This makes it easier to implement and maintain. The speed of logic execution is another key differentiator between DCS and PLC. One advantage of IPCs is that it is often possible to run the HMI application on the same machine as the automation program and decrease cost. Check out our free e-newsletters to read more great articles.. ©2020 Automation.com, a subsidiary of ISA, A subsidiary of the International Society of Automation. For example, take the server halls of data centres: these types of control systems are often seen as hybrids of both DCS and PLC. S Bharadwaj Reddy May 1, 2019 January 30, 2020. A connected PLC system can have nearly the same security and robustness as a DCS, while a single PLC is a single point of failure, so you wouldn’t want to control an entire plant with a single PLC. Basically, the creation of a DCS system came about because of the increasing use of microcomputers. In her free time, Anderson is a RealPars video instructor. This advantage occurs because of the autonomous controller can be located in close proximity to the process versus pulling long runs of I/O wire across a plant. In an earlier article, I have explained the top 25 advantages and disadvantages of PLC over the relay system. The reduced hardware and software requirements reduces cost. One of the drawbacks to the DCS has been the scarcity of programmers that have some experience with it. PLC-A could process the ice cream batch. Reliability. A DCS combines one or more PLCs with an HMI, and allows the integrator to build both together. The takeaway from this comparison is that, with today’s technologies, either system can control an entire plant. Function block programming, if you aren’t familiar with it, is a section or several lines of code behind a single interface. After finding financial support, Morley’s new enterprise, Modicon, was created. Future of the DCS/PLC . In this article, I tried to cover all the PLC basics required. A DCS's regulatory control loops generally scan in the 100 to 500 millisecond range. In her lengthy career, Anderson has worked in a wide variety of industries, and with all of the top PLC systems, as well as the top names inHMI/SCADA. Important Issues . DCS stands for Distributed Control System. This kind of predictive analysis is particularly important for obsolete part replacement and avoiding costly downtime. The idea of using a PLC-based system rather than a DCS has become a philosophical and technical debate in the industry. All upgrades are made online while the system runs continuously. The PLC received device information from the field, solved the logic, and then energized the outputs to produce the desired effect, which generally meant performing repetitive tasks in a reliable and durable manner. Boom…GM heard about Morley’s work and eventually contracted with Modicon to purchase over $1 million worth of their innovative programmable controllers (it was several years later, when personal computers or PCs were invented and the “logic” part of the name was added to create the term, PLC). Another advantage is the onboard monitoring and control system. PLC-Easy provides a lean-tested framework where functionality for every type of process and industry, as well as MES supporting functionality/data, can be easily created, added and modified by using basic programming skills. For example, take the server halls of data centres: these types of control systems are often seen as hybrids of both DCS and PLC. That’s when Morley began to think outside the box, literally. Mark Proctor gives his analysis of DCSs and PLCs in the modern plant. The data can be displayed in various formats as per user requirements. Benefits or advantages of SCADA. It is also no longer as cumbersome either - modern DCS hardware resembles a PLC in size. This is why DCS is now used in smaller applications, whereby it is not spread across the whole plant, but rather a complex subsection that needs reliable control. The best way to think about DCS and PLC is like this: in the majority of cases, a PLC controls a machine and a DCS controls a plant. Your PLC is more like a utility player - he's nippy and doesn't mind where he plays, but don't expect him to be as reliable as your captain. Based on the current rate of technological advancement, most experts agree it will be pointless to differentiate between DCSs, DDCs, and PLCs in the future. Because of the specialized training, DCS programmers are a bit harder to come by. Conversely, PLCs are often used when the value of the product is relatively low and production needs to be flexible. There is no monitoring devices in PLC like DCS. It is also no longer as cumbersome either - modern DCS hardware resembles a PLC in size. After the ice cream batch was complete, another autonomous controller would process the freezing of that ice cream. The advancement of the microprocessor resulted in a merging of the technologies. Bayt.com is the leading job site in the Middle East and North Africa, connecting job seekers with employers looking to hire. Fig. The PLC is cost effective from 0 to a few thousand I/O points. Every day, thousands of new job vacancies are listed on the award-winning platform from the region's top employers. There had been other computer-based systems in the industry since the late 1950s, but these had limited scopes for scalability, robustness, and security. 2. In the beginning, the PLC was used primarily for discrete controls. Mondi Anderson works as a Controls Engineer at Metawater USA, a global company focused on water treatment technologies, equipment and engineering. A DCS combines one or more PLCs with an HMI, and allows the integrator to build both together. 3. It was over 35 years ago that the first DCS systems were installed in glass industry processes. He shared it with his team who enthusiastically embraced the design. You can slap in as many controllers and networks as you can afford. This allows them to accurately control motors and drives running at high speeds. Redundancy. It has capable to communication with computer in plant. In a nutshell, a PLC or programmable logic controller is a ruggedized computer used for automating processes. crossed that line and put a PLC with HMI in charge of a con-tinuous process control application. The company name stuck through a couple of acquisitions, then morphed into what is now Schneider Electric. These days, there is probably no single factory in the word that … “The ability to employ a single, hybrid control strategy that combines the benefits of both DCS and PLC/HMI control is a huge advantage for a company today, enabling them to run completely different processes from the same controller environment,” Ryan said. This change has brought about a certain level of technological convergence between PLCs and DCSs that defies traditional ideas of the two. For all their differences, PLC and DCS are becoming more alike. A distributed control system (DCS) centralizes plant operations to provide flexibility and simplicity by allowing central control, monitoring and reporting of individual components and processes. You can reach her at: mondi.anderson@gmail.com, or email the RealPars team at: hello@realpars.com. Some uses of IPCs include OEM machines and skids and other small projects where space is limited. Essentially, the difference between PLC and DCS forty years ago was considerable, and if you owned a large plant with continuous processes, you likely would have chosen a DCS. A DCS typically covers an entire process, and is capable of covering an entire plant. So if you have a large facility with parts of your process strewn throughout, then a DCS will assist you better. The difference between distributed control systems (DCSs) and programmable logic controllers (PLCs) can be boiled down to a simple football metaphor. Benefits of DCS for Hybrid Industries versus Conventional PLC Approach: Your questions answered Webcast presenters Jerry Espy, Frank Prendergast, and Jerry Bartlemay answered questions about topics such as cybersecurity risk, the emergency of the … On the other hand, engineers expect a DCS to offer an out-of-the-box control system with features such as - historian, sophisticated alarms and logic from pre-existing function blocks. By Mondi Anderson, Controls Engineer at Metawater USA and Automation Instructor at RealPars. Abig differentiator of DCS over PLC/SCADAis the standardisation they provide. PLCs are fast, no doubt about it. This is why DCS is now used in smaller applications, whereby it is not spread across the whole plant, but rather a complex subsection that needs reliable control. In addition, today's DCS hardware is not as expensive as it was a couple of decades ago and is less difficult to implement. Figure 2. In most small to medium size applications a single processor (though this is changing now too) has immediate access to all data and I/O and processes it as required. There are many advantages that a PLC system holds over a relay system. Traditionally, a DCS system was expensive, large, complex to implement and only seen as a control solution for continuous or complex batch process industries. With the trend toward flexibility, many of the applications in the process industries share requirements traditionally thought to be exclusive to either DCS or PLC. Take the ice cream sandwich example. With several autonomous controllers, if a controller failed, it would impact only that process and not all of the others, which led to a robust system that virtually eliminated entire plant failure. In contrast, there are more programmers available for hire in the PLC arena and with the new programming languages such as function block, sequential function, etc., the advantage of function block programming is no longer exclusive to the DCS. It provides interface to connect thousands of sensors across wide region for various monitoring and controlling operations. Another major benefit of the DCS was the integrated monitoring and control system similar to today’s SCADA systems. Interestingly, this debate over the virtues of DCS vs. PLC has been ongoing since these two architectures came into existence 40 years ago. This is because a DCS normally has built-in redundancy, ensuring a higher level of system insurance. PLC Pros: 1. A DCS or distributed control system is similar to a PLC in that it has rugged computer controllers, however, the DCS contains multiple autonomous controllers that are distributed throughout a system, also used for automating processes. I hope all the above questions wont bother you much. What's the main difference between DCS & PLC? Your DCS is your captain. At Bedford, Morley and his friend wrote proposal after proposal, mostly for local tool firms hoping to evolve into the new solid state manufacturing arena with the help of small computers. Whereas in a DCS, asset management software provides alerts of what might break before it does, so a fitting substitution can be made. In addition, today's DCS hardware is not as expensive as it was a couple of decades ago and is less difficult to implement. The programming of the PLCs was primarily in ladder logic, a format very similar to a schematic. This is all about the Programmable Logic Controller aka PLC. The plant would have a production line for the ice cream, and one of the autonomous controllers would process the batch of ice cream. However, the latest generations of PLCs are increasingly capable of delivering simple to complex proportional integral derivative (PID) control. With open source communications, fiber optics, Ethernet and the like, many PLCs can now communicate with each other and behave as autonomous PLCs that communicate over the network to other autonomous controllers. As a utility player, PLCs are highly customisable. A wide range of control application. Game on. Here again the DCS has an advantage over a PLC. In those early days of automation, there was a clear spilt between DCS and PLC systems, with both types being designed for their specific tasks. The DCS was really good at autonomously controlling single or multiple processes. The speed of logic execution is another key differentiator between DCS and PLC. The proposals didn’t exactly meet Morley’s creative nature—they were so similar and repetitive that, being the antsy type, he eventually grew bored. 2. The benefits of a DCS are combined with the benefits of a PLC, without the disadvantages of both systems. That interface may do something like handling the manual and automatic operation of a valve. 5. An advantage of the DCS is installation costs. PLCs have a simpler architecture, as is evident from the diagrams above. As good fortune would have it, during the design phase of Morley’s creation, an executive at GM presented a request for a solid state controller that would make plants more reliable and durable, one that could also replace the hardwired and unreliable relay systems that were pervasive in manufacturing. However, the latest generations of PLCs are increasingly capable of delivering simple to complex proportional integral derivative (PID) control. One needs to weigh the system costs and the advantages/disadvantages to make the best decision for the situation at hand. Today, we will dive into some of the advantages of PLCs. Mark Proctor is managing director of industrial spares supplier EU Automation. Modicon was now in business, big time. Response times of one-tenth of a second make the PLC an ideal controller for near real-time actions such as a safety shutdown or firing control. A PLC can become a “sub-system” of a DCS when the application calls f… For instance, say you had a plant that made an ice cream-filled cookie sandwich. The big change in DCS over the past 20 years is its move from proprietary hardware to the personal computer (PC) and standard LAN technologies. On the other hand, PLCs evolved from solid state relays and, as opposed to DCS, were used where process restarts were not a major concern, but processing speed was important. The PLC was actually born more than forty years ago when an antsy design engineer named Dick Morley quit his job over a dispute with his boss (he wanted to work on Saturdays instead of Fridays, so he could ski more…his boss said no) and formed a company with a friend called Bedford Associates. Systems can be shut down for maintenance, troubleshooting or upgrades without damage to equipment or significant downtime costs. A Programmable logic controller(PLC) is simply a special purpose computing device designed for use in industrial control systems and other systems where the reliability of the system is high. 3. DCS designs often trade high levels of functionality for repeatability and dependability. About Bayt.com. Here we are comparing PLC with the relays and DCS (Distributed Control System). Tag: advantages of dcs over plc. As the price point of the DCS has come down, more manufacturers are looking at the advantages of DCSa architecture . However, DCSs do not need to be this quick because they control systems rather than individual devices. This advantage occurs because of the location of the autonomous controller to the process can be close in vicinity versus pulling long runs of I/O wire across a plant. An entire DCS is much more expensive than a few PLC’s, but each have their advantages in any given situation and certain automated systems will always require one over the other. Diagnostics in a PLC system will alert an engineer when something is broken. The DCS’ onboard monitoring and control system is also a plus. You can see that with today’s technologies, a wide and robust PLC system could do virtually the same thing that the DCS can do. A DCS is used when the value of the products manufactured is high, the production is continuous and failures in the system result in damage to process equipment - for example, if a glass kiln dropped below a certain temperature. It has great computational capabilities. Following are the benefits or advantages of SCADA: The system provide facility to store large amount of data. With a modular or subsystem architecture, you can add new equipment to a DCS all day long. Lean more about: PLC vs Relay system. A DCS typically covers an entire process, and is capable of covering an entire plant. In the early stages of design, the first priority is to define the project library of objects, such as valves. A DCS will be able to take advantage of all the aspects of an automated system, from the machines and sensors to the controllers and computers. 2 (original print article) gives a Venn-diagrammatic picture of the situation, which is still changing as PLC and DCS vendors adapt to "soft" PLC technology and "smart" bus-connected field devices. To receive our free weekly NewsBrief please enter your email address below: © Setform Limited 2019-2021 | Privacy policy | Archive. Mark Proctor is managing director of industrial spares supplier, FREE Subscription to Engineering magazines. One of the first and simplest advantages is reliability. In essence, some industrial plants are now employing more than one captain to ensure critical systems are well managed. The Benefits of DCS Using a DCS allows a plant’s engineering staff to supervise and manage a larger number of control loops and other similar plant components and processes. By Mondi Anderson, Controls Engineer at Metawater USA and Automation Instructor at RealPars In a nutshell, a PLC or programmable logic controller is a ruggedized computer used for automating processes. ... DCS stands for Distributed Control System and PLC stands for Programmable Logic Controller. PLCs are designed to meet the needs of applications that require scan rates of ten milliseconds or less. 1. 4. However, consumers willing to adopt automated robotics applications in their manufacturing processes still need to understand their differences. PLC (especially Compact PLC) has a lower cost associated with it as compared to the other automation technology. DCS took care of the delicate continuous processes like melting and conditioning control. Advantages of PLC over Relays: PLC increases the reliability, flexibility, and accuracy of the automation system. 4.If point 3 is convinced what are the advantage of PCS7 over other DCS like Honeywell ,Yokogawa etc.????? When designing a logic diagram using PLC or programming logic devices it has many advantages over the traditional wired logic some of the advantages besides a fast response time: 1- complex logic can be achieved using the same PLC unit. Most plant floor technicians are familiar with ladder logic programming however, DCS programmers and technicians typically need more specialized experience in database functions, as well as IT-related networking knowledge. The entire tag base is right there, already created for the process control, and available to use on the monitoring and control screens. PLC VS DCS . This is another myth. Demonstrating advantages ABB was able to offer CEE some examples to demonstrate how savings can be realised by using today’s DCS workflow, when compared with a PLC/HMI (SCADA) system. He wondered if he could create an automated programmable controller that could handle his clients’ everyday jobs. They have standard libraries and routines built in, but also have the capability to be specially programmed using custom code from scratch. There is no clear cut fast rule about when to use a PAC, PLC, or IPC. There were many benefits to the DCS, but one of the primary advantages was that an entire plant could be connected via proprietary communications and controlled by a distributed system. Like a good captain, the highest priority of a DCS is to deliver reliability and availability. a DCS and a PLC were well defined. A DCS takes much longer to process data, … Yet another controller might process the cookie batch, while another might supervise the baking process. There are some advantages of programmable logic controller (PLC) are given below, It has very faster scan time. Speaking of advantages, today’s PLC systems offer nearly the same ones as the DCS, excluding the supervisory control and data acquisition (SCADA). Modern industrial applications are demanding the reliability of a DCS system but the flexibility of a PLC. Do you know the Difference between DCS and PLC Systems ? The first name on the team sheet, your DCS is dependable, hardworking and controls the whole outfit. This saves in development time when programming a PLC. They were initially developed to replace hardwired relays, sequences and timers used in the manufacturing process by the automation industry, but today they have scaled and are being used by all kind of manufacturing processes including robot based lines. The RealPars team at: mondi.anderson @ gmail.com, or IPC control.... Eu automation provide facility to store large amount of data the scarcity of programmers have! Captain, the PLC was used primarily for discrete controls 35 years ago that the first on. Entire plant facility with parts of your process strewn throughout, then a typically! 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