CONTROL SYSTEMS TYPES1) PLC

2) DCS

3) PC- Based Controls.

PLC • Sequentional logic solver

• PID Calculations.

• Advanced Subroutines

• BIT Operations.

• Data Transfer.

• Text Handling.

• Cost of hardware, software, Integration Engineering, Design, Installation, Start-up and Commissioning, Validation documentation and Execution, Training, Spare parts, Maintenance, System service contract and system life cycle.

• Reliability, Flexibility, Scalability and Validatability.

• Ease of Database configuration, Graphics development, Interlocks and Batch processing.

• Integration of High-level Application.

• Control Philosophy for Centralized versus Remote Operator Console or both.

• Compliance with an Industry batch standard such as ISA SP88 and new Communication Protocol.

PLC\DCS Selection Criteria

PROGRAMMABLE LOGIC CONTROLLERS

PLC • Sequentional logic solver

• PID Calculations.

• Advanced Subroutines

• BIT Operations.

• Data Transfer.

• Text Handling.

PLC Types• Nano (less than 1k RAM, 32 I/O)

• Micro

• Small

• Large (8 to 64k RAM, 512 I/O More)

Basic criteria for PLC Types• Memory Capacity

• I/O Range

• Packaging and Cost per Point

Applications :• Machine controls.

• Packaging.

• Palletizing.

• Material handling and similar Sequential task.

Advantages of PLC :• They are fast and designed for the rugged industrial environment.

• They are attractive on Cost-Per-Point Basis.

• These Devices are less Proprietary ( E.g.. Using Open Bus Interface.)

• These Systems are upgraded to add more Intelligence and Capabilities with dedicated PID and Ethernet Modules.

Disadvantages of PLC :• PLC were Designed for Relay Logic Ladder and have Difficulty with some Smart Devices.

• To maximize PLC performance and Flexibility, a number of Optional Modules must be added

• This Product Family also create Training and Installation problems.

PLC Types• Nano (less than 1k RAM, 32 I/O)

• Micro

• Small

• Large (8 to 64k RAM, 512 I/O More)

Basic criteria for PLC Types• Memory Capacity

• I/O Range

• Packaging and Cost per Point

PLC Systems Installation in RCF

1. Siemens --- Ammonia I

SIMATIC 115U

110U

2. Allen Bradley --- PGR,New Nitric Acid Plant

PLC 5/25 and 5/10

3. Allen Bradley --- KCL/DAP Bagging Plant,Ammonia I

SLC 5

4. GE Fanuc --- Ammonia Storage

90 - 30 Series

5. GE Fanuc --- New Bagging Plant

90 - 30 Series

6. Mitsubishi --- STP

PLC Cycle

Outputs

Machineor

Process

Programmablecontroller

Inputs

PLC Signal Flow

Programming Terminal

O:0/7

O:0/7

O:1/5

Output Devices

Output ModulesProcessor MemoryInput Module

Input DevicesLadder Program

O:0/7

O:1/5

I:0/6

I:1/4

O:1/5

I:0/6

I:1/4

I:0/6

I:1/4

Data InputImage Table

OutputImage Table

ALLEN BRADLEY PLC (DH+)

PLC-5 Controller

Workstation with RSLogix5 Software

Workstation

SLC-5/04 Controller

Features :

•Supports remote programming

•Common, existing standard

•Peer-to-Peer communications

Data Highway Plus

ALLEN BRADLEY PLC ARCHITECTURE (ETHERNET)

Modem

Internet

Laptop

PLC-5 Controller

Data Highway Plus

Ethernet Gateway.

PLC-5/20E Controller.

SLC-5/05 Controller.

PC Workstation

Ethernet

Comparison chart --- ALLEN BRADLEY PLC

MODEL TOTAL SYSTEM I/O

SCAN RATE/1K

PROGRAM MEMORY SIZE

DATA MEMORY SIZE

SLC500 72 8 ms 1K 4KSLC5/01 256 8ms 4K 16KSLC5/02 480 8ms 4K 16KPLC-5/10 512 2ms 6K 6KPLC-5/25 1920 2ms 21K 21KPLC-5/40 2048 0.5ms 48K 48KPLC-5/60 3072 0.5ms 64K 64KPLC-5/250 4096 <1ms 384K 384K

GE Fanuc - PLC

• GE Fanuc PLC Architecture : GE Fanuc ‘s series 90-30 PLC Family.

RemotePlatform

Host Platform

Wireless Modem

Wireless Modem

GE Fanuc 90/30 PLC

H M I Display

PC

GE Fanuc 90/30 PLC

90 - 70 PLC’s

Siemens PLC Communication

S5-115H S5-155H

S5-155US5-135U S5-100U

SINEC

Siemens PLC Architecture

Internal programMemory(RAM)

Memory submodule

Processor

ProcessImage

ForInputsAnd

Outputs

Timer

Counters

Flags

Inputs

ExternalCounters

Outputs

Program memory

I/O

I/O bus

Siemens Programming Methods

The program is generally written down before it is loaded into the programmable

controller. This can be done in the form of a

• Statement list ( STL )

• Control system flowchart ( CSF) or

• Ladder diagram ( LAD ).

The subsequent loading of the program into the S5-100U PC can take place in

two ways : Online ( Direct to internal RAM ) or Off-line ( EEPROM or EPROM ), i.e., with

the programmer connected or not connected to the programmable controller.

Siemens S5-100U Specification

CPU 100 U

Function range Boolean logic, bracketed operation, counter and timer functions, load, transfer, comparison and jump operation, arithmetic.

Programming language STEP 5

Methods of representation STL, CSF, LAD.

Execution time 70 msec.

Program memory ( Internal RAM )

1K

Flags 1024, ½ of which are retentive.

Digital Inputs

Digital Outputs

128 ( Max.)

Analog Inputs

Analog Outputs

8 ( Max.)

Comparison chart --- SIEMENS - PLC

MODEL TOTAL SYSTEM I/O

SCAN RATE/1K

PROGRAM MEMORY SIZE

DATA MEMORY SIZE

90U 8 2 msec 4 KB 4KB

95U 8 2 msec 16KB 16KB

100U 8 70 msec 2KB 2KB

102U 16 7 msec 4KB 4KB

103U 32 1.6 msec 20KB 20KB

135U 192 1.1 msec 46KB 64KB

155U 32578 0.2 msec 640 KB or

1.6 MB

640KB or 1.6MB

PLC Architecture Evolution• Mid - 1970s : Discrete Machine Control

ProgrammingTerminal

PLC

I/O

Connection is Point to Point

Programming Language :

- Relay ladder logic - Flexibility in altering control system operation

• Early - to - Mid 1980 : Discrete and Process Control

PLC Architecture Evolution

Reasonable ComputerRunning PLC

Programming Software

PLC

I/O

Programming Language :

- Ladder Program - PID - Data Storage

MS - DOS

PLC Architecture Evolution

• Late 1980’s to early 1990’s : Discrete and Process Control

PC running PLC Programming Software

PLC

I/O

Connection in networked allowing Multiple PLC

PLC became a part of the developing enterprise resource system

Windows

PLC Architecture Evolution

• Today : Enterprise Control

NT - Based PC running Control Development Software

CE Based Open Control Unit

I/O

Program Download Connection

Open Solutions

Ethernet - enterprise network connection

Ethernet

Ethernet was originally designed by Digital, Intel and Xerox (DIX) in the early 1970’s

and has been designed as a broadcast system. The original format for Ethernet was developed

in Xerox Palo Alto Research center (PARC), California in 1972. The two inventors were

Robert Metcalf and David Boggs.

Ethernet version 1.0 and 2.0 followed until the IEEE 802.3 committee re-jigged the

Ethernet II packet to form the Ethernet 802.3 packet. Nowadays you will see either

Ethernet II (DIX) format or Ethernet 802.3 format being used.

The ‘Ether’ part of Ethernet denotes that the system is not meant to be restricted only to

one medium type, copper cables, fiber cables and even radio waves can be used.

Briefly, stated Ethernet what is referred to as the Physical layer and the Data-link layers

protocols. The physical layer defines the cable types, connectors and electrical characteristics.

The Data link layer defines the format an Ethernet frames, the error checking method and the

physical addressing method. As Ethernet is only a Physical/Data link layer other protocols

need to be added on top of it to address the issues of routing, end-to-end data integrity and

house specific network task are carried out.

10Base5

Traditionally, Ethernet is used over ‘thick’ coaxial cable called 10Base5 ( the 10

denotes 10 Mbps, base means that the signal is baseband i.e, takes the whole bandwidth

of the cable, 5 denotes 500m maximum length ). The minimum length between stations

is 2.5m.

The cable is run in one long length forming a ‘Bus Topology’. The segments are

terminated by 50 ohm resistor and the shield should be grounded at one end only.

10Base2

Thin Ethernet (Thinnet) uses RG-58 cable and is called 10Base2 (the 2 denotes

200 mtr maximum length cable). Each station connects to the Thinnet by way of

Network Interface Card (NIC). At each station the Thinnet terminates at a T-piece and

at each end of the Thinnet run a 50 ohm terminator is required to absorb stray signals

thereby preventing signal bounce.

Ethernet

10BaseT

Nowadays, it is becoming increasingly important to use Ethernet across Unshielded

Twisted Pair (UTP) or Shielded Twisted Pair (STP), this being called 10BaseT (the T

denotes twisted pair). UTP is installed in star wire format and Ethernet Hubs with UTP ports

(RJ45) centrally located. Also there should be no more than a 11.5db signal loss and the

minimum distance between devices is 2.5 meters.

The advantages of the UTP/STP technology are gained from the flexibility of the

system, with respect to moves, changes, fault finding, reliability and security.

10BaseF

10BaseF standard developed by IEEE 802.3 committee defines the use of Fiber for

Ethernet. 10BaseFB allows upto 2 Km per segment and is defined for Backbone application

such as cascading repeaters. 10BaseFL describes the standards for the Fiber optic links

between stations and repeaters allowing upto 2 Km per segment on multimode Fiber.

Ethernet

The following table shows the RJ45 pin outs for 10BaseT :

RJ45 Pin Function Colour 1 Transmit White/Orange

2 Transmit Orange/White

3 Receive White/Green

4 Blue/White

5 White/Blue

6 Receive Green/White

7 White/Brown

8 Brown/White

Ethernet

Controller ControllerController

Controller

Workstation Workstation Workstation Workstation

Switched Hub

Segmented (star) topology Bus topology Ethernet Topology

PLC conceptual overview

Process Graphics

History &Trend

Alarm &Events

SCADA configuration

editor

Other Aspectsystem

ABB Siemens AllenBradley

GEFanuc ….

opc Modbus comliProtocol

xxProtocol

yy

SCADAserver

OPC server

OP Client SCADA ControlAspect

Real-time database

Process control Software characteristics The most important feature of process control system is that it needs to be reliable. The

process control system used has to be completely crash-proof and any changes in the

system need to be made on-line.

The process control needs to be made real time, which means that it can update the I/O

data table and process the control program in the time required by the process.

A process control system that is deterministic refers to whether the operating system

allows the highest priority task to work without interruption from task with lower priority.

Software offerings in the automation and the process control fields must be versatile and

open enough to address the needs of different applications.

Finally the chosen solution must deliver tangible, quantifiable values such as :

1. Reducing project implementation time and cost.

2. Improving time-to-market.

3. Achieving higher production and quality.

4. Cutting maintenance and training cost.

5. Increasing profits.

PC-based control system features

Unlike the other systems, PCs provide a more open architecture making them ideal for

improving, optimizing and integrating the overall automation process, as well as conducting

control task.

In addition PCs offer the following features :

• Lower cost.

• Ease of use.

• Graphical user interface.

• Easy integration of logic, motion and process control.

• Simplified application development.

• Software portability

• Independence from proprietary control system.

Using PCs enable the following functions,

• Millisecond time stamping which is essential to utilities.

• Real time control.

• Sequence of events.

• Alarming.

• Data collection.

Windows NT features

Windows NT is gaining ground in open control because of the following advantages :

• User acceptance.

• Corporate interoperability

• Ease of use.

• Connectivity.

• Scalability for small and large application.

However, Windows NT has the following disadvantages :

• Needs a lot memory and processing power.

• Optimized for office, not control, requirements.

• Requires a disk drive which may fail.

• Depends on single vendor.

• Reboots at unexpected times

• Unstable operating system.

QNX Features

QNX real-time operating system, has evolved from the first-ever micro-kernel operating

system for PCs into one of the best selling and most trusted operating systems for mission

critical application. Today, QNX is the real time operating system in industrial automation,

hand held devices, controllers and soft PLCs

QNX is recognized as :

• The fastest and most dependable real time operating system.

• The most proven high speed, deterministic real time kernel.

• Having a hard real time engine that gives PLC-style control.

• Enabling data acquisition with milliseconds resolution.

• Providing a fault-tolerant architecture on which you can run control, events, alarms in a virtually crash-proof environment.

PLC Programming Standards

The open, manufacturer-independent programming standard for automation is

IEC 61131-3. You can thus choose what configuration interface you wish to use when

writing your application :

• Ladder Diagram

• Instruction List

• Function Block Diagram

• Sequential Function Chart

• Structured Text

All users, be they plant electrician or computer scientists, thus have a configuration interface in which they can feel at home.

Industrial IT Trends

The availability of information is becoming increasingly crucial in the view of growing global

competition. In future, a decisive competitive edge can only be achieved by providing the

right information at the right time, in the right place and in the right form for the right person.

these leading- edge application are continuously optimized and repositioned.

Industrial IT consists of five components:

1. Engineering IT

2. Operation IT

3. Production IT

4. Optimization IT

5. Evolution / Information

ASSET OPTIMIZATION

Industrial IT Trend

Sales & Marketing

Planning & Scheduling

Plant & Process Eng.

Operation & Maintenance Distribution

Real-timeAutomation &Information

e-PRO

DU

CT

IVIT

Y

Business Systems

Plant