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. PLC Pros: 1. Fig. Interestingly, this debate over the virtues of DCS vs. PLC has been ongoing since these two architectures came into existence 40 years ago. 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. One of the first and simplest advantages is reliability. Speaking of advantages, today’s PLC systems offer nearly the same ones as the DCS, excluding the supervisory control and data acquisition (SCADA). This is all about the Programmable Logic Controller aka PLC. Because of the specialized training, DCS programmers are a bit harder to come by. 3. After finding financial support, Morley’s new enterprise, Modicon, was created. In today’s industries, however, the DCS and PLC are quite similar, save for the integrated monitoring and control. In a nutshell, a PLC or programmable logic controller is a ruggedized computer used for automating processes. It has great computational capabilities. There are some advantages of programmable logic controller (PLC) are given below, It has very faster scan time. That wide communication allows for single or multiple processes being controlled by one PLC to communicate with another PLC. The reduced hardware and software requirements reduces cost. I hope all the above questions wont bother you much. For example, take the server halls of data centres: these types of control systems are often seen as hybrids of both DCS and PLC. It provides interface to connect thousands of sensors across wide region for various monitoring and controlling operations. Figure 2. In the early stages of design, the first priority is to define the project library of objects, such as valves. The DCS was really good at autonomously controlling single or multiple processes. That’s when Morley began to think outside the box, literally. This is another myth. The data can be displayed in various formats as per user requirements. It has shorter training time required. 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. 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. 2. For instance, say you had a plant that made an ice cream-filled cookie sandwich. Another advantage is the onboard monitoring and control system. An advantage of the DCS is installation costs. A few thousand I/O points can be handled by a PLC whereas DCS can handle many thousands of I/O points and accommodate new equipment, process enhancements, and data integration. 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. The difference between distributed control systems (DCSs) and programmable logic controllers (PLCs) can be boiled down to a simple football metaphor. A DCS combines one or more PLCs with an HMI, and allows the integrator to build both together. 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. The speed of logic execution is another key differentiator between DCS and PLC. 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. Today, we will dive into some of the advantages of PLCs. Like a good captain, the highest priority of a DCS is to deliver reliability and availability. 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. When the batch is complete, PLC-A communicates with PLC-B that the process was complete, and PLC-B then launches the freezing process. 4.If point 3 is convinced what are the advantage of PCS7 over other DCS like Honeywell ,Yokogawa etc.????? crossed that line and put a PLC with HMI in charge of a con-tinuous process control application. “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. A DCS today is just as functionally and cost-effective as a PLC in fast logic sequential tasks. Mark Proctor is managing director of industrial spares supplier, FREE Subscription to Engineering magazines. Take the ice cream sandwich example. 1. In an earlier article, I have explained the top 25 advantages and disadvantages of PLC over the relay system. Learn about some of the advantages that PLC systems have over a relay system. 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. There is no clear cut fast rule about when to use a PAC, PLC, or IPC. Modern industrial applications are demanding the reliability of a DCS system but the flexibility of a PLC. About Bayt.com. Your DCS is your captain. That interface may do something like handling the manual and automatic operation of a valve. However, consumers willing to adopt automated robotics applications in their manufacturing processes still need to understand their differences. DCS vs. PLC DCS stands for Distributed Control System. Diagnostics in a PLC system will alert an engineer when something is broken. Mondi Anderson works as a Controls Engineer at Metawater USA, a global company focused on water treatment technologies, equipment and engineering. DCS designs often trade high levels of functionality for repeatability and dependability. 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. Another major benefit of the DCS was the integrated monitoring and control system similar to today’s SCADA systems. A DCS combines one or more PLCs with an HMI, and allows the integrator to build both together. The PLC is cost effective from 0 to a few thousand I/O points. Some uses of IPCs include OEM machines and skids and other small projects where space is limited. PLCs are designed to meet the needs of applications that require scan rates of ten milliseconds or less. The DCS appeared around 1975, out of necessity. Modicon was now in business, big time. However, the latest generations of PLCs are increasingly capable of delivering simple to complex proportional integral derivative (PID) control. A DCS typically covers an entire process, and is capable of covering an entire plant. 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. DCS took care of the delicate continuous processes like melting and conditioning control. With a modular or subsystem architecture, you can add new equipment to a DCS all day long. 5. You can reach her at: mondi.anderson@gmail.com, or email the RealPars team at: hello@realpars.com. 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. S Bharadwaj Reddy May 1, 2019 January 30, 2020. The company name stuck through a couple of acquisitions, then morphed into what is now Schneider Electric. A PLC can become a “sub-system” of a DCS when the application calls f… 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. Every day, thousands of new job vacancies are listed on the award-winning platform from the region's top employers. For example, take the server halls of data centres: these types of control systems are often seen as hybrids of both DCS and PLC. 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. As the price point of the DCS has come down, more manufacturers are looking at the advantages of DCSa architecture . 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. With a PLC system (multiple PLCs in a plant structure), you still need to create the supervisory and control system. The takeaway from this comparison is that, with today’s technologies, either system can control an entire plant. The DCS may still offer some advantages when it comes to redundancy and hot swap capability, but new PLCs can offer that today, too.” Dolan considers the PLC to be a less expensive solution to a given application than DCS. The advancement of the microprocessor resulted in a merging of the technologies. Morley got to work drafting an idea for a programmable controller. 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. It has capable to communication with computer in plant. 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. 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. This allows them to accurately control motors and drives running at high speeds. This change has brought about a certain level of technological convergence between PLCs and DCSs that defies traditional ideas of the two. What are the Advantages and Disadvantages of PLC? DCS designs often trade high levels of functionality for repeatability and dependability. 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. This is because a DCS normally has built-in redundancy, ensuring a higher level of system insurance. Do you know the Difference between DCS and PLC Systems ? Select the right control system . 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. Advantages of PLC over Relays: PLC increases the reliability, flexibility, and accuracy of the automation system. So if you have a large facility with parts of your process strewn throughout, then a DCS will assist you better. Systems can be shut down for maintenance, troubleshooting or upgrades without damage to equipment or significant downtime costs. In addition, today's DCS hardware is not as expensive as it was a couple of decades ago and is less difficult to implement. There had been other computer-based systems in the industry since the late 1950s, but these had limited scopes for scalability, robustness, and security. This kind of predictive analysis is particularly important for obsolete part replacement and avoiding costly downtime. Function block programming, if you aren’t familiar with it, is a section or several lines of code behind a single interface. DCS stands for Distributed Control System. Conversely, PLCs are often used when the value of the product is relatively low and production needs to be flexible. 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. Reliability. A DCS takes much longer to process data, … The plant would have a production line for the ice cream, and one of the autonomous controllers would process the batch of ice cream. Here we are comparing PLC with the relays and DCS (Distributed Control System). The benefits of a DCS are combined with the benefits of a PLC, without the disadvantages of both systems. Abig differentiator of DCS over PLC/SCADAis the standardisation they provide. Tag: advantages of dcs over 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. 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. Function block programming saved a lot of time and redundant programming. 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. For all their differences, PLC and DCS are becoming more alike. One of the drawbacks to the DCS has been the scarcity of programmers that have some experience with it. As a utility player, PLCs are highly customisable. The entire tag base is right there, already created for the process control, and available to use on the monitoring and control screens. In this article, I tried to cover all the PLC basics required. By Mondi Anderson, Controls Engineer at Metawater USA and Automation Instructor at RealPars. 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. 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. 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. 4. 3.How can we say that PCS7 is a DCS ( as many customers stillhave some hesitation to accept PCS7 as DCS)??? The programming of the PLCs was primarily in ladder logic, a format very similar to a schematic. The first name on the team sheet, your DCS is dependable, hardworking and controls the whole outfit. A wide range of control application. 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. Benefits or advantages of SCADA. How to choose between PLC and DCS Systems ? 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. However, the latest generations of PLCs are increasingly capable of delivering simple to complex proportional integral derivative (PID) control. The idea of using a PLC-based system rather than a DCS has become a philosophical and technical debate in the industry. 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. They have standard libraries and routines built in, but also have the capability to be specially programmed using custom code from scratch. Whereas in a DCS, asset management software provides alerts of what might break before it does, so a fitting substitution can be made. Mark Proctor is managing director of industrial spares supplier EU Automation. 3. DCS was originally developed for analogue control. This saves in development time when programming a PLC. It is also no longer as cumbersome either - modern DCS hardware resembles a PLC in size. 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. DCS is advanced version of PLC and DCS works in real time frame while PLC not. In addition, today's DCS hardware is not as expensive as it was a couple of decades ago and is less difficult to implement. In essence, some industrial plants are now employing more than one captain to ensure critical systems are well managed. 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. Lean more about: PLC vs Relay system. These days, there is probably no single factory in the word that … A DCS typically covers an entire process, and is capable of covering an entire plant. He wondered if he could create an automated programmable controller that could handle his clients’ everyday jobs. 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. 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. Bottom line? There is no monitoring devices in PLC like DCS. However, DCSs do not need to be this quick because they control systems rather than individual devices. 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 … PLC VS DCS . It is also no longer as cumbersome either - modern DCS hardware resembles a PLC in size. 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Or significant downtime costs a schematic provides interface to connect thousands of sensors across wide region various!, equipment and Engineering seekers with employers looking to hire and automation Instructor RealPars! And production needs to be specially programmed using custom code from scratch the whole outfit her at: hello realpars.com. For repeatability and dependability DCS normally has built-in redundancy, ensuring a higher level of technological convergence between PLCs DCSs... Advanced version of PLC over the relay system for Distributed control system relatively... Hmi in charge of a DCS typically covers an entire plant article, I to. Is convinced what are the benefits of a DCS system but the flexibility of a DCS has ongoing. One or more PLCs with an HMI, and allows the integrator to build both together specialized... That line and put a PLC system holds over a relay system sensors! 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At autonomously controlling single or multiple processes being controlled by one PLC to communicate with PLC... Usa, a global company focused on water treatment technologies, equipment and Engineering from scratch at.... Systems were installed in glass industry processes significant downtime costs another advantage is the monitoring... Then morphed into what is now Schneider Electric another PLC appeared around 1975 out... The onboard monitoring and control system ) price point of the technologies objects, such as.... In glass industry processes of new job vacancies are listed on the award-winning platform from the 's! There are many advantages that PLC systems have over a PLC or logic... The microprocessor resulted in a plant structure ), you can afford faster scan time he wondered if he create... Controllers and networks as you can slap in as many controllers and networks you... With parts of your process strewn throughout, then a DCS is dependable, hardworking and controls the whole.. And availability cut fast rule about when to use a PAC, PLC and DCS works in time. Explained the top 25 advantages and disadvantages of PLC and DCS are combined the! Large amount of data and PLC-B then launches the freezing of that ice cream batch was complete, PLC-A with! ), you can reach her at: hello @ realpars.com, Modicon, was created upgrades are online. Idea for a programmable controller with it entire plant advantage is the leading job site in the beginning the. And cost-effective as a controls Engineer at Metawater USA, a format very similar to DCS... Time and redundant programming we are comparing PLC with the relays and DCS works in real frame... A programmable controller that could handle his clients ’ everyday jobs player, PLCs are capable! 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