are connected to controllers, which are connected to the process DCS backbone. These interfaced subsystems generally require more field engineering to configure and maintain than the other plant controls. If the vendor tells you this can only be done by taking a training course on their product, don’t walk…run away from this supplier. The need to connect to multiple industrial networks is a necessity and virtually all process plants utilize multiple discrete and process industrial networks including DeviceNet, Profibus, PROFINET, EtherNet/IP, Modbus TCP, HART, and Foundation Fieldbus. As part of this process you might think about how open architectures have changed the game. DCS is mainly used as a control system and will feature different processes which can be made up of merged PLC’s. The controls and automation on a skid become part of the plant just as much as site installed controls and automation. Your DCS is your captain. This distinction between the DCS and SIS, led to separate markets for both types of systems with separate suppliers for both, initially. For example, if you have a two input, one output valve, there is a function block library so you don’t have to create the logic from scratch. In a nutshell, a PLC or programmable logic controller is a ruggedized computer used for automating processes. PLCs are adding these functions with their push into process control. The idea of using a PLC-based system rather than a Distributed Control Systems (DCS) has become a philosophical and technical debate in the industry. You might want to try your own search, though. The PLC was invented in response to the needs of the American automotive manufacturing industry primarily to replace thousands of relays, cam timers, and drum sequencers. Following this logic, the decision is between the new PLC-based DCS and traditional DCS offerings. This level of optimization is high level, multivariable control based on real-time business management goals, actual feedstock information, production demand, and energy costs - all in an effort to optimize plant profits. PLC-based control systems began to function like a mini-DCS. ... 3 Comments on “ The Difference Between PLCs and Computers ” Richard says: January 28, … 1. There are plants where PLCs or DCSs control all of the plant functions but at this point these are the exceptions. Does the system reduce engineering time for my applications? turn the clock back 10 years: The programmable logic controller (PLC) is king of machine control while the distributed control system (DCS) dominates process control. The system realizes the function and coordination of any device, and the PLC device only realizes the functions of … The function or intent of traditional PLCs was to provide a stand-alone control system that was economical and very efficient at processing various I/O types. DCS systems have for many years provided multi-disciplined controllers for logic, sequential and process control, HMIs, custom applications, and business integration on one platform. This feature we can not achieved in PLC. These days, there is probably no single factory in the word that d… DCSs have been the primary solution for process automation but now many PLC vendors are arguing that a single integrated architecture based on PLCs and/or PACs is the best approach to total plant automation. Programmable Logic Controller (PLC) also known as Industrial Computer is the major component in the industrial automation sector. ifference between PLC,DCS & SCADAIn the past the strength and weakness of both the automation technologies were well understood. Joined: 9/27/2006. Asset management is becoming more important and PLCs are playing catch up with DCSs to provide integrated software for a full range of devices and asset management standards. What is a PLC? Today with open technologies, DCS systems are competitively priced with PLCs. He responded by rephrasing the question, noting the real question should be what distinguishes their PLC-based DCS from other DCS systems. The dilemma is that many skid vendors have typically standardized on one brand and model of PLC controller and the plant is using another vendor. Using same data base server you can edit in logic as well as on graphics screen. This included primarily digital I/O (On/Off) and analog I/O (continuous measurement). The first name on the team sheet, your DCS is dependable, hardworking and controls the whole outfit. For example, a historian may be added to many PLC products by plugging a module into the backplane that acquires data from the controllers, but history communications is done over a separate Ethernet connection. WTWH Media LLC and its licensors. Does the system support the enterprise software interfaces I need now? The difference between distributed control systems (DCSs) and programmable logic controllers (PLCs) can be boiled down to a simple football metaphor. If you manufacture plastic widgets, you speak PLC. of I/O, then PLC is better from cost view. DCS and PLC have been pillar for control of process plant for quite some time now with advancement in technology. In this article the term PLC will include PAC. Major worthy advantage of DCS is having centralised database server. At the same time, the DCS hybridized to incorporate PLCs and PCs to control certain functions and to provide reporting services. These PLC vendors are continually demonstrating how their software is like a DCS. DCS backbone networks are typically standard Ethernet hardware but use their own closed,high-performance protocols and natively support redundancy. The time and cost of integration is significant over the life of a system and should be examined as part of the analysis. The everyday use of our smart phones, iPads, and electronic games decreases the cost of increased computing power. Process optimization is another area where traditional PLCs may be lacking when compared to a DCS, which will typically offer a number of tools for optimizing control loops and more advanced alternatives to improve performance of PID control. This distributed architecture was revolutionary with digital communication between distributed controllers, workstations and other computing elements. 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. Does the system support the industrial network interfaces I need now and in the future? Real-time software modeling and control optimization is an emerging function being provided to achieve higher efficiencies by DCS suppliers. Many agree that the beginning of the DCS started with the introduction of the Honeywell TDC 2000 in 1975. of I/O with less cost. The PLC control and DCS control system is not a logical level concept. Difference Between PLC & DCS Cont…  Generally, PLCs are stand alone and perform a particular task, where a DCS is a network of PLCs that communicate in some … Skid mounted and packaged systems are factory built units that provide a specific function needed in a plant. The DCS from its inception has been designed for configuration as opposed to PLCs which started with a general programming model. Protocols, like OPC, have eased interactions between the two control systems. Typically, their interfaced … DCS is mainly used to handle anolog IO's and PLC's for digitaly . C'mon over to https://realpars.com where you can learn PLC programming faster and easier than you ever thought possible! it's cost is lower than compare to PLC and DCS, it uses profibus and modbus as a communication protocol which are very speedy responds. PLC suppliers have been developing new configuration software to provide this level of integration. In turn, there are DCS vendors that have introduced PLC and PAC products as offerings. Advantage DCS. Before we get into the differences of a PLC’s and DCS’s, we need to talk about what each of them are designed to do. PLC specialist Mart n Hilbers talks about the differences between a PLC-SCADA control system and a DCS configuration. It sure looks like the PLC vendors who advocate a single control architecture for process plants are essentially creating a DCS system built around their hardware and software components. Ten years ago there was a marked difference in the cost of technologies used in DCS controllers and PLCs but with processors, memory, embedded software, and communications commoditization, this has become insignificant for new offerings from all vendors. also DCS comes with it's SCADA always. Does the system reduce process control configuration time? If you produce chemicals, you speak DCS. As this unfolds, both DCS and PLC suppliers will evolve and we may eventually see a new architecture but in the meantime plants need to continue to operate and improve. Rating: (2169) Hello Viana; I would say: Less and less difference every day, now. ... PLCs may also take the form of a computer or a small single module. DCS is dealing with very large no. What’s difference between PLC and DCS by its definition: PLC is a controller or processor that can be programmed (programmable) whose function is to run (execute) logic functions. This is driven by increased unit volume production of processors and related components. The premise is this offers the best of both worlds. I have never understood how engineers that would never buy a new automobile without looking under the hood and taking test drives will buy an automation system based on vendor demonstrations and PowerPoint presentations. Last visit: 1/7/2021. 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. When configuring a tag, everything required is there to connect it to a field point and apply alarm logic, history, version control and other functions, saving time and improving quality. As you can see, there are a lot of similarities between the two systems. PLC systems use open published protocols that are designed to cover a wide range of applications including simple discrete, synchronized motion control, motor control, and process. The DCSs generally control and manage the core processes (food, pharmaceutical, refining, etc.). Difference between PLC & DCS:- To perform advanced regulative management on a plant-wide scale, DCSs contain the integral infrastructure.Slower processes usually need coordination across varied production units. But as far as concern about the functionlity of DCs and PLC both are same. DCS, or Data Control System, is process oriented, as it focuses more on the processes in each step of the operation. In DCS systems, the process networks (Foundation Fieldbus, HART) and PLC-oriented networks (DeviceNet, Profibus, Modbus, etc.) Superior speed makes PLCs a much better alternative for applications involving quick production startup mistreatment distinct I/O. It was the first system to use microprocessors to perform direct digital control of processes as an integrated part of the system. "re: difference between plc,dcs&scada" This has been discussed several times, but when I did a search on the site I couldn't locate the threads. Concerned about safety? To sum up this post, the difference between the PLC and SCADA is as follows. Most systems can answer yes to these questions, so you need to quantify these characteristics to make solid decisions. 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. An advantage often cited by PLC vendors is that all control functions can connect to one Ethernet backbone (process control, discrete, motion control, safety; etc.) DCSs were traditionally used to control large processes, while PLC systems were used to control machines. Well, I think DCS - Distributed Control Systems - is a control device that has higher capabilities compared to an ordinary PLC. (SAP, Oracle, etc.). PLC is mainly used as a controller of processes and mainly comes as a standalone program. Accomplishing this with PLC-based systems at this time can be approximated with loosely coupled software add-ons. DCS is a relatively large system while the PLC is a small system. Currently there are two main stream types of control systems – PLC-SCADA and Distributed Control Systems (DCS). The DCS supervises the entire process, much like the conductor in an orchestra. Oddly the discrete network interfaces can be an issue with PLC systems since there are many standards and larger vendors optimize the interface and software configuration to their flagship protocols and have weak interfaces to competitive protocols. I understand that the gap in technical capabilities between these 2 breeds of process control systems have narrowed, but still I understand there are some fundamental differences … In my opinion, this is not a rational engineering approach when configuring plant systems for performance and reliability. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media. Need an open communication architecture? DCS versus PLC. The big advantage was that programmable logic controllers could be reconfigured with software programming rather than rewiring control panels. 1) DCS are designed or made available to the user in a way that only configuration in form of a Functional Block has to be carried out unlike PLC, where complete programming has to be implemented using any one of the different languages available in the system. A DCS is likely to be more reliable as well, ensuring the continuous operation of a process or system. Slower processes usually need coordination across varied production units. Consider that mobile phone shipments in 2010 were 1.39 billion, up 18.5% from the 1.17 billion units shipped in 2009. This investment upfront can save a large amount of money and lost production time over the life of a system. LINAK launches the world’s first electric linear actuator with IO-Link. Many process control systems require redundancy for I/O, controllers, networks, and HMI servers at various levels. The majority of process plants today have both DCSs and PLCs installed for controls. Since the PLC was integrated with Analog I/O it crosses the boundary of being just digital and crosses to the realm of DCS in handling Analogs, Bus Systems, Distributed I/O and etc. Integration with the enterprise is becoming very important to improve operations and maximize asset management. For instance, PLCs are faster and can handle more complex control. DCS is a kind of Distributed Control System, and PLC is just a (programmable logic controller) controlling “device”, the two are the difference between “system” and “device”. Logic means the discrete / sequence function is usually handled by the relay. It means PLC is a sub system of a large system called DCS. if DCS stopped, all system is stopped. Advantage SCADA. At the time they were introduced (in the late '70s, and 1980s) DCS (Distributed Control Systems) were developped for continuous or batch process control of large processes: rafineries, steel mills, and such. The level of controller redundancy for higher level process applications is new to PLC suppliers and they continue to add options for redundancy. DDC : DDC is a universal controller where both analog and digital input/outputs are combined in one controller card also it is specially designed for the HVAC ( Heat ventilation air conditioning) design which are used for air handling unit. I suggest, rather than accepting a suppliers definition of a single unified architecture, that you create a definition for your operations. Ideally the plant process control system has efficient and cost effective multiprotocol interfaces for all PLC protocols. The main difference between Programmable Logic Controller (PLC) and Distributed Control System (DCS) are: The number of I/O in the system. PLCs were originally designed to replace relay control systems and their low relevant cost made them ideally suited for production automation and machinery. A PLC is a digital computer used to control electromechanical processes, usually in an industrial environment. In principle, PLC can form DCS. Does the system support interfaces to my legacy systems. So it was easy for engineers to select the one that suits their application, but now due to the advent of microprocessors both the technologies are merging.The requirements which are thought to be exclusive to one technology can be found in the other one … These other protocol interfaces are typically accomplished with third party interfaces where the software configuration is more cumbersome. 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. I suggest having your own control engineer(s) configure some control loops, sensors, I/O configuration, HMI screens, and communications – specific to your applications - for each system under consideration. Although PLCs have become more powerful, they are still based on “loose” component architectures allowing functions to be easily added with hardware and software. It can be seen from the name: PLC is named after function, and DCS is named after architecture. The automotive industry is still one of the largest users of PLCs. Either way, you go, hopefully, this article has shed some light on both the similarities and differences between … The most significant difference between the two is their general design. Difference Between PLC & DCS Difference between PLC & DCS :- To perform advanced regulative management on a plant-wide scale, DCSs contain the integral infrastructure. SCADA is a system that relies on computers, software and communication media to remotely monitor and control devices in a control system, usually large-scale. All rights reserved. DCS systems generally have easier to apply redundancy solutions but the open networking standard groups such as ODVA and PI International have defined solutions for their protocols particularly with the initiatives for networked machine safety. Posts: 10313. Bosch Rexroth precision modules meet requirements for clean production, Precise miniature slide guides from NB Corporation, The top 10 linear motion articles of 2020, Identifying Best-Value Linear Motion Technologies, Learn how to reduce noise and distortion in encoders’ signals, Helical Planetary Gearboxes: Understanding The Tradeoffs, Tweets from https://twitter.com/Motion_Control/lists/motion-control-tweets. Computer-based process control systems before the TDC 2000 were mainly data collection and alarm systems with controlled done by pneumatic loop controllers and standalone electronic PID controllers. The idea of using a PLC-based system rather than a DCS has become a philosophical and technical debate in the industry. PLCs on skid mounted and packaged systems for process plants are creating control and automation problems. 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. However, with more powerful PLCs and so-called programmable automation controllers or PACs available today, the line between a PLC and DCS continue to blur. if the system has less No. When is encoder resolution specified in bits, and what does that tell us? PLCs are used to control non-core process functions including material handling, water treatment, motor controls, balance of plant operations, air compressor controls, packaging, and other functions. This can be accomplished with a demonstration system provided by vendors, including controller hardware. Selecting the right system for your operations requires complex analysis, with a number of considerations, based on production processes, in-house capabilities, and other factors. One thing is clear, process users are getting more options to consider. Distributed Control Systems (DCS) have been the primary solution for process automation but now many PLC vendors are pursuing these applications arguing that a single integrated architecture based on PLCs and/or PACs (Programmable Automation Controllers) is the best approach to total plant automation. Now a days you cannot really tell the difference between a PLC or a DCS. Both DCS and PLC can be configured or reconfigured. Of course, the difference in performance between … In an interview early in 2011 with a business manager at a major PLC company who is pursuing the process business, I asked what distinguishes their offering from a DCS. The primary logic offered for using a single PLC-based system rather than a DCS for process functions along with PLCs for discrete functions is to have one control architecture for the entire plant. 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New to PLC suppliers and they continue to difference between plc and dcs in tabular form options for redundancy installed controls and automation PLC. Tdc 2000 in 1975 users of PLCs integrated part of the system support the industrial interfaces...