Distributed Control System

The Next Era of Factory Automation

[ Narrendar.R.C – 12MMT0007 ]

[ G.N.Abhilash – 12MMT0026 ]

Current Issues faced in Automation

• Integration and Long time Support

• System Upgrades

• Factory Support

• Enterprise Integration

Highlights of PLC

1.Low cost

2.Easy Design

3.Well Documented

4.Well supported by Industry

5.Faster Implementation

Why Does PLC Lag Behind..?

It doesn’t support the following characteristics:

• Peer to peer

• Single Database

• Security

• Alarms

• Advanced Math Functions

• Proprietary HMI

• Open Protocols

Inherent Features of DCS

1.Peer to Peer:

This benefit is seen by reduced wiring costs between controllers and with a reduction in engineering time based on simplified mapping.

2. Single Database:

The accuracy of the initial build and the maintenance of the system are made far easier with the single database. Transcription errors are minimized and changing tags in control schemes is much simpler.

3.Security:

Most PLC packages don't include Security Management in the package. It must be purchased and configured separately.

4. Alarms:

Most PLC packages don't include Alarm Management as part of the database which will add extra time and complexity to the project.

5. Advanced Math Functions:

PID calculations are done in the CPU of the PLC so multiple and complex calculations will slow down the process time. Additional costs may be required to do advanced math with add on cards.

6. Proprietary HMIs:

Many PLC vendors use their own HMI which makes interface to other devices difficult and training more expensive.

7. Open Protocols:

Some PLC vendors use proprietary protocols at the control level which makes communication difficult.

PLC Architecture

DCS

• A distributed control system (DCS) refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location (like the brain) but are distributed throughout the system with each component sub-system controlled by one or more controllers.

• The entire system of controllers is connected by networks for communication and monitoring.

• DCS is a very broad term used in a variety of industries, to monitor and control distributed equipment

Components of DCS

1. Introduction

2. Architecture

3. CPU

4. Analog Input Module

5. Digital Input Module

6. Analog Output Module

7. Digital Output Module

8. Communication System

9. Human Interface system (HIS)

DCS Architecture

The CPU• Model is chosen based on software to

be used.

• The main memory is ensured of high reliability by error correction code (ECC).

• Addition of the new error detection and protection functions.

• Other newly added functions include the memory management unit (MMU) and write protection which ensure data integrity, the parity check of addresses and data, the ECC memory, and a two wire signal self checker.

Analog I/O Module

• To input an analog voltage the continuous voltage value must be sampled and then converted to a numerical value by an A/D converter.

• The data value sampled will be somewhere between the voltage at the start and end of the sample.

• The maximum (Vmax) and minimum (Vmin) voltages are a function of the control hardware. These are often specified when purchasing hardware

Digital I/O Module

• The digital I/O module is configured by the card unit and either the terminal unit or connector unit.

• It inputs and outputs 16 or 32 signal points and converts signals.

• Since the types or I/O signals are software-set, no control switch or knob is found on this module.

Communication Systems

• The communication cards are used to realize the general-purpose communication of field control station and subsystems via serial links, so that the subsystem may be controlled or monitored.

Human Interface Station

The human interface system programmed for a project/plan is designed in such a way that it would be easy for the operator to understand all the operations occurred in the plant.

Nuclear Reactor Control Unit SCADA Based Interface

HIS and Monitoring Windows

Applications

1. Electrical power grids and electrical generation plants.

2. Environmental control systems.

3. Traffic signals.

4. Radio signals.

5. Water management systems.

6. Oil refining plants.

7. Metallurgical process plants.

8. Chemical plants.

9. Pharmaceutical manufacturing.

10.Sensor networks.

11.Dry cargo and bulk oil carrier ships

What’s Next..?