Distributed Control Systems, DCS. • Individual Controllers communicating to a central computers acting as workstations. • Communication accomplished by. A distributed control system (DCS) is a computerised control system for a process or plant .. Print/export. Create a book · Download as PDF · Printable version. Distributed control systems (DCSs) are computer-software packages communicating with control hardware and providing a centralized human– machine.
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PDF | This paper addresses intelligent communication among device entities to solve aspects of the Distributed Control System (DCS) for process control in an . Distributed control system used to control complex distributed industrial functions. Find about 4 basic elements and 7 features. Have a basic knowledge of, and be able to define, what a Distributed. Control System is. ➢ Understand the general benefits of Distributed Control Systems.
It gives greater flexibility to control distributed discrete field devices and its operating stations In this era of revolution technology, industrial automation system deals with advanced automation control technologies to have better control performance over complex processes. Distributed Control System To increase reliability, productivity and quality while minimizing the production cost, process control industries must be driven by integrated controllers with high distributed control capability.
What is Distributed Control System Distributed Control System is a specially designed control system used to control complex, large and geographically distributed applications in industrial processes. In this, controllers are distributed throughout the entire plant area. These distributed controllers are connected to both field devices and operating PCs through high speed communication networks as shown in figure.
Discrete Field devices such as sensors and actuators are directly connected to input and output controller modules through communication bus. DCS Architecture Controllers are distributed geographically in various section of control area and are connected to operating and engineering stations which are used for data monitoring, data logging, alarming and controlling purpose via another high speed communication bus.
DCS provides information to multiple displays for user interface. It also facilitates to variable set points and opening and closing of valves for manual control by the operator. Its human machine interface HMI , face plates and trend display gives the effective monitoring of industrial processes. Elements of DCS Engineering PC or controller This controller is the supervisory controller over all the distributed processing controllers. Control algorithms and configuration of various devices are executed in this controller.
Network communication between processing and engineering PC can be implemented by simplex or redundant configurations. Distributed controller or Local control unit It can be placed near to field devices sensors and actuators or certain location where these field devices are connected via communication link.
Availability of a fully functional graphical user interface was a way away. Central to the DCS model was the inclusion of control function blocks. One of the first embodiments of object-oriented software, function blocks were self-contained "blocks" of code that emulated analog hardware control components and performed tasks that were essential to process control, such as execution of PID algorithms.
Function blocks continue to endure as the predominant method of control for DCS suppliers, and are supported by key technologies such as Foundation Fieldbus  today. Midac Systems, of Sydney, Australia, developed an objected-oriented distributed direct digital control system in The central system ran 11 microprocessors sharing tasks and common memory and connected to a serial communication network of distributed controllers each running two Z80s.
The system was installed at the University of Melbourne. Digital communication between distributed controllers, workstations and other computing elements peer to peer access was one of the primary advantages of the DCS. Attention was duly focused on the networks, which provided the all-important lines of communication that, for process applications, had to incorporate specific functions such as determinism and redundancy.
As a result, many suppliers embraced the IEEE This decision set the stage for the wave of migrations necessary when information technology moved into process automation and IEEE In the s, users began to look at DCSs as more than just basic process control. The system installed at the University of Melbourne used a serial communications network, connecting campus buildings back to a control room "front end".
Each remote unit ran two Z80 microprocessors, while the front end ran eleven Z80s in a parallel processing configuration with paged common memory to share tasks and that could run up to 20, concurrent control objects. It was believed that if openness could be achieved and greater amounts of data could be shared throughout the enterprise that even greater things could be achieved.
The first attempts to increase the openness of DCSs resulted in the adoption of the predominant operating system of the day: As a result, suppliers also began to adopt Ethernet-based networks with their own proprietary protocol layers. Plant-wide historians also emerged to capitalize on the extended reach of automation systems. The drive toward openness in the s gained momentum through the s with the increased adoption of commercial off-the-shelf COTS components and IT standards.
Probably the biggest transition undertaken during this time was the move from the UNIX operating system to the Windows environment.
While the realm of the real time operating system RTOS for control applications remains dominated by real time commercial variants of UNIX or proprietary operating systems, everything above real-time control has made the transition to Windows. The introduction of Microsoft at the desktop and server layers resulted in the development of technologies such as OLE for process control OPC , which is now a de facto industry connectivity standard.
The s were also known for the "Fieldbus Wars", where rival organizations competed to define what would become the IEC fieldbus standard for digital communication with field instrumentation instead of 4—20 milliamp analog communications.
The first fieldbus installations occurred in the s. Fieldbus technics have been used to integrate machine, drives, quality and condition monitoring applications to one DCS with Valmet DNA system.
The impact of COTS, however, was most pronounced at the hardware layer. The initial proliferation of DCSs required the installation of prodigious amounts of this hardware, most of it manufactured from the bottom up by DCS suppliers. Standard computer components from manufacturers such as Intel and Motorola, however, made it cost prohibitive for DCS suppliers to continue making their own components, workstations, and networking hardware.
As the suppliers made the transition to COTS components, they also discovered that the hardware market was shrinking fast. COTS not only resulted in lower manufacturing costs for the supplier, but also steadily decreasing prices for the end users, who were also becoming increasingly vocal over what they perceived to be unduly high hardware costs. The gaps among the various systems remain at the areas such as: While it is expected the cost ratio is relatively the same the more powerful the systems are, the more expensive they will be , the reality of the automation business is often operating strategically case by case.
The current next evolution step is called Collaborative Process Automation Systems.
DCS design offers perfect secured system to handle system functions for better factory automation control. Security is also provided at different levels such as engineer level, entrepreneur level, operator level, etc. DCS system can be implemented in a simple application like load management using network of microcontrollers.
Here the input is given from a keypad to a microcontroller, which communicates with the other two microcontrollers. One of the microcontrollers is used to display the status of the process as well as the loads, while the other microcontroller controls the relay driver.
The relay driver in turn drives the relay to operate the load. Hope you have understood the concept of distributed control system and its importance. Here is a basic question for you — Give any application of a DCS, you are aware of. Please share your ideas and suggestions about this article in the comment section below.
Many DCSs could cause personal loss of life or injury. A petroleum refinery is a good example of a safety-critical plant. In such an environment, a control system governs flares that constantly burn gas. If the control system fails and the flares cease burning, gas collects, and pools, causing an extremely dangerous situation. DCSs aim to centralize plant operations to allow control, monitoring, and reporting of individual components and processes at a single location.
Hi Prince Jan C. Albarracin Thank you very much for telling me how much you have enjoyed reading my column And once again please visit our International website https: Hi Prajapati Darpan Okay we will try and Thank you very much for telling me how much you have enjoyed reading my column And once again please visit our domestic website https: Hi Sasenthiran please visit our domestic website https: Hi Thank you so much for your feedback And once again please visit our domestic website https: But in process industries, no of IO are in thousands so plc is not able to handle such a large control system or PLC is not able to scan data faster.
So Distributed Control System used as Master where so many plc and controller with a different protocol and complex networking are controlled by DCS with maximum redundancy and optimization. Best Regards.
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Leave this field empty. It gives greater flexibility to control distributed discrete field devices and its operating stations In this era of revolution technology, industrial automation system deals with advanced automation control technologies to have better control performance over complex processes.