industrial automation. It is developed by Schneider Electric and is compatible with their Modicon PLCs. The video script mentions Vijeo Designer as one of the software options required for programming HMIs in SCADA systems.

💡Citect

Citect is a software suite developed by Schneider Electric for creating supervisory and control applications, often used in conjunction with their HMI systems. It is part of the suite of software options that are necessary for programming HMIs in SCADA systems, as mentioned in the video script.

💡Intellution

Intellution is a software package for creating and managing human-machine interfaces (HMIs), typically used in larger-scale automation environments. It is one of the software options mentioned in the video for interfacing with plant processes in SCADA systems, where a desktop computer is used instead of an HMI panel.

💡iFix

iFix is a software platform for creating and deploying human-machine interfaces (HMIs) and is part of the Wonderware suite of industrial software solutions. It is used in SCADA systems for larger-scale automation environments, where a desktop computer serves as the interface between operators and the plant processes.

💡VtSCADA

VtSCADA is a software package designed for creating supervisory control and data acquisition (SCADA) systems. It is used in larger-scale automation environments where a desktop computer is the interface between operators and the plant processes. The video script lists VtSCADA as one of the software options for SCADA systems, highlighting the need for specialized software in such environments.

Highlights

SCADA and DCS are both systems used for supervision and control of plants, with similarities in their components and purposes.

SCADA systems are designed to gather data, make decisions with operator input, and control plant functions based on those decisions.

DCS's role in plant automation mirrors that of SCADA, but with differences in their mechanisms and operations.

Human Machine Interface (HMI) panels serve as the primary graphical interface between plant processes and operators.

HMI panels can be procured from various manufacturers or can be industrial computers, requiring additional software for programming.

Using the same manufacturer for PLC and HMI may not always provide the advantage of a shared tag database.

HMIs are typically used in small-scale automation, while larger systems may require desktop computers with their own software packages.

DCS systems have integrated graphical interfaces, which is advantageous as it eliminates the need for additional software.

SCADA systems may use PLCs and RTUs, which require programming to execute essential plant operations commands.

DCS systems have predefined functions that facilitate faster integration, though they still require custom coding.

Processing times in DCS are generally slower than in SCADA environments, which could impact time-sensitive processes.

SCADA systems have adapted to changing technologies and offer more flexibility in communication compared to the proprietary communications of DCS.

Safety is often a priority for DCS systems, but modern SCADA systems with safety processors are also viable options.

In the current market, the differences between SCADA and DCS systems are not as pronounced, with each having its own set of advantages.

DCS offers integrated operator interface software and tag databases, while SCADA requires additional software and tag management.

For time-sensitive processes, SCADA may have a slight advantage due to faster processing times.

SCADA provides an advantage in terms of open communication architecture.

When concerned about safety, DCS is often the preferred choice.

The video aims to clarify the similarities and differences between SCADA and DCS systems, aiding viewers in understanding their unique features.

Transcripts

In previous discussions, we have presented detailed information about both SCADA and DCS

which you can find the links to these videos in the description area.

In this conversation, we will contrast and compare both systems.

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click the like button below.

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As you have previously learned,

a SCADA system is a collection of both software and hardware components

that allow supervision and control of plants, both locally and remotely.

A DCS is also a collection of components used for the same purpose.

These similarities may lead you to ask then: Are they essentially the same?

To answer that question let’s look back to the fundamentals of both systems.

You may recall that a SCADA system is used to gather and present data to operators,

make decisions about processes with the aid of operator input,

and control plant functions based on those decisions.

The DCS’s role in plant automation is the same as the SCADA system.

Since we already know that the role of the SCADA and DCS systems are essentially the same,

let’s try to compare and contrast the mechanisms used to handle those tasks

versus the operations themselves.

Let’s start with the device that plant personnel use to interact with the automated processes.

Human Machine Interface (HMI) panels

are the primary graphical interface between the plant processors and processes

and the operators interacting with and controlling those processes.

We had provided a video previously on “What is an HMI?”.

You can follow the link to this video in the description area

to watch it and grasp more information about Human Machine Interfaces.

The HMI panels can be procured from the same manufacturer as the controller,such as Siemens,

Allen Bradley, GE, and Schneider Electric, all of which produce their brand of HMI panels.

There are also independent HMI panel manufacturers such as Red Lion.

Yet still, the HMI can be an industrial computer from Dell

or any other manufacturer that meets the rugged requirements for the PC.

While most of the manufacturers may have their own brand of HMI,

typically, additional software is needed to program the HMI.

In the case of Siemens, WinCC software, Allen Bradley requires FactoryTalk View,

Schneider needs Vijeo Designer or Citect, and so on.

There may be some PLC/HMI programming software

that is integrated for the manufacturer but for the most part,

they are separate software packages requiring separate purchases.

Having the same vendor of PLC and HMI may seem to be an advantage but as noted,

the requirement for additional software is definitely not beneficial.

You would also think that using the same manufacturer would allow you to have the tag database of your processor

available for use in the HMI, not necessarily true.

Some vendors do have drag and drop capabilities, such as GE.

However, most of them require exporting and importing

while others require the creation of the tags entirely from scratch.

HMIs are primarily used in small scale automation environments.

When you have larger-scale systems,

the interface with the plant process is typically a desktop computer.

This computer requires its own software package

such as Intellution or iFix, Wonderware, or VtSCADA to name a few.

While a SCADA system has HMIs or computers that are not necessarily of the same manufacturer,

the DCSs have graphical interfaces that are typically integrated within the DCS system.

As you can imagine, this is a definite plus

as the requirement for additional software is not needed.

And, as a bonus, the tags within the DCS are available for use, without much additional effort.

Based on the interface descriptions of SCADA and DCS,

clearly, the DCS has the advantage in this category.

Now let’s discuss the brains of the operation.

Within the SCADA system, there may be PLCs and RTUs.

As you are aware by now, these components require programming

in order to execute commands essential to plant operations.

Earlier in automation history,

there may have been thousands of lines of code to run a single process in a plant.

As the years have gone by, more and more ways to consolidate and reuse code have been implemented.

This reusable code still needs to be written in a format that is used by the controller.

Custom function blocks, Add on Instructions (AOIs), etc.,written in the controller by a programmer.

Once written, the code can be instantiated any number of times for use within the controller.

It may take quite a while to develop a library of code that can be used over many projects.

While this was, at least in the earlier days, more cumbersome in the SCADA implementation,

the DCS had many predefined functions that could be customized

and deployed for various applications.

This didn’t eliminate the need to write code however,it did help to facilitate faster integration

because less time would be spent writing code for commonly used functions.

Processing times are somewhat slower in the DCS versus the PLC/RTU SCADA environment.

While this is not necessarily problematic,

it could have an impact on processes that are very time sensitive.

Communications within a SCADA system can vary widely

and have adapted to the changing technologies while the DCS has also adapted,

there are still some proprietary communications that can be challenging.

It has been said that if safety is a priority then the DCS is the route to go.

However, nowadays, with the abundance of safety processors, a SCADA system may also be selected.

To sum things up, in today’s market, there are not massive differences in the systems.

DCSs have integrated operator interface software with tag databases,

while SCADA requires you to purchase additional software and build or import your tags.

If you have a very time sensitive process,

SCADA systems may have a slight advantage as the processing time is faster.

Need an open communication architecture? Advantage SCADA.

Concerned about safety? Advantage DCS.

As you can see, there are a lot of similarities between the two systems.

Either way you go, hopefully this video has shed some light on both the similarities

and differences between the two systems.

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