{"id":46801,"date":"2020-01-24T10:35:37","date_gmt":"2020-01-24T05:05:37","guid":{"rendered":"https:\/\/ye1o34zhk8.onrocket.site\/?p=46801"},"modified":"2022-09-28T14:40:32","modified_gmt":"2022-09-28T09:10:32","slug":"dcs-system-layout","status":"publish","type":"post","link":"https:\/\/instrumentationtools.com\/dcs-system-layout\/","title":{"rendered":"DCS System Layout and its Different Parts"},"content":{"rendered":"

In this article, we discuss the topic on different parts of DCS system layout<\/strong> and its modules like processors & IO cards, marshalling & system cabinets, engineering & operator workstations, and Switch.<\/p>\n

Distributed Control Systems (DCS)<\/strong> plays a vital role in manufacturing, production industries as they are used to control and manage the processes.<\/p>\n

\"DCS<\/p>\n

Image Courtesy: manufacturingchemist<\/a><\/p>\n

Distributed Control Systems are extension of traditional controllers. The major concept of distributed control systems application is derived from the idea of decentralizing the control unit and establishing a common network between the operator, engineering stations.<\/p>\n

DCS tends to be used on large continuous process plants where high reliability and security is important, and the control room is not geographically remote.<\/p>\n

DCSs are connected to sensors and actuators and use set point control to control the flow of material through the plant.<\/p>\n

Read:<\/strong> DCS Tutorial<\/a><\/p>\n

Although 4\u201320 mA has been the main field signalling standard, modern DCS systems can also support field bus digital protocols, such as Foundation Fieldbus, profibus, HART, Modbus, PC Link, etc., and other digital communication protocols such as modbus.<\/p>\n

DCS System Layout<\/h2>\n

\"DCS<\/p>\n

DCS System –\u00a0 Level 0<\/h3>\n

This level contains the field devices such as flow and temperature sensors, and final control elements, such as control valves.<\/p>\n

DCS System –\u00a0 Level 1<\/h3>\n

This level contains the marshalling cabinets where the field termination takes place. Also houses the intrinsic safety barriers, relays, Terminal blocks, Isolators etc. from here the signal travels from the Junction boxes wherein the signals are paired and received from the appropriate sections in the field area.<\/p>\n

DCS System – Level 2<\/h3>\n

This level contains the system cabinet which is designed to accormodate power supply,controller and I\/O cards. The field signals will be digitally processed by the I\/o cards and sent to the controller for further digital processing.<\/p>\n

This part will be located in the top most part of the cabint and will be brain of the automatic system.<\/p>\n

DCS System – Level 3<\/h3>\n

This level consists of visual disply unit or computer, is the operator interface. It is production control level, which directly control the process. Plant operational schematics are displayed. Alarm and interlock cause and effect diagrams are displayed in different pages.<\/p>\n

Read:<\/strong> Types of System Architecture<\/a><\/p>\n

System Cabinets<\/h2>\n

In system cabinet, all electronic modules will be installed like processor cards (CPU), input modules, output modules, serial communication cards, power supply modules, rack to rack inter-communiacation modules, fieldbus cards, profibus cards, modbus cards.<\/p>\n

\"DCS<\/p>\n

Main types of input modules are analog input (AI) cards, digital input (DI) cards. The number of IO channels will vary depends on the user selection of these cards like 8 channel, 12 channel, 16 channel & 32 channel.<\/p>\n

Similarly output modules are analog output (AO) cards, digital output (DO) cards.<\/p>\n

Marshalling Cabinets<\/h2>\n

Marshalling cabinets<\/a> shall be used to terminate all field cables as well as for grouping of various signals from the field devices properly tagged.<\/p>\n

\"DCS<\/p>\n

Sometimes different marshalling cabinets can be allocated based on type of signals like analog input\/output signals, digital inputs, digital output and relays.<\/p>\n

Operator WorkStation<\/h2>\n

The\u00a0operator workstations\u00a0are used for monitoring all system operations and for effecting control actions and parameter adjustments.<\/p>\n

There are normally multiple operator workstations, as illustrated in\u00a0above figure, each of which contains all of the process graphic displays and historical trend displays for the system.<\/p>\n

Some of the operations performed through the Operator workstations are listed below;<\/p>\n