Nice video. One thing I might add is the DCS is usually designed with a narrower focus on process control. For example, implementing a complex cascaded multiple PID control scheme with constraints on a DCS can be done much more quickly and easily than a PLC. PLCs are more general purpose - you can implement the same control scheme but it will take longer, functions like tracking, reset limiting, signal selection, filtering and clamping sometimes need to be explicitly programmed so you really need to know the low level details (it could be argued PLCs are more powerful since you can make them do exactly what you want). DCS usually has a standard library of function blocks which cover pretty much everything you would ever need in process control. The PLC library is often more limited, extra functionality may be available at a cost however. Btw the function block diagram you've shown looks like modern ladder logic, quite a bit different to the typical DCS function block control drawing layout. The tight integration between the controllers, HMI (which you mentioned, but worth repeating) is a big deal. This can save many thousands of man hours on a large project if a DCS is chosen. Other notable differences: -Alarm configuration is typically more powerful in a DCS than a PLC/SCADA combination. -Fieldbus configuration is often tightly integrated with a DCS development environment, in fact some Fieldbus protocols common in continuous processing applications are not available or have only recently become available on PLCs. -System health assessment (via system alarms) in particular is tightly integrated within a DCS. You can see at a glance how the system is performing. -Operator keyboards providing key process control interaction funcitionality are standard with a DCS installation. Not to mention the seamless integration between DCS and SIS from the same vendor, but that's another story :)
Nice comment and you certainly know your DCS's. Agreed that there are some integration advantages with a DCS. Also, as you stated, most tasks can be performed in either, some more time consuming and challenging than others. In this video we were going for a more generalized, higher level difference. As you indicated, since the DCS may have a more narrow focus, many folks just jumping into the field don't really have even basic knowledge of a DCS system. Thank you for your comment!
Quite a good analysis: The PLC Shown in the video looks like the Siemens and the DCS is the ABB Freelance AC800F (originally form Hartmann & Braun Germany). I don't think it was the best choice of a DCS, as the AC800F is a low end DCS, quite near to PLC, quite far from the DCS ABB AC870P (ex Contronic S from Hartmann & Braun, previously Schoppe & Faeser) The AC800F does not require memory allocations of variable as you would in a PLC, it does have standard libraries for for PID's etc, but they are all quite simple and don't have standard tracking philosophy eg. in cascade control as you can would find in a AC870P. AC870P allows you to create your own complex PID structure, which could be quite difficult with an AC800F. With an AC870P you could create complex calculations and the system can automatically calculate the upstream tracking value. Both systems are freely programmable, you can create your own libraries, but you need quite a lot of experience to be able to create something close to the high level automation you can find in an AC870P
> Beau. Yes, sir, bullseye. The trade off's between configuration time (sometimes programming) vs. cost (of a more sophisticated and capable system) and other selection criteria, is the key. The old "Time is $". This video and your comments perfectly outline the big picture (PLC - DCS), but even within different makes & models of systems within each category, there are considerable cost vs. (built in) capabilities. Need batch sequencing and recipe flexibility? Better be sure systems being considered have the capability, so you're not hand crafting a "kinda-sorta" sequencing package (did that on a legacy system, we got there, but a lot of noodling dollars spent). There was even a large chem company that built their own DCS and claimed it was worth it, but they had a huge staff in house to program, install and maintain it. Virtually every other company uses the leverage of proven vendors systems, targeted to the nature of their environments, as you describe. And I do believe HMI integration and operator experience (aka "ease of use") is where a noticeable difference between integrated by design vs. programmed to communicate together, becomes apparent. Ask an operator to show how he/she performs a common task, start a pump, enter a set point, etc. and count the mouse clicks, a simple but meaningful test of well designed system, and ultimately, operator acceptance. I once talked to an operator who expressed "dissatisfaction" (his words were more colorful) with a brand new DCS that replaced a multi-decade old legacy system. But he could start a bank of pumps on the old system much faster/with many fewer mouse clicks.
Great video. In addition to the architecture explained in the video there is a bit more that shows each's benefit. In a DCS, it is extremely tough to program/maintain/trouble a sequential process (especially the ice cream example used). A DCS is better in a continuous process such a refinery where, for example, oil/gas is always flowing in out of the process. Pumps/valves rarely stop/close except during outages. This is because of the programming of function block diagrams. There is little to no need to dig into a function block diagram to see the code in a continuous process. A PLC is handled better for sequential processes. Being able to see all ladder logic helps to program/maintain/troubleshoot this process. If you used nothing but function blocks and AOIs, and a line went down, it would be tough to troubleshoot. You could have a hard time finding out what is causing an output from being energized. It could be power, a valve stuck in manual, or bit that got tripped up.
Great series from what I've seen so far and I'm thinking of sharing this with my non-I&C clients so that they have a better appreciation for what it is they're paying for and why we seem to ask a million questions when they ask for quotes :) One thing about the DCS is that historically, it was an evolution of traditional process automation, that is, everything that wasn't covered by relay logic, and it didn't just "invent itself" from trying to find something that's traditionally recognised a computer (i.e. a beige box or mainframe) would do. I realise that following that the following history would have taken the video off on a tangent and possibly lost some people but for the benefit of those who may be wondering "so what was before DCSs", here's some context for you ;) Whereas relay logic was predominantly the domain of sequential switching control, i.e. motor and solenoid on-off control, traditional process control - variable control - started back at the turn of the 20th century with mechanical controls. This evolved through the '40s and '50s into pneumatic controls with more complex mathematical functions, transitioning into analog electronic equivalents. All of these required external analogue computers to perform additional simple mathematic functions such as square root, addition, subtraction, multiplication, division, high-low select, and so on. When microprocessors hit the scene, initially these were employed predominantly in early DCSs due to cost. Whilst Distributed Control System is a clever marketing term, in brown-fields plants, these microprocessor-based controllers effectively replaced the area instrument panels ( a collection of single loop controllers and indicators), so in a sense, it could be countered that they actually integrated more than distributed process control. Controllers still existed in the same physical plant locations in most cases, but the control room could now be centralised - that was the kicker. Meanwhile, for the end-users who could not justify the expense of a DCS, microprocessors made their way into single-loop panel mount controllers, which initially didn't allow much in the way of user functionality over the analogue and discrete digital electronic version which they replaced. But when users had access to programmable microprocessor-based controllers, that's when configuration/programming of microprocessor-based single loop controllers really shone. As with the DCS, it was now possible to bring in up to four analog inputs and perform the mathematics which once required additional external devices. Complex control was becoming cheaper but you still needed panel space. Eventually, communications pathways were developed so that such single-loop controllers could be integrated with PLCs or DCSs and presented to the operator as a homogenous control system which was more DCS like than PLC. The falling cost of DCSs and PLCs - the latter in particular - has pretty much seen the single-loop controller relegated to simple local control panel duties in vendor equipment or commercial applications. Generally speaking, DCSs and PLCs (SCADA is effectively a PLC with telemetry tacked onto it) can do the job of each other in general applications but you'll see more PLCs in operation than DCSs for a reason and it's not because they're necessarily better, it's more about the application. For heavily sequential operations such as an assembly line or a mine-site, a PLC is cost-effective as it's fundamental design focus is high-speed switching with minimal complex computational functionality. For critical complex process automation (chemical, petrochem, etc.) the DCS remains the BPCS (Basic Programmable Control System) of choice since the design focus is on performing complex mathematical computations for a multitude of interactive complex control functions at high-speed. I wouldn't choose a PLC to control a mineral or petrochem facility, but likewise, I wouldn't select a DCS (purely on cost and wasted functionality) for a mine-to-shipping operation.
Thank you so much for your comment and the brief history of the evolution of the DCS. During the second year of my initial job after college (1981), I was charged with programming aFisher Provox system, serial number 2. Interestingly enough, the "brains" of this system was an HP 1000 minicomputer. The plant, up to that point, was controlled by >100 pneumatic controllers and a handful of Fisher AC2 and DC2 single-loop controllers. About a year later, I installed an IBM XT with a Burr-Brown data multiplexer to collect, store, report an alarm single-point emissions monitoring data. The program I wrote was a compiled version of BASIC. The oldest DCS I ever worked with was a FOX1 system with wire-wrapped memory cards (64 words each, not 64kWords), helium-filled drum memory, 340K disk platters, and a punch card interface. We have come a long way in 40 years! The tools have changed, but the principles of control (PID, sequencing, coordinated control, supervisory control, motor control, etc.) are still the same.
No problems, mate. Dust was blown off a few cranial cobwebs after watching this and the other videos. I cut my DCS teeth on a Honeywell TDC 2000 in 1980. I was a 2nd year Instrument apprentice on light duties following a work accident and had been given pretty much a data-entry clerk job entering the hand-written configuration that had been prepared for a phosphoric acid plant. During the process I ended up learning about what the configuration components meant and the basic structure of a DCS. That foundation made it easy to transition to the two versions of the Rosemount System 3 which we had in a chlorine plant and sodium cyanide plant respectively although by this time I was a supervisor and I was training my tradies to perform some of the configuration changes as well. Changing jobs and initially working as an I&C designer, I ended up programming a Bailey INFI90 system after someone discovered that I had DCS experience on my resume and after a few years programming, I ended up performing the duties of a Controls Systems Engineer in all but name and recognition. As for evolution, my only exposure to punch cards was in high school when I did computer programming as an option - I never progressed beyond the initial term because to my teenage head, it didn't make sense that you had to tell a computer what to do, it was supposed to know everything! Even though calculators had become mainstream in Australia by that time (1977), my year still used slide-rules and those of us who went to university would have had to use these for the entrance exam. Strange how the rose-coloured glasses of nostalgia consider the slide rule and tables a work of genius... but I'd rather use a calculator any day! :)
Simple explaination and comparison. Why dont you start showing the process of programming it from the beginning until the end on a certain equipment . Hope those effort will help thousand of people out there who had lost or currently thinking to create a new project or remodify something for a better purpose.
I worked with Modicon PLC controllers 184, 384 ,484 and finally 1084 systems. They were really reliable and easy to program.Hats off to the rugged design . We had 25 systems and i should proudly say none of the I/O modules nor CPUs failed for 25 years ,except few power supplies and RIO interface.
Working in controls this is what we consider a DCS system. Data collection system (DCS) is a computer application that facilitates the process of data collection, allowing specific, structured information to be gathered in a systematic fashion, subsequently enabling data analysis to be performed on the information.
I like that you touched on how using function blocks gives more capabilities and flexibility for uses of a PLC. However, I was a slight bit disappointed that you didn't touch on Script at all. This gives even greater flexibility to the programmer, and in some aspects even easier to program.
Thanks for the comment and observation. The intent of the video was just to give a basic overview of DCS and PLC. I use script a lot as well as function block and sequential function. I agree that script is a huge advantage for me but some old school programmers really don't like it because it strays from the standard ladder logic that most programmers are accustomed to. I was actually told by another programmer that script is the worst way to program, I whole heartedly disagree. Script is very powerful and I use it frequently. Thanks again and happy watching!
I am working as a Controls & Automation recruiter and trying to learn my market. Please keep up this amazing content as you're helping so much to learn about the things that Automation and Control engineers do everyday. If anyone can suggest anything else I should be trying to understand, i'd be most grateful :)
Great video. That fact that you missed was the DCS was used more in the past in large control systems because early PLC's were not capable of handling analog values. I saw a Honeywell DCS system completely replaced with Rockwell PLC's and a PC based HMI system. The 2 systems were almost identical to the process operator.
Thank for your comment. Using the DCS systems instead of PLC systems due to the incapability of the PLC systems in handling the analog values is of the early reasons in the late 80s, I believe. Nowadays, the PLCs became more sophisticated so that they are able to scale/unscale any kind of input and output.
Very good. I keep dipping my toes into learning more about PLCs as I think that they offer real advantages to what we do, but somehow haven’t taken enough steps to gain the confidence I need
A PLC could have a Primary Processor fail and take out a whole system as compared to one system in a DCS that goes down. But I guess if you maybe build the PLC system right and add redundancy with a Primary & Secondary Processor network, if that system ever going down it should be far less an issue. It should switch and barely skip a beat.
@7:59 so true - used to work at a plant that had an old DCS that was slowly being made obsolete via ABB acquisition (to push there DCS platforms). One contractor with specific programming/hardware experience had 3rd party near monopoly for a good chunk of West coast US, made a career out of it.
Hi Pragyesh! That is amazing! Great support. Please, let us know if you have any questions along the way. We are more than happy to help out! Are you also aware that we have a free course on PLC Hardware bit.ly/2XnnUrF Happy learning!
You should point out that today there are companies out there that provide the best of both worlds, such as Schneider Electric (Modicon) with their EcoStruxure Hybrid DCS solution. This provides the single database, single configuration, unified operator interface of a DCS along with the openness, scaleability and flexibility of a distributed PLC system. On top of that EcoStruxure Hybrid DCS also provides powerful run-time navigation services and support of redundant (hot standby) architectures. By the way, the name MODICON comes from MOdular DIgital CONtroller :-)
Most electrical engineers working in an industrial environment , metals, materials handling, mining or processing are conversant in both PLC and DCS programming and as pointed out the differences in operation and implementations are very similar. That said, that it is why things like stuxnet became a reality and an on going problem that will not go away. While we know about stuxnet and the variants that are similar but different made up of different and often from unrelated and unexpected blends of vulnerability and hence they don't go away or are permanently fixed.
Matti Mälkiä I agree. But how long does it take to troubleshoot, replace and reload PLC module? I guess a redundant system would be less cost effective too
Matti Mälkiä it depends. Generally, I would agree with you about the I/O. Depending on the manufacturers, redundant processors is easy. In the case of at least one platform I know of, redundant I/O is easy too.
Hi Natan, Thank you for your inquiry. You can establish a connection between a PH or RH device and either a PLC or a DCS system. By developing a program, you can receive signals from these devices and generate actionable results through an output or another signal. However, if your intention is to directly interface with a display or HMI, this can only be achieved if the HMI is integrated with a PLC or computer capable of receiving these signals. Wishing you a rewarding learning experience with RealPars!
Thank you for the free educational material provided for us and the wonderful style of explanation could you please told me what the program you use to create these great videos to do the same for my channel
Hi Essam, Thanks a million for your support! We are very happy to hear that you are enjoying our course videos so much. Have you had a chance to check out our free course on PLC Hardware, yet? bit.ly/2XnnUrF Regarding your question, I am not sure about this as this is done by our graphic and animation department. If you have any questions along the way feel free to reach back out! Happy learning!
Many aspects are not mentioned. The DCS has been process oriented from day one where PLCs more discrete. PLC vendors are trying to get there and are better in process but still not equal. Redundant control processors for example whereby a control processor in a DCS can be removed during operation, fail over with no affect on process - have done it many times. Communications capabilities of the DCS vs most PLCs, network redundancy, as well as incremental downloads and online programming of the DCS. I have seen PLCs that will go offline with down load - and fault on divide by 0!. For plants that have maintenance shut downs measured in years this is unacceptable. Also, cost. A DCS was once much more expensive where now a PLC based system that comes close to capabilities of a DCS with redundancy on network and control levels is often more expensive in PLCs and much more difficult to implement. Depends on your needs.
Thank you for your comments. In our RUclips videos, we are presenting a broad coverage of topics that are not meant to be exhaustive. Having implemented dozens of both DCS and PLC systems over my 38-year automation career, I have seen the trend firsthand of PLC's getting more powerful and DCS systems getting less expensive. It is important to note, that as a general rule, failover in DCS systems is more transparent than most PLC systems, but not all DCS systems are configured with failover CPU's. Most PLC's I work with now (ControlLogix, S7-400, etc.) also support online changes, incremental downloads, and redundant and fiber-based communications. Distinctions exist, so the best solution is the one that meets your specific needs the best.
A safe PLC has included redundancy. The code is compiled in two different compilers and executed on two different processors and it constantly self checks to ensure the outputs from the two different processors are in agreement. They are all generally TUV certified. On some systems, if you are using a standard PLC and a Safe PLC together, you can get cost savings from the Safe PLC using the processor in the standard PLC as its second processor, meaning the safe PLC will only need 1 physical processor.
Usually, yes you can have multiple control and monitoring stations connected to the DCS at the same time. You will need to have the proper licensing and application software, but concurrent sessions is one of the strengths of DCS systems.
There are PLC systems, DCS systems, and hybrid systems used for safety systems applications. What makes a piece of hardware suitable for safety applications is the testing that proves that hardware's reliability to be used in safety systems. There are independent tests that manufacturers subject their hardware to in order to receive the designation to be suitable for SIL1, SIL2, or SIL3 service. Hardware suitable for safety service will have different model numbers and likely will have a yellow housing to distinguish it from non-safety service. Many manufacturers have a safety PLC, DCS, and/or hybrid controller model line for use in safety systems.
@@realpars Hi, can a process be controlled and safeguarded on a single distributed PLC system that has both control functions and safety functions, or should these two be independent from each other (different distributed PLC system for safety on top of the already existing distributed PLC system for process control).
For anyone who's ever had a factory in MineCraft Tekkit and wondered if there was a real-life equivalent. ^^ (My proudest achievement was the fully automated kebab-stand, or the music trap, where if you fell into it, would be forced to listen to scary music)
This is a question people have been asking for yearst. When the term DCS was introduced, it referred to controllers and I/O networked together in a plant with a single-window interface, the operator station. This was quite a shift in architecture from the operator panel with switches and strip charts. Later, laboratories, pilot plants and other processes wanted to have the ability to monitor and control their processes, without the high cost of DCS systems. So PC-based SCADA systems were developed with board-level I/O and PC-based HMI applications. LabView was one of the first and is still the most widely-used of these SCADA systems. Over time, SCADA systems have become more and more powerful, and DCS systems have become less proprietary and lower cost. As a result, there is not a lot of difference between the two any longer.
You got a lot of things right on this video, but a lot of this information is extremely misleading. "You wouldn't want to control a single plant with one PLC," you said. I've never seen an entire plant small enough for a single PLC to control it, but PLCs are far more scalable than a DCS. Often a single PLC will be employed for a very limited system and will communicate with other such PLCs, creating a network of PLCs that is far more "distributed" than a DCS (Distributed Control System). And any DCS can have a controller fail, which would bring down a significant part of the process and other parts that relied on it in the flow of product. The platform you use is essentially irrelevant. You suggest that PLC programming is something of a commodity while DCS programming is highly specialized. That just isn't true; it's platform dependent. There are thousands of Rockwell programmers in the US, but far less Mitsubishi programmers, but both are PLCs. And for DCSs that have been around a while, you can find plenty of engineers with applicable experience. The thing you got most correct is that with the technology available today, almost any process can be successfully controlled with either a PLC or a DCS. The selection mostly depends on specific plant applications and company preferences.
Hi Mark, Thanks for the feedback and sorry for the delay here. Some of your points are well taken. Consider a small water treatment plant as a possibility for a single PLC control platform. I have seen many in my 20+ years that are certainly small enough for a single controller. Not sure which parts are extremely misleading but consider the video more history of PLC vs DCS as today, the lines are blurred. The differences in today's controlled environments are nearly indistinguishable.
Hi Geano, Thanks for your comment. No, we are posting different video courses in our RealPars Course Library. You won't find these RUclips in our Course Library just as you won't find our Course Library videos on RUclips. Hopefully, this clears things up. If you have any further questions, feel free to reach back out! Happy learning!
Question : is it possible for one controller to communicate with the other one in the DCS ? : Is it possible for one HMI to control more then one controller in any of the system
The short answer is YES. Most DCS suppliers have a method for communicating between controllers, often called peer-to-peer communication. The methods are usually different between manufacturers, but in most cases, this type of communication is not meant for large amounts of data transfer. And yes, the HMI stations will be able to monitor and control items from multiple controllers.
i dont have that much software and camera to do a vedio like you .bro if u help mr i will join your group and do it pls its will be more help full for me and my people
RAM KUMAR Thanks sir, Actually i didn't understand ...he try to say that both plc and dcs are same...but both have a difference...i didnt understand that difference..can anyone explain
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I am taking a mechatronics class and the teacher uses a lot of your videos. I always love them because it’s a break from the lectures.
Nice video. One thing I might add is the DCS is usually designed with a narrower focus on process control. For example, implementing a complex cascaded multiple PID control scheme with constraints on a DCS can be done much more quickly and easily than a PLC. PLCs are more general purpose - you can implement the same control scheme but it will take longer, functions like tracking, reset limiting, signal selection, filtering and clamping sometimes need to be explicitly programmed so you really need to know the low level details (it could be argued PLCs are more powerful since you can make them do exactly what you want).
DCS usually has a standard library of function blocks which cover pretty much everything you would ever need in process control. The PLC library is often more limited, extra functionality may be available at a cost however. Btw the function block diagram you've shown looks like modern ladder logic, quite a bit different to the typical DCS function block control drawing layout.
The tight integration between the controllers, HMI (which you mentioned, but worth repeating) is a big deal. This can save many thousands of man hours on a large project if a DCS is chosen.
Other notable differences:
-Alarm configuration is typically more powerful in a DCS than a PLC/SCADA combination.
-Fieldbus configuration is often tightly integrated with a DCS development environment, in fact some Fieldbus protocols common in continuous processing applications are not available or have only recently become available on PLCs.
-System health assessment (via system alarms) in particular is tightly integrated within a DCS. You can see at a glance how the system is performing.
-Operator keyboards providing key process control interaction funcitionality are standard with a DCS installation.
Not to mention the seamless integration between DCS and SIS from the same vendor, but that's another story :)
Nice comment and you certainly know your DCS's. Agreed that there are some integration advantages with a DCS. Also, as you stated, most tasks can be performed in either, some more time consuming and challenging than others. In this video we were going for a more generalized, higher level difference.
As you indicated, since the DCS may have a more narrow focus, many folks just jumping into the field don't really have even basic knowledge of a DCS system.
Thank you for your comment!
Quite a good analysis:
The PLC Shown in the video looks like the Siemens and the DCS is the ABB Freelance AC800F (originally form Hartmann & Braun Germany).
I don't think it was the best choice of a DCS, as the AC800F is a low end DCS, quite near to PLC, quite far from the DCS ABB AC870P (ex Contronic S from Hartmann & Braun, previously Schoppe & Faeser)
The AC800F does not require memory allocations of variable as you would in a PLC, it does have standard libraries for for PID's etc, but they are all quite simple and don't have standard tracking philosophy eg. in cascade control as you can would find in a AC870P.
AC870P allows you to create your own complex PID structure, which could be quite difficult with an AC800F.
With an AC870P you could create complex calculations and the system can automatically calculate the upstream tracking value.
Both systems are freely programmable, you can create your own libraries, but you need quite a lot of experience to be able to create something close to the high level automation you can find in an AC870P
Excellent detailed explanation. Thanks.
> Beau. Yes, sir, bullseye. The trade off's between configuration time (sometimes programming) vs. cost (of a more sophisticated and capable system) and other selection criteria, is the key. The old "Time is $".
This video and your comments perfectly outline the big picture (PLC - DCS), but even within different makes & models of systems within each category, there are considerable cost vs. (built in) capabilities. Need batch sequencing and recipe flexibility? Better be sure systems being considered have the capability, so you're not hand crafting a "kinda-sorta" sequencing package (did that on a legacy system, we got there, but a lot of noodling dollars spent).
There was even a large chem company that built their own DCS and claimed it was worth it, but they had a huge staff in house to program, install and maintain it. Virtually every other company uses the leverage of proven vendors systems, targeted to the nature of their environments, as you describe.
And I do believe HMI integration and operator experience (aka "ease of use") is where a noticeable difference between integrated by design vs. programmed to communicate together, becomes apparent. Ask an operator to show how he/she performs a common task, start a pump, enter a set point, etc. and count the mouse clicks, a simple but meaningful test of well designed system, and ultimately, operator acceptance. I once talked to an operator who expressed "dissatisfaction" (his words were more colorful) with a brand new DCS that replaced a multi-decade old legacy system. But he could start a bank of pumps on the old system much faster/with many fewer mouse clicks.
@@santopino2546 I would have liked for them to use abb new systems Symphony plus or 800xa. And automation architect or composser
Great video. In addition to the architecture explained in the video there is a bit more that shows each's benefit.
In a DCS, it is extremely tough to program/maintain/trouble a sequential process (especially the ice cream example used). A DCS is better in a continuous process such a refinery where, for example, oil/gas is always flowing in out of the process. Pumps/valves rarely stop/close except during outages. This is because of the programming of function block diagrams. There is little to no need to dig into a function block diagram to see the code in a continuous process.
A PLC is handled better for sequential processes. Being able to see all ladder logic helps to program/maintain/troubleshoot this process. If you used nothing but function blocks and AOIs, and a line went down, it would be tough to troubleshoot. You could have a hard time finding out what is causing an output from being energized. It could be power, a valve stuck in manual, or bit that got tripped up.
Great addition! Thanks for sharing that
Great series from what I've seen so far and I'm thinking of sharing this with my non-I&C clients so that they have a better appreciation for what it is they're paying for and why we seem to ask a million questions when they ask for quotes :)
One thing about the DCS is that historically, it was an evolution of traditional process automation, that is, everything that wasn't covered by relay logic, and it didn't just "invent itself" from trying to find something that's traditionally recognised a computer (i.e. a beige box or mainframe) would do.
I realise that following that the following history would have taken the video off on a tangent and possibly lost some people but for the benefit of those who may be wondering "so what was before DCSs", here's some context for you ;)
Whereas relay logic was predominantly the domain of sequential switching control, i.e. motor and solenoid on-off control, traditional process control - variable control - started back at the turn of the 20th century with mechanical controls. This evolved through the '40s and '50s into pneumatic controls with more complex mathematical functions, transitioning into analog electronic equivalents. All of these required external analogue computers to perform additional simple mathematic functions such as square root, addition, subtraction, multiplication, division, high-low select, and so on.
When microprocessors hit the scene, initially these were employed predominantly in early DCSs due to cost. Whilst Distributed Control System is a clever marketing term, in brown-fields plants, these microprocessor-based controllers effectively replaced the area instrument panels ( a collection of single loop controllers and indicators), so in a sense, it could be countered that they actually integrated more than distributed process control. Controllers still existed in the same physical plant locations in most cases, but the control room could now be centralised - that was the kicker.
Meanwhile, for the end-users who could not justify the expense of a DCS, microprocessors made their way into single-loop panel mount controllers, which initially didn't allow much in the way of user functionality over the analogue and discrete digital electronic version which they replaced.
But when users had access to programmable microprocessor-based controllers, that's when configuration/programming of microprocessor-based single loop controllers really shone. As with the DCS, it was now possible to bring in up to four analog inputs and perform the mathematics which once required additional external devices. Complex control was becoming cheaper but you still needed panel space.
Eventually, communications pathways were developed so that such single-loop controllers could be integrated with PLCs or DCSs and presented to the operator as a homogenous control system which was more DCS like than PLC. The falling cost of DCSs and PLCs - the latter in particular - has pretty much seen the single-loop controller relegated to simple local control panel duties in vendor equipment or commercial applications.
Generally speaking, DCSs and PLCs (SCADA is effectively a PLC with telemetry tacked onto it) can do the job of each other in general applications but you'll see more PLCs in operation than DCSs for a reason and it's not because they're necessarily better, it's more about the application.
For heavily sequential operations such as an assembly line or a mine-site, a PLC is cost-effective as it's fundamental design focus is high-speed switching with minimal complex computational functionality.
For critical complex process automation (chemical, petrochem, etc.) the DCS remains the BPCS (Basic Programmable Control System) of choice since the design focus is on performing complex mathematical computations for a multitude of interactive complex control functions at high-speed.
I wouldn't choose a PLC to control a mineral or petrochem facility, but likewise, I wouldn't select a DCS (purely on cost and wasted functionality) for a mine-to-shipping operation.
Thank you so much for your comment and the brief history of the evolution of the DCS. During the second year of my initial job after college (1981), I was charged with programming aFisher Provox system, serial number 2. Interestingly enough, the "brains" of this system was an HP 1000 minicomputer. The plant, up to that point, was controlled by >100 pneumatic controllers and a handful of Fisher AC2 and DC2 single-loop controllers. About a year later, I installed an IBM XT with a Burr-Brown data multiplexer to collect, store, report an alarm single-point emissions monitoring data. The program I wrote was a compiled version of BASIC. The oldest DCS I ever worked with was a FOX1 system with wire-wrapped memory cards (64 words each, not 64kWords), helium-filled drum memory, 340K disk platters, and a punch card interface. We have come a long way in 40 years! The tools have changed, but the principles of control (PID, sequencing, coordinated control, supervisory control, motor control, etc.) are still the same.
No problems, mate. Dust was blown off a few cranial cobwebs after watching this and the other videos.
I cut my DCS teeth on a Honeywell TDC 2000 in 1980. I was a 2nd year Instrument apprentice on light duties following a work accident and had been given pretty much a data-entry clerk job entering the hand-written configuration that had been prepared for a phosphoric acid plant. During the process I ended up learning about what the configuration components meant and the basic structure of a DCS.
That foundation made it easy to transition to the two versions of the Rosemount System 3 which we had in a chlorine plant and sodium cyanide plant respectively although by this time I was a supervisor and I was training my tradies to perform some of the configuration changes as well.
Changing jobs and initially working as an I&C designer, I ended up programming a Bailey INFI90 system after someone discovered that I had DCS experience on my resume and after a few years programming, I ended up performing the duties of a Controls Systems Engineer in all but name and recognition.
As for evolution, my only exposure to punch cards was in high school when I did computer programming as an option - I never progressed beyond the initial term because to my teenage head, it didn't make sense that you had to tell a computer what to do, it was supposed to know everything! Even though calculators had become mainstream in Australia by that time (1977), my year still used slide-rules and those of us who went to university would have had to use these for the entrance exam. Strange how the rose-coloured glasses of nostalgia consider the slide rule and tables a work of genius... but I'd rather use a calculator any day! :)
You could also add that a PLC system can execute the logic at a much faster rate than the DCS does. Great video!
Great point! Thank you, Elvis
Simple explaination and comparison. Why dont you start showing the process of programming it from the beginning until the end on a certain equipment . Hope those effort will help thousand of people out there who had lost or currently thinking to create a new project or remodify something for a better purpose.
I worked with Modicon PLC controllers 184, 384 ,484 and finally 1084 systems. They were really reliable and easy to program.Hats off to the rugged design . We had 25 systems and i should proudly say none of the I/O modules nor CPUs failed for 25 years ,except few power supplies and RIO interface.
Thanks for sharing that with us!
Working in controls this is what we consider a DCS system.
Data collection system (DCS) is a computer application that facilitates the process of data collection, allowing specific, structured information to be gathered in a systematic fashion, subsequently enabling data analysis to be performed on the information.
Thanks for sharing your knowledge with us!
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Excellent move of mr. Morley.
The animations of your videos are impressive
Thanks a million! We appreciate that
Appreciate the free lessons. Ignore those giving a thumbs down. They're drunk.
Happy to hear that you're enjoying the videos!
You're drunk
I like that you touched on how using function blocks gives more capabilities and flexibility for uses of a PLC. However, I was a slight bit disappointed that you didn't touch on Script at all. This gives even greater flexibility to the programmer, and in some aspects even easier to program.
Thanks for the comment and observation. The intent of the video was just to give a basic overview of DCS and PLC. I use script a lot as well as function block and sequential function. I agree that script is a huge advantage for me but some old school programmers really don't like it because it strays from the standard ladder logic that most programmers are accustomed to. I was actually told by another programmer that script is the worst way to program, I whole heartedly disagree. Script is very powerful and I use it frequently. Thanks again and happy watching!
I am working as a Controls & Automation recruiter and trying to learn my market. Please keep up this amazing content as you're helping so much to learn about the things that Automation and Control engineers do everyday.
If anyone can suggest anything else I should be trying to understand, i'd be most grateful :)
Thank you Alex, happy to hear that!
If then can you help to know what the industry need now and how it helps the industry
Great video. That fact that you missed was the DCS was used more in the past in large control systems because early PLC's were not capable of handling analog values. I saw a Honeywell DCS system completely replaced with Rockwell PLC's and a PC based HMI system. The 2 systems were almost identical to the process operator.
Thank for your comment. Using the DCS systems instead of PLC systems due to the incapability of the PLC systems in handling the analog values is of the early reasons in the late 80s, I believe. Nowadays, the PLCs became more sophisticated so that they are able to scale/unscale any kind of input and output.
Al Ryan : you can do all that now with the AB studio 5000 logix designer
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Very good. I keep dipping my toes into learning more about PLCs as I think that they offer real advantages to what we do, but somehow haven’t taken enough steps to gain the confidence I need
Glad it was helpful! Keep up the learning curve, Michael!
@@realpars mere pass
A PLC could have a Primary Processor fail and take out a whole system as compared to one system in a DCS that goes down. But I guess if you maybe build the PLC system right and add redundancy with a Primary & Secondary Processor network, if that system ever going down it should be far less an issue. It should switch and barely skip a beat.
@7:59 so true - used to work at a plant that had an old DCS that was slowly being made obsolete via ABB acquisition (to push there DCS platforms). One contractor with specific programming/hardware experience had 3rd party near monopoly for a good chunk of West coast US, made a career out of it.
Was it Baldor? I took a tour of that plant after they installed some of the robotic automation for assembling some of their larger stators and rotors.
Very simple and excellent way of explanation. Thank you
Thanks for your support, Akmal! Happy to hear that.
Every video adds up my knowledge. Good work. Keep it up...
Happy learning!
I love this...do not let anyone stand in your way... I agree with time management vs. personal time..
Very nice comparison... Good work dear real Team
Thanks for your support, Mohammad! Great to hear that.
i just suscribed your youtube channel, followed on instagram facebook and downloaded your app. cant get enough of you
Hi Pragyesh!
That is amazing! Great support. Please, let us know if you have any questions along the way. We are more than happy to help out!
Are you also aware that we have a free course on PLC Hardware bit.ly/2XnnUrF
Happy learning!
Really good education
Thank you, David!
You should point out that today there are companies out there that provide the best of both worlds, such as Schneider Electric (Modicon) with their EcoStruxure Hybrid DCS solution. This provides the single database, single configuration, unified operator interface of a DCS along with the openness, scaleability and flexibility of a distributed PLC system. On top of that EcoStruxure Hybrid DCS also provides powerful run-time navigation services and support of redundant (hot standby) architectures. By the way, the name MODICON comes from MOdular DIgital CONtroller :-)
Thanks for sharing that with us!
Your videos are very precious for us!
Great to hear that!
Good presentation sir. Always following your videos.
Amazing, great to hear that!
Happy learning, Harish!
Awesome video for best learn, I am interested for pro pack
Glad you liked it and happy to hear that! You can register via the following link learn.realpars.com/bundles/pro
Very clear and concise explanation - well done.
Thanks, ray!
Excellent video will definitely recommend this channel to others!!
Great to hear, Paul! Thanks for your support!
This is rocking. Cleared my doubt
Great to hear!
Thank you for creating such a wonderful video
You are very welcome, Kavin!
Thank you very much.
You are very welcome!
Oh I love Real Pars!
Thank you Jobin! Happy to hear that!
Good electric knowleage video
Thank you!
What is the R-control Ei800.. It used for control drive servo motor
Loving the weekly uploads
Stay tuned for the next week! :)
Great idea 💡
Great video
Glad you enjoyed it!
Thanks Realpars
You are very welcome! Happy learning!
So many process sir...nice video
Thank you, Darnos!
Most electrical engineers working in an industrial environment , metals, materials handling, mining or processing are conversant in both PLC and DCS programming and as pointed out the differences in operation and implementations are very similar. That said, that it is why things like stuxnet became a reality and an on going problem that will not go away. While we know about stuxnet and the variants that are similar but different made up of different and often from unrelated and unexpected blends of vulnerability and hence they don't go away or are permanently fixed.
Thanks for the comment, Richard. As automation engineers, we need to take these kinds of threats seriously.
Your channel rocks
Thanks a lot, Pablo!
Single-point failure in PLCs can be removed with redundant PLCs. Though its pain in the ass to program and test.
Matti Mälkiä I agree. But how long does it take to troubleshoot, replace and reload PLC module? I guess a redundant system would be less cost effective too
Matti Mälkiä it depends. Generally, I would agree with you about the I/O. Depending on the manufacturers, redundant processors is easy. In the case of at least one platform I know of, redundant I/O is easy too.
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Thnks a lot for your useful information
Thank you, Mostafa! Happy learning and let us know if you have any questions along the way!
Thanks for informative videos and tutorials
Superb! Thank you.
Thanks for watching!
Thanks for sharing
Nice video for about the plc
Excelent!
Can please make videos related to calibration of field instruments
Hi Krishna, thanks for the topic suggestion, I will definitely go ahead and forward this to our creator team. Happy learning!
The best channel at the moment
:)
Very good video. Could you please discuss about PLC vs PC-based control?
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thanks for the video
Thanks for watching!
Very informative, Thanks
You're very welcome!
Excellent video! I like how is explained the difference between plc and Dcs .
Happy to hear that. Thanks for sharing your positive feedback with us!
Thank , this will be too much helpful for me.
Glad you found this helpful!
please make videos on scada tutorial
Hey!
Thanks for your comment and your suggestion. I will pass this on to our course developers!
Thanks for sharing and happy learning!
Can we connect PH and RH detecter sensor in on display or transmitter?
Hi Natan,
Thank you for your inquiry. You can establish a connection between a PH or RH device and either a PLC or a DCS system. By developing a program, you can receive signals from these devices and generate actionable results through an output or another signal. However, if your intention is to directly interface with a display or HMI, this can only be achieved if the HMI is integrated with a PLC or computer capable of receiving these signals. Wishing you a rewarding learning experience with RealPars!
Thank you dear
You're very welcome!
thanks dear very useful video thanks a lot .
Thank you!
Nice video
Wish you a million subscribers !
Haha! That would be awesome! :)
Thank you for the free educational material provided for us and the wonderful style of explanation could you please told me what the program you use to create these great videos to do the same for my channel
Hi Essam,
Thanks a million for your support! We are very happy to hear that you are enjoying our course videos so much.
Have you had a chance to check out our free course on PLC Hardware, yet? bit.ly/2XnnUrF
Regarding your question, I am not sure about this as this is done by our graphic and animation department.
If you have any questions along the way feel free to reach back out!
Happy learning!
@@realparsthanks alot for your interesting and hope more success for you and your team
A very good video, Thanks a lot
You're very welcome! :)
very good
Many aspects are not mentioned. The DCS has been process oriented from day one where PLCs more discrete. PLC vendors are trying to get there and are better in process but still not equal. Redundant control processors for example whereby a control processor in a DCS can be removed during operation, fail over with no affect on process - have done it many times. Communications capabilities of the DCS vs most PLCs, network redundancy, as well as incremental downloads and online programming of the DCS. I have seen PLCs that will go offline with down load - and fault on divide by 0!. For plants that have maintenance shut downs measured in years this is unacceptable. Also, cost. A DCS was once much more expensive where now a PLC based system that comes close to capabilities of a DCS with redundancy on network and control levels is often more expensive in PLCs and much more difficult to implement. Depends on your needs.
Thank you for your comments. In our RUclips videos, we are presenting a broad coverage of topics that are not meant to be exhaustive. Having implemented dozens of both DCS and PLC systems over my 38-year automation career, I have seen the trend firsthand of PLC's getting more powerful and DCS systems getting less expensive. It is important to note, that as a general rule, failover in DCS systems is more transparent than most PLC systems, but not all DCS systems are configured with failover CPU's. Most PLC's I work with now (ControlLogix, S7-400, etc.) also support online changes, incremental downloads, and redundant and fiber-based communications. Distinctions exist, so the best solution is the one that meets your specific needs the best.
Sir can u please make video on difference between plc and safety plc
Thanks for the comment. We will consider your request.
A safe PLC has included redundancy. The code is compiled in two different compilers and executed on two different processors and it constantly self checks to ensure the outputs from the two different processors are in agreement. They are all generally TUV certified. On some systems, if you are using a standard PLC and a Safe PLC together, you can get cost savings from the Safe PLC using the processor in the standard PLC as its second processor, meaning the safe PLC will only need 1 physical processor.
perfect
Nice video!
Can i connect the dcs end cable with two pcs have same application control and monitoring
Usually, yes you can have multiple control and monitoring stations connected to the DCS at the same time. You will need to have the proper licensing and application software, but concurrent sessions is one of the strengths of DCS systems.
Thank you ; Really you a the HERO
Thank you! :)
very very good
I like that.
Interesting for repetitive production.
Light and photocell work quieter than relay
I always appreciate real parts video. Can you please give me Training about scada of Siemens.
Hey Mahmud!
Thanks for your comment and your suggestion. I will pass this on to our course developers!
Thanks for sharing and happy learning!
@@realpars , can you please send me your email address? My address: mahmud.boni@gmail.com
Good
Very good! The PLC is usually used for Basic Control Process Systems and the DCS for Safety Systems or there is not this relation?
There are PLC systems, DCS systems, and hybrid systems used for safety systems applications. What makes a piece of hardware suitable for safety applications is the testing that proves that hardware's reliability to be used in safety systems. There are independent tests that manufacturers subject their hardware to in order to receive the designation to be suitable for SIL1, SIL2, or SIL3 service. Hardware suitable for safety service will have different model numbers and likely will have a yellow housing to distinguish it from non-safety service. Many manufacturers have a safety PLC, DCS, and/or hybrid controller model line for use in safety systems.
@@realpars lots of thanks!
@@realpars Hi, can a process be controlled and safeguarded on a single distributed PLC system that has both control functions and safety functions, or should these two be independent from each other (different distributed PLC system for safety on top of the already existing distributed PLC system for process control).
useful knowledge
Thank you!
Exelent information
Thank you!
For anyone who's ever had a factory in MineCraft Tekkit and wondered if there was a real-life equivalent. ^^ (My proudest achievement was the fully automated kebab-stand, or the music trap, where if you fell into it, would be forced to listen to scary music)
That was funny! :)
Wow! This is a great video, thank you
Happy to hear that! You're very welcome!
Thumbs upkeep up the good work
Thank you, Asaad!
Besten Dank (Y)
i love too much
thanks from peru
Gracias, Alex!
And whats the difference btween SCADA and DCS? Is its their database size?
This is a question people have been asking for yearst. When the term DCS was introduced, it referred to controllers and I/O networked together in a plant with a single-window interface, the operator station. This was quite a shift in architecture from the operator panel with switches and strip charts. Later, laboratories, pilot plants and other processes wanted to have the ability to monitor and control their processes, without the high cost of DCS systems. So PC-based SCADA systems were developed with board-level I/O and PC-based HMI applications. LabView was one of the first and is still the most widely-used of these SCADA systems. Over time, SCADA systems have become more and more powerful, and DCS systems have become less proprietary and lower cost. As a result, there is not a lot of difference between the two any longer.
@@realpars wow man...thanks for such a complete answer!
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Perfect 👍👍
Thanks!
Please make video on 800XA DCS with redundant AC 800M and it's I/o's. Specially Wiring
Hey Sagar!
Thanks for your comment and your suggestion. I will pass this on to our course developers!
Thanks for sharing and happy learning!
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good good
You got a lot of things right on this video, but a lot of this information is extremely misleading. "You wouldn't want to control a single plant with one PLC," you said. I've never seen an entire plant small enough for a single PLC to control it, but PLCs are far more scalable than a DCS. Often a single PLC will be employed for a very limited system and will communicate with other such PLCs, creating a network of PLCs that is far more "distributed" than a DCS (Distributed Control System). And any DCS can have a controller fail, which would bring down a significant part of the process and other parts that relied on it in the flow of product. The platform you use is essentially irrelevant. You suggest that PLC programming is something of a commodity while DCS programming is highly specialized. That just isn't true; it's platform dependent. There are thousands of Rockwell programmers in the US, but far less Mitsubishi programmers, but both are PLCs. And for DCSs that have been around a while, you can find plenty of engineers with applicable experience. The thing you got most correct is that with the technology available today, almost any process can be successfully controlled with either a PLC or a DCS. The selection mostly depends on specific plant applications and company preferences.
Hi Mark, Thanks for the feedback and sorry for the delay here. Some of your points are well taken. Consider a small water treatment plant as a possibility for a single PLC control platform. I have seen many in my 20+ years that are certainly small enough for a single controller. Not sure which parts are extremely misleading but consider the video more history of PLC vs DCS as today, the lines are blurred. The differences in today's controlled environments are nearly indistinguishable.
Agreed, I was as a lead control system engineer for biogas plants and our plants are controlled off a single s7-1500 controller
I'd like to know if all this youtubes videos are included in the Realpars website courses?
Hi Geano,
Thanks for your comment.
No, we are posting different video courses in our RealPars Course Library. You won't find these RUclips in our Course Library just as you won't find our Course Library videos on RUclips. Hopefully, this clears things up.
If you have any further questions, feel free to reach back out!
Happy learning!
Thank you for the quick answer.
can i have to tutorial of PM571 installation
Hi there, I will pass your request on to our creator team.
I am surprised, why such channels get a few likes?
Nurbol Shmitov dude what is a plc in 2018?#^😎
Question : is it possible for one controller to communicate with the other one in the DCS ?
: Is it possible for one HMI to control more then one controller in any of the system
The short answer is YES. Most DCS suppliers have a method for communicating between controllers, often called peer-to-peer communication. The methods are usually different between manufacturers, but in most cases, this type of communication is not meant for large amounts of data transfer. And yes, the HMI stations will be able to monitor and control items from multiple controllers.
A lot of PLC and DCS are using TCP-IP to communicate with.
Dear Realpars, Can you teach BAS?
Hi Reasmei,
Thanks for the topic suggestion, I will definitely go ahead and forward this to our creator team.
Happy learning!
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Thanks friend. I want to working with you. How to have opportunity?
You are very welcome! We are currently not hiring unfortunately.
Hi i need to retake this vedio in tamil for my tamil nadu people
Hi there, feel free to embed the video!
i dont have that much software and camera to do a vedio like you .bro if u help mr i will join your group and do it pls its will be more help full for me and my people
RAM KUMAR
Thanks sir,
Actually i didn't understand ...he try to say that both plc and dcs are same...but both have a difference...i didnt understand that difference..can anyone explain
nice
What is the name of the controllers used in dcs? Are they plcs or have another name?
Most of the time, they are called "Controllers". In PCS7, they are called "Automation Stations" or AS.
@@realpars I will not call PCS7 a DCS system :) :) :)
Super