DCS ARCHITECTURE AND TDC 3000

Presented by:Ziauddin/M. Sohail/Haroon Yousaf

INTRODUCTION

DCS is the real time component of control system.Introduced in mid 1970s, it has became an essential component of Process plant control system.Control system reliability, flexibility and speed are basic functions, offered by DCS.

FUNCTIONSDISTRIBUTION

DCS distributes control tasks into relatively small sets of independent sub systems.Distributed tasks includes: Data collection. Process Control. Presentation of information Process analysis Storage / retrieval of information.

FUNCTIONSDISTRIBUTION

Advantages of Distribution: Lower exposure to component or

subsystem failure. Better isolation to facilitate

maintenance & upgrade. Flexibility for application

development.

FUNCTIONSCONTROL

This is to automate the process by integrating advanced regularity, logic & sequential control.Capable to handle multiple control loops and flexibility to change control strategies as per process demand.100 percent reliability on failure of any control component.

FUNCTIONSCONTROL

In addition to control, supports following: Information exchange with business,

logistics and transportation applications.

Preventive or Predictive maintenance scheduling.

Analysis for better control or trouble shooting.

FUNCTIONSSYSTEM

“System” organizes the command structure & information flow among its constituents part.This act as a single automation system unifying the various subsystem.The subsystem includes: Process signal input & conditioning. Process actuator signal output. Human readable process displays.

FUNCTIONSSYSTEM

Human actions i.e. set point changes, manual overrides and alarm handling.

Communications subsystems.

HIERARCHY OF DCS

Digital control along with networking allows process information to be passed from level to level within a corporation.This information flow represents the flow of measured variable from a flow transmitter to anywhere in the world.Such hierarchical representation of the information leads to a better understanding.Broadly, DCS hierarchy consists of 05 levels.

HIERARCHY OF DCSLevel “0” – Field Instruments

This level handles control and process information to & from the process field.Measurement devices provide the information on the current conditions of process.The actuators / control valves permit control decisions to be imposed on the process.Generally, analog / smart transmitters & control valves dominate this layer / level.

HIERARCHY OF DCSLevel “1” – Process Control

This level operates the process at or near the targets supplied by others.High degree of automation control is provided to achieve operation consistency.Reduction in variance in key process variables and uniform product quality are obvious benefits.

HIERARCHY OF DCSLevel “2” – Supervisory Control

Set points / Outputs and other controllable process variable can be changed to meet set targets.Plant optimization & emergency handling are the main features at this level.

HIERARCHY OF DCSLevel “3” – Engineering / Production Control

Configuration of new process values / alarms or change in control strategy is done at this level.New graphics displays configuration or amendments for better human interface.Tuning of Control loops.Long and short term Production planning of continuous and batch processes.

HIERARCHY OF DCSLevel “4” – Corporate information System

The upper most level of control system in a corporation.Long term and strategic functions are performed from this level.Inventory control on feedstock and subsequent contracts.Production forecast and requirement of raw materials.

TDC 3000 – An Introduction

TDC (Total Distribution Control) 3000 is the propriety product from Honey well, USA. TDC-3000 uses High level control language (CL) for system control and security strategies.Modular structure and its components communicates with each other, with redundancy.PM (Process Manager) – Control hub of the system, linked with communication channels from field and Central Control Room.

TDC 3000 – An Introduction

Information travels through high speed co-axial cable.Data monitoring and control via CRT consoles called Universal stations.Specially designed Keyboard to access max. no of input option for process control.Dedicated component for data storage and retrieval called History Module.

TDC 3000 – An Introduction

High level calculations / algorithms are carried out in AM (application module)Two communications cables, LCN & UCN for the integrity of the system.

TDC 3000 Architecture

NIM

U C N

PMU

C N

HMAMUS

MCField Signal

Note: All the communication is two way.

TDC 3000 Architecture

MARSHELLING CABINET Signal termination from field to DCS

cabinet and vice versa. Signal conversion and provision of

fuses to protect circuits.

TDC 3000 Architecture

PM Cabinet Contains I/O cards and Process Manager

modules. Redundant cards / modules are used for

system reliability. PM have all necessary algorithms / loop for

specific control strategy. UCN is the communication link / channel,

receives or transfer data to/from PM modules.

TDC 3000 Architecture

LCN Cabinet It houses NIM, an electronic card, link

for communication b/w LCN / UCN. Application and History modules also

reside in this cabinet. LCN is the communication channel for

high level modules i.e. NIM. AM. HM & IOUS.

TDC 3000 Architecture

DCS Consoles Universal Stations (US) are man

machine interface, also called IOUS. User friendly graphical displays to

control or view process parameters as a real time component.

Specially designed Keyboard to facilitate access of displays, alarms and controller. Touch screen feature for controlling.

TDC 3000 Components

I/O Modules The analog & digital points (signals)

processing carried out in I/OMs. Input Modules are:

Analog Input – high level Analog Input – low level Digital Input Pulse Input

TDC 3000 Components

Output Modules are: Analog out put Digital out put

Tasks executed in Input Modules, are Analog to digital conversion PV characterization Range checking Alarm detection PV source checking

TDC 3000 Components

Tasks performed by Output modules: Conversion of OP to 0 to 20 mA. Selection of direct / reverse controller

action.

TDC 3000 Components

Process Manager Highly flexible high-performance controller for

control. Configurable according to process requirements. Capable of executing 160 control loop at a time. Functions of I/O scanning through regulatory &

logic control to more advance control can be implemented.

The PM consists of Process Manager module & I/O subsystem

TDC 3000 Components

Process Manager Process Manager Module consists of:

Communication Processor & Modem I/O link interface Processor Control Processor

I/O subsystem consists of: I/O link (X-Bus) 40 redundant I/O modules

TDC 3000 Components

Process Manager The processing power of PM is measured in

terms of Processing Units (PU) & Memory Unit (MU)

One PM Module guaranteed the max. capacity of 560 PU and 7900 MU.

PU value determined by data type and scan rate.

MU value determined by type of data, max.for analog signals.

Max. 40 I/O modules can be hooked with PMM.

TDC 3000 Components

Universal Control Network Communication channel for PM to

high level modules. It is redundant coaxial cable and can

support up to 32 redundant devices. Supports peer to peer communication

with 5 megabit/sec network designed.

TDC 3000 Components

Network Interface module (NIM) It provides link between LCN and

UCN. Its changes protocol of UCN data for

LCN and vice versa. Forwards messages from network to

LCN. Available in redundancy.

TDC 3000 Components

Local Control Network (LCN) Data channel / cable for higher level

modules. Token passing protocol with rate of 5

megabits/sec. Co-axial cable handles 2000 bytes per

token. Supports max. 64 nodes.

TDC 3000 Components

History Module (HM) An LCN module, acts a network server

for loading software and data base into LCN modules.

Historizer for specified point parameters and system events.

Generates trends/reports as per configuration.

TDC 3000 Components

Application Module (AM) An LCN node, provides complex

calculations and advanced control. Allows control logic to access data

anywhere on the LCN. Control strategies in AM is

implemented by user friendly language called CL/AM.

TDC 3000 Components

Open Universal Station (IOUS) Human interface to process control, highest

level of LCN node. CRT display allows monitoring/control and

handling of alarms. Displays/prints trends, event history and

reports. Monitor system status and also used as to

build process and system database. Offers multi-window environment.