wireless communication system for supervisory pressure control

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PROJECT REPORT

WIRELESS COMMUNICATION SYSTEM

for

Supervisory pressure control

By

Ashfaque AlamDMU Std ID: p10369638

____________________________________________________________Submitted in fulfillment of the

FINAL YEAR INDIVIDUAL PROJECT (ENGD3000)

to be awarded BEng (Hons) in Electronics Engineering;

Under the supervision of

Dr. Piotr Skworcow



Ashfaque Alam|p10369638

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ACKNOWLEDGEMENT

I have been immensely motivated, inspired, helped and supported by my nearest and

dearest friends, families and folks. It is simply not possible to thank them enough andin trying to mention all their names and their contribution would mean composing

another dissertation.

Dr. Scarecrow, with his continuing and consistent guidance and support, has always

been by my side through times of hardship and success, showing me the right path and

always offering me his priceless advices. Without his all-out support, this research

work would not have been possible.

De Montfort University, being the heart of Leicester, had its own charm. Starting from

Queens building, where hours and hours of work has been done, to the printing and

binding shop, each step was made simpler due to easy access of equipment and

information available at all times. The staffs, even during their worst days of the year,

were always friendly and offered to lend a helping hand.

Special recognition should go to my Father, Mother and Brother also my friends-

Shakhi, Shishir, Kalpesh, Riyaz, Sadiyah, Areez, and Trigwell. Without their consistent

encouragement, inspiration, drive and support through rain and storm, this research

would have never been as fruitful. To them I extend my most cordial gratitude.




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ABSTRACT

Temperature, pressure, flow, level etc are the common process variables for any real

system. Similar to the others, pressure is another key process variable for providingcritical condition of boiling, mining, chemical reaction, distillation, extrusion,

vacuuming, air conditioning etc. As a result the concept of pressure control system has

turned into a widely used industrial application where a pre-sated outlet pressure is

meant to be maintained throughout an implemented arrangement. The fundamental

theory is kept as it is to the general feedback control system, that focuses on

the modelling of a diverse range of dynamic system (e.g. mechanical systems) and the

design of controller that will cause the system to behave in the desired manner.

Supervision, by definition acquires slightly different methodology than that of

controlling. Supervisory control refers to the arrangement of not only controlling any

system but also coordinating all the subsystems in real time.

The paper investigates the plan to wirelessly supervise the pressure control system using

necessary equipments, controllers and set of instructions. As for any supervisory control

system there is the necessity of maintaining a continuous Human-to-Machine Interface

(HMI), a Remote Terminal Unit (RTU) or Programmable Logic Circuit (PLC) or any other

integrated device connected to the sensor that converts the sensed signal into desired

one and passes the data to the media that carries it to supervisory system and

necessary communication infrastructure; the report has focused on all the necessary

terms and parameters to be described.

Because of being a very early attention-grabbing technique there have been a several

previous works of remote supervisory control taken. The paper also draws comparison

with prior and continuing works done on Wireless supervisory control system. Most

importantly, the fundamentals of the techniques taken here have been figuratively

illustrated along with exemplary practices in order to prove the taken technique fruitful

and to give the future researchers a complete guideline of taking this project further to

the optimal level. Wireless supervisory pressure control system has also been shown to

play a role in attaining better performance in practical appliance.




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GLOSSARY

A/D (ADC) Analogue to Digital Conversion

ANSI American National Standards Institute

AT Attention Terminal

Bit Binary Digit

D/A Digital to Analogue Conversion

ESD Emergency Shut Down

GPRS General Packet Radio System

GUI Graphical User Interface

HIPPS High Integrity Pressure Protection System

HMI Human-to-Machine Interface

IDE Integrated Development Environment

IED Intelligent Electronic Device

Kbps Kilo Bit per Second

LED Light Emitting Diode

MTU Master Terminal Unit

OS Operating System

PAC Process Automation Controller

PC Personal Controller

PCI Peripheral Component Interconnect

PDA Personal Digital Assistant

PIC Peripheral Interface Controller

PLC Programmable Logic Circuit/Controller

POT Potentiometer

PRV Pressure Reducing Valve




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PSD Production Shut Down

RF Radio Frequency

RS-232 Recommended Standard-232

RTU Remote Terminal Unit

SCADA Supervisory Control and Data Acquisition

SIM Subscriber’s Identity Module

SMS Short Message Service

UART Universal Asynchronous Receiver/Transmitter

USB Universal Serial Bus




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____________________LIST OF CONTENTS

CHAPTER PAGE

NO.

1 INTRODUCTION 09

1.1 PRESSURE CONTROL SYSTEM 09

1.2 SUPERVISORY CONTROL 10

1.2.1 Autonomous supervisory system 10

1.2.2 Human supervisory system 10

1.3 WIRELESS COMMUNICATION FOR SUPERVISIORY SYSTEM 11

2 BACKGROUND 122.1 HISTORY & EVOLUTION OF SUPERVISORY CONTROL 12

2.2 RELATED WORKS 14

2.2.1 Emergency shutdown (ESD) system 14

2.2.2 High integrity pressure protection system 14

2.2.3 Supervisory control and data acquisition (SCADA) system 14

2.3 PRACTICAL ASPECT 15

3 PROJECT ARCHITECTURE 16

3.1 CONVENTIONAL ARCHITECTURE 16

3.2 ELECTRONIC FRAGMENTS TO WORK ON 17

3.3 SPECIFIC ARCHITECTURE OF THE PROJECT 18

4 PROJECT COMPONENTS 22

4.1 HARDWARE USED FOR THE PROJECT 22

4.1.1 Pressure Reducing Valve (PRV) 22

4.1.2 Modulo Controller 23

4.1.3 Explorer 16 Development Board (PIC24 Micro-Controller) 23

4.1.4 Wavecom M1306b (GPRS Module) 24

4.1.5 Connection Leads (RS232 & Converters) 25

4.1.6 PCI Cards (With RF Connectors) 25

4.2 SOFTWARE USED FOR THE PROJECT 26

4.2.1 MPLAB Integrated Development Environment (IDE) 26

4.2.2 MPLAB C30 (C Compiler) 26

4.3 HUMAN MACHINE INTERFACE 27




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5 IMPLEMENTATION 28

5.1 PROGRAMMING MICROCONTROLLER 28

5.1.1 Receiving Analogue Signals 28

5.1.2 Communicating With GPRS Module 34

5.2 ENABLING HMI 38

5.2.1 Terminal Set-Up 38

5.2.2 Wireless Communication 38

5.3 DIFFICULTIES FACED & CAUTIONS REQUIRED 40

6 ANALYSIS AND DISCUSSION 42

7 SCOPE FOR FUTURE RESEARCH 43

8 CONCLUSION 44

REFERENCE 45

BIBLIOGRAPHY 49




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_______________________LIST OF FIGURES

SERIAL FIGURE TITLE PAGE

2-1 Evolution of Supervisory System

3-1 Complete Project Overview 3-2 Specified Project Overview

3-3 Specifically Detailed Architecture

4-1 PRV Cross-Section

4-2 Explorer 16 PIC24 100 Pin Development Board

4-3 GPRS Module

4-4 RS232 Cable

4-5 RS232-USB Converter

4-6 PCI Card with RF Connector

5-1 Programmer Setting

5-2 Programming A/D Conversion Code

5-3 LED Position Changing with Potentiometer Variation5-4 Selecting the COM Port

5-5 Configuring Teraterm

5-6 Transmitting Character through RS-232

5-7 Sending Text to mobile using AT command

5-8 Sent Text using GPRS Modem

5-9 Receiving Text from mobile using AT command




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CHAPTER 1

INTRODUCTION

As per definition, the major aim of any control system is to design systems withpredictable behavior thus the aim of control engineering

1. In this fast growing age of

industrial complexities, verity of controlled criterions are mounting as the time is

passing. These decisive factors of any under-designing process those often known as

process variables are mainly natural signals or Analogue indications, as for any real-life

control system requires some pre-specified natural/Analogue outcomes at the end2.

This thesis aims to play with one of the process variables- pressure. In this paper, the

titled phrase “Wireless Communication for Supervisory Pressure Control 3” comes with a

requirement of some terms to be described. With the aid of necessary verbal and

figurative descriptions those terms have been discussed in relation with the action

plan.

1.1 PRESSURE CONTROL SYSTEM

The pressure control system normally comprises the pressure regulating system and

the pressure safety system as well as notification systems and instrumentations to

monitor the operation. The pressure regulating system ensures that the pressure in

the pipeline is kept at a certain level. The pressure safety system denotes the

equipments that ensures the accidental pressure to be kept bellow set value.4, 2

In this Chapter

Pressure Control System.

Supervisory Control and its classifications.

Wireless Communication for supervisory system.




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Poor pressure control can cause major safety, quality, and productivity problems.

Overly high pressure inside a sealed vessel can cause an explosion. Therefore, it is

highly desirable to keep pressure in good control and maintained within its safety

limits.

2

1.2 SUPERVISORY CONTROL

Supervisory control is the general term for coordinated control of many

individual controllers or control loops, whether by a human or an automatic control

system, although almost every real system is a combination of both. Supervisory

control often acquires two forms taking the acting process into account.5

They can be

defined as Autonomous/Strictest system and Human Supervisory control system/less

strict system.5, 6

1.2.1 Autonomous Supervisory System

The controlled machine or process continues autonomously. It is observed from time

to time by a human who, when deeming it necessary, intervenes to modify the control

algorithm in some way.5

As per Sheridan6

defines, “In the strictest sense, supervisory

control means that one or more human operators are intermittently programming and

continually receiving information from a computer that itself closes an autonomous

cont rol loop through artificial effectors to the controlled process or task environment.”

1.2.2 Human Supervisory System

The process accepts an instruction, carries it out autonomously, reports the results and

awaits further commands.5

As per Sheridan6

defined, “In a less strict sense, supervisory

control means that one or more human operators are continually programming and

continually receiving information from a computer that interconnects through artificial

effectors and sensors to the controlled process or task environment.”




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1.3 WIRELESS COMMUNICATION FOR SUPERVISORY SYSTEM

As Per the project requires, this report has been prepared investigating the wireless

communication between supervisory system and control system. By definition,

wireless communication is the transfer of information without the use of wires.7, 8

The

distances involved may be short (a few meters as in television remote control) or long

(thousands or millions of kilometers for radio communications). The term is often

shortened to "wireless". It encompasses various types of fixed, mobile, and portable

two-way radios, cellular telephones, Personal Digital Assistants (PDAs), and wireless

networking. Other examples of wireless technology include GPRS modules, garage

door openers and/or garage doors, wireless computer mice, keyboards and headsets,

satellite television and cordless telephones.7, 9

__________________________________1Control engineering, Available at: http://en.wikipedia.org/wiki/Control_engineering [Accessed on:

05.23 am 13 May 2011]2Pressure control , (2011), CyberSoft, General Cybernation groups inc. Available at:

http://www.cybosoft.com/solutions/pressurecontrol.html [Accessed on: 05.30 am 13 May 2011]3Project Instruction provided the supervisor.

4Bræstrup. M. W, Andersen J. B, (2005), Pressure control systems, Design and installation of marine

pipelines, Blackwell Science Ltd, Blackwell Publishing Company, OXFORD, UK, pp- 415Supervisory Control , Available at: http://en.wikipedia.org/wiki/Supervisory_control, [Accessed on:

02.45 am 13 May 2011]6Sheridan, T. B, (1992), Human supervisory control, supervisory control, Tele-robotics, automation, and

human supervisory control, Massachusetts Institute of Technology Press, USA, pp-017Robels, R. J, Kim, T. H, Advances in Computational Intelligence, Man-Machine Systems and Cybernetics,

Architecture of Wireless Supervisory Control and Data Acquisition System, Multimedia EngineeringDepartment, Hannam University, Korea, pp- 2438"Wireless Communication" . Available at: http://www.sintef.no/content/page1____11881.aspx.

[Accessed on: March 2011]9Wikipedia "Wireless" , Available at: http://en.wikipedia.org/wiki/Wireless [Accessed on: 01.09 pm 10

May 2011]

http://en.wikipedia.org/wiki/Control_engineering


http://www.cybosoft.com/solutions/pressurecontrol.html


http://en.wikipedia.org/wiki/Supervisory_control


http://www.sintef.no/content/page1____11881.aspx


http://en.wikipedia.org/wiki/Wireless











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CHAPTER 2

BACKGROUND

For any new technique to be evolved it requires some practical influences and any

technical evolution occurs due to some situational changes. From the very beginning of

the control engineering, this branch of knowledge has been evolved from mainly

mechanical to electrical system10

; and because of discovering the necessity of process

variation, the age old system did not remain constrain to only velocity control10

, rather

than being spread out to be applied for position, temperature, flow or pressure etc.

Thus for the supervisory communication bit the technology got transformed from

wired to wireless system. So, this section is going to focus on the brief history of

pressure control system to be evolved into wirelessly connected supervisory control

system and on the reality reasoning of this evolution, as a result the real life necessity

of this investigative paper be more clearly exposed.

2.1 HISTORY & EVOLUTION OF SUPERVISORY CONTROL

After being invented as the first ever reality feedback control mechanism in 1788 by

James Watt the Watt’s Governor11

took quite a long time to let the control system

develop further, till in 1868 Maxwell’s Famous paper “On Governor” comes out along

with the Feedback control theory11, 12

. Even well after Maxwell’s effort the same

mechanism with its erroneous behavior grabbed attention of the scientists. Mainly the

then emerging and risky mining environments pioneered the necessity of a new

concept of pressure control, when the uncontrolled release of oil/gas from a well while

drilling started becoming common, known as oil gusher, gusher or wild well during the

late 19th and early 20th centuries13

. This gushers later on got investigated and named

In this Chapter

Evolution & History of Supervisory Control.

Related Works.

Practical Aspects




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as Blowout and define- the uncontrolled release of crude oil and/or natural gas from

an oil well or gas well after pressure control systems have failed13, 14,

.

So, the idea of pressure control system started to come into scene and gradually been

spread out into other sectors like water control, aircraft modeling and even in

aerospace engineering etc. This booming industrial utility then came up with the

requirement of directly supervising larger area system, thus started feeling the

necessity of automatically synthesizing supervisors that restrict the behaviour of a

plant such that as much as possible of the given specifications are fulfilled15

. The first

Supervisory Control Theory then was introduced in the name of Amadge-Wonham

framework15, 16

.

Now chapter 1.2 of the report elaborates both the successively invented supervisory

systems those finally been evolved in accordance of inter-system communicational

network type. During late 60s and mid 80s scientist like Thomas Sheridan, WR Ferrell,

Hennessy put a significant effort on merging the radio communication technology with

supervisory control system in order to outline an intelligent supervisory system17

.

Figure 2-1 bellow illustrates the brief evolution of supervisory system as Thomas

Sheridan observed:

Figure 2-1. Evolution of supervisory system17




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2.2 RELATED WORKS

There has been systematic research over the past few decades on intelligent

Supervisory techniques for pressure control over wireless and wired networks. Some

of the relevant works, as required for this report, have been outlined in the following

sections.

2.2.1 Emergency Shut Down (ESD) system

For longer, large diameter gas or petroleum pipeline systems intended to be used for

overpressure protection is a must to be designed. The level of protection required and

the associated requirements to the protection system should also be evaluated.

Installation of safety pressure relief devices (pressure safety relief valves) along withinstallation of a remotely or directly operating pressure limiting system which shuts off

the gas supply to the pipeline is used and well known as Emergency Shut Down (ESD)

system. For gas pipelines ESD, or PSD for production flow-lines, is now a days almost

mandatory as the supervisory pressure control system18

.

2.2.2 High Integrity Pressure Protection System (HIPPS)

Pipelines where the well fluid pressure drives the flow and pipelines intended for liquid

service may also be designed with a High Integrity Pressure Protection System (HIPPS),

as a part of the overall field pressure control philosophy. Pipelines for liquids where

rupture has a limited and not potentially fatal effect, for example, water injection lines

and chemical/service lines, will naturally have less need for a pipeline safety system.

This system mainly can be portrayed as cost effective version of ESD18

.

2.2.3 Supervisory Control And Data Acquisition (SCADA) system

The term SCADA usually refers to centralized systems which monitor and control entire

sites, or complexes of systems spread out over large areas (anything from an industrial

plant to a nation). Most control actions are performed automatically by programmable

devices. SCADA system monitors the overall performance of the loop using supervisory

mediums like Wired connection, radio connection, wireless connection etc. This is the

technology which can be pretty similar to the desired one here in this report18, 19

.




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2.3 PRACTICAL ASPECT

According to the so far discussion the practical necessity of a pressure control system

which is wirelessly supervised should quite easily be predicted- safety. Moreover, a

wirelessly communicated supervision may also refer to a cost effective technique in the

physical end, a time saving and effortless technique in terms of not having physical labour

on the field and a more comfortable, intelligent & accurate (thus effective in a word)

supervision technique. Moreover, in case of reducing background leakage and incident of

pipe bursts in water utility system20

, which often known as wastewater21

management and

in the petroleum mining environment as been said before the need of a more accurate,

intelligent and safe pressure control system is very important. As in very brief this will-

Remotely maintain the pressure control system. Reduce cost & risk of direct labor involvement and construstion.

Conserves time of the wired labor involvement that is needed for normal control

system because of not being able to follow remote instructions.

_________________________________

10 Maxwell, James Clerk, (1868). On Governors, Proceedings of the Royal Society of London. pp. 270 –

283.

11Hills, (1996), Power From the Wind , Cambridge University Press

12Watt’s Governor, Available in: http://en.wikipedia.org/wiki/Centrifugal_governor#cite_note-0

[Accessed at: 13.53 in 16th

May, 2011]

13R. Westergaard, (1987), All About Blowout , Norwegian Oil Review, pp- 13-17

14R. Westergaard, (1987), All About Blowout , Norwegian Oil Review, pp- 81-82

15Ramadge R. J, Wonham W. M, (1987), Supervisory control of a class of discrete event processes , SIAM

J. Control and Optimization, 25(1), pp. 206-230

16Supervisory Pressure Control, Available in:

http://en.wikipedia.org/wiki/Supervisory_control_theory

[Accessed at: 15.46 in 16th

May, 2011]

17Sheridan, T. B, (1992), Human supervisory control, supervisory control, Tele-robotics, automation, and

human supervisory control, Massachusetts Institute of Technology Press, USA, pp-02-03

18Mikael W. Bræstrup, Jan Bohl Andersen, (2005), Design and installation of marine pipelines, Blackwall

science limited, Oxford, UK, pp- 41-44

19Common system components, SCADA, Available in: http://en.wikipedia.org/wiki/SCADA [Accessed at:

18.00 in 17th

May, 2011]

20AbdelMeguid H., Skworcow P. and Ulanicki B., "Mathematical modelling of a hydraulic controller for

PRV flow modulation", Journal of Hydroinformatics, January 2011 (in press), pp- 05

21Wastewater system, Available in: http://en.wikipedia.org/wiki/Wastewater

http://en.wikipedia.org/wiki/Centrifugal_governor#cite_note-0




http://en.wikipedia.org/wiki/SCADA



http://en.wikipedia.org/wiki/Wastewater










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CHAPTER 3

PROJECT ARCHITECTURE

Wireless Supervisory Control systems are composed of computers, controllers,

instruments, actuators, networks, and interfaces that manage the control of

automated industrial processes and allow analysis of those systems through data

collection. In the following section, the conventional installation of the system and the

architecture for wireless communication is discussed.

3.1 CONVENTIONAL ARCHITECTURE

For the control of inlet air/fluid pressure a pressure reducing valve (PRV) is often usedto reduce the amount of pressure in a system of pipelines or in a tank. The valve has an

opening through which pressure can be released. Since the amount of pressure inside

a tank or pipe system can change, the valves can often be adjusted to release more or

less pressure22, 23

. The pressure control valve should work using the pressure in a tank

or be opened manually using direct reference setting or by setting required reference

point through flow modulated Modulo Controller using wireless medium. But for a

wireless supervisory control environment the reference control point or control signal

is designed to be generated by the human supervisor by assessing the provided

external signals- Inlet pressure, Outlet pressure, Flow measurement derived from the

three sensors installed to the system pipeline22, 24

. The mechanism so far described

indicates this project to be more a supervisory control than a fully automatic control as

introduced by Sheridan and described in the chapter 2.117

. But more likely the whole

system seems to be more mechanical than electronic.

In this Chapter

Conventional architecture of the project.

Electronic scopes to be implemented.

Specific structure of the project.




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3.2 ELECTRONIC FRAGMENTS TO WORK ON

Here comes the method of receiving Analogue data from the installed sensors and

digitally transmitting them to the Remote Terminal Unit (RTU), the device which is

responsible for processing the data and making them suitable to wirelessly transmit.

This local processor communicates with the site’s instruments and operating

equipments. Conventionally, this includes the Programmable Logic Controller (PLC),

Intelligent Electronic Device (IED) and Process Automation Controller (PAC) etc. A

single local processor may be responsible for dozens of inputs from instruments and

outputs to operating equipments25

. Here a point to be noted is a PLC may not be

always the best solution to use in particular cases, because of being constrain to one

specific environment and readily made for that environment with a non-versatile,

expensive and large sized characteristic. On the other hand a Peripheral Interface

Controller (PIC) is a device that can be effortlessly programmed and reprogrammed as

required in a low cost and small size. In a word a PIC micro-controller which is very

small, very cheap and very versatile, can be often a better choice to control the RTU

than that of PLCs26

. Here a PIC24FJ128GA010 micro-controller has been used

throughout the implementation portion.

Short range communications are needed between the local processors and the

instruments and operating equipment. These relatively short cables or in this case PCI

card27

carry Analogue and discrete signals using electrical characteristics such as

voltage and current, or using other established industrial communications protocols

say for the one suitable in this case- an RF connector25, 27

.

For wireless supervision the Master terminal unit (MTU) which could be called the

brain of the system that act as the central point of monitoring and control where ahuman operator can supervise the process; receive alarms, review data and exercise

control can be connected with the RTU via satellite, microwave, frame relay or cellular

packet data. . Moreover one or more remote terminal units (RTU). The RTUs gather the

data locally and send them to the MTU which then issues suitable commands to be

executed on site25

. A system of either standard or customized software is used to

collate, interpret and manage the data which is used as the Human Machine Interface




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(HMI) that can be even designed simply using the OS (Operating System) integrated

terminal emulators25, 28

.

So, according to the overall project requirements along with the electronic scopes to

be fulfilled by the project, the near-conventional structure can be illustrated as follows

in figure 3-122,29

.

Figure 3-1. Complete project overview 29

3.3 SPECIFIC ARCHITECTURE OF THE PROJECT

The to the point aim of this project is to programmeme and implement a custom

developed board that imitates the flow measurement signal to change the set-point of

Pressure Reducing Valve (PRV) according to the set-point (reference voltage derived

from required pressure) received from control room PC. To receive instruction and

control the mechanical part of the system according to that Modulo controller’s flow -

modulation mode is used.

As per the project background describes above, the part that actually has to be

focused on in order to get this project done is mostly in touch of the microchip board

only. The next block diagram in figure 3-2 shown below is more specific towards the

project, which shows those parts to be designed during the project that emphasize on

programming a micro-controller board in order to read, transmit and receive necessary

Analogue-digital signals resulting from a remotely situated PC.




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Figure 3-2. Specified Project Overview 22

The above figure 3-2 sets functionality for both of the Microchip part as well as for the

control room pc. They can be printed as follows:

Functionalities of the communication device (electronic board):

Communicating with GPRS module.

Reading the Analogue signals (inlet pressure, outlet pressure, flow) in a regular

time interval and transmit them via GPRS to the ‘control room’ PC.

Receiving set-point via GPRS from the ‘control room’ PC and generate pulse-

frequency-modulated signal according to the set-point.

Functionalities of a ‘control room’ PC:

Communicating with GPRS (General Packet Radio System) module

Receiving values of 3 signals (inlet pressure, outlet pressure, flow) via GPRS,

display them on the screen and save to file.

Transmitting set-point defined by operator via GPRS to the communication

device.

Bellow, a very elaborated and specific diagram has been presented to illustrate the

overall project architecture along with the workable bits and pieces indicated in figure

3-3 :




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Figure 3-3. Specifically Detailed Architecture




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Here the GPRS module is used as the ready solution for remote wireless applications,

connection between electronic board and control room PC and remote data

communications in the project environment30

.

---------------------------------------------------------22

Alam A, (2010), Project Background and Literature Review, Interim report for Wireless Communication

system for supervisory pressure control , pp – 04

23How a Pressure Control Valve Works, eHow.com, Available at: http://www.ehow.com/how-

does_4898894_how-pressure-control-valve-works.html#ixzz18LUcUsCF [Accessed at 05.53, on 17

December 2010 ]24

Bailey D. and E. Wright, (2003), Practical SCADA for Industry.25

Robels, R. J, Kim, T. H, Advances in Computational Intelligence, Man-Machine Systems and Cybernetics,

Architecture of Wireless Supervisory Control and Data Acquisition System, Multimedia Engineering

Department, Hannam University, Korea, pp- 242-24326

Robles R. J et al, International Journal of Future Generation Communication and Networking ,

Vulnerabilities in SCADA and Critical Infrastructure Systems, Multimedia Engineering Department, Hannam

University, pp- 99-10427

Difference between PLC and PIC, Available at: http://www.electro-tech-online.com/microcontrollers/10969-difference-between-plc-pic.html [Accessed at 05.53, on 17 May 2011

]28

Operating instruction, Human Machine interface, Intelligent Motion Systems, Inc, pp- 18-20, Available at:

http://www.faberinc.com/ReferenceMaterials/IMS/IMS_HMI_Manual.pdf 29

Taken from the Project instruction provided by the supervisor.30

Communication module with GSM or Analogue modem, STS, available at:

http://www.stssensors.com/contento/LinkClick.aspx?link=media%2FEnglisch%2FPDF%2FGSM_120_DED0

44A.pdf&tabid=74&mid=792&language=de-CH [Accessed at 08.10, on 17 May 2011 ]

http://www.faberinc.com/ReferenceMaterials/IMS/IMS_HMI_Manual.pdf


http://www.stssensors.com/contento/LinkClick.aspx?link=media%2FEnglisch%2FPDF%2FGSM_120_DED044A.pdf&tabid=74&mid=792&language=de-CH









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CHAPTER 4

PROJECT COMPONENTS

Supervisory control systems typically have 3 major components- The Hardware

Components, Software Components, and the Human Machine Interface25, 31. All the

components are being briefly described in this chapter with necessary specifications and

figurative representations:

4.1 HARDWARE USED FOR THE PROJECT

The externally used hardware for the project are mainly the Pressure Reducing Valve

(PRV) and the flow modulated modulo controller. And the internally used hardware

those have been directly used in preparing the project are mainly the micro-chip board,

the GPRS module and the control room pc itself. All the hardware components are

illustrated in this chapter.

4.1.1 Pressure Reducing Valve (PRV)

A Pressure Reducing Valve or pressure regulator is a valve that automatically reduces the

flow of liquid/gas at a certain pressure following a set of instruction given into it. In this

project PRV is used to allow high-pressure fluid

supply lines or tanks to be reduced to safe and/or

usable pressures for the application of water

utilities which is ran by the instructions coming

through a modulo controller32

. Figure 4-1

illustrates a conventional PRV with its general

mechanisms indicated.

Figure 4-1. PRV Cross-section

33

In this Chapter

Hardware used for the project.

Software used.

Human Machine Interface used.




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4.1.2 Modulo Controller

Modulo is a Flow Modulated PRV Controller that can be used to provide either Flow

Modulated or Time based pressure control in water networks or at major sites. The flow

modulated PRV controller is ran by the signals provided through the RTU programmedwith the flow profiles and pressure relationship between the valve and the "critical

point"34

. The pressure is increased or decreased depending on the flow data from

the the flow meter and the pressure data from the internal pressure sensor (Figure 3-3).

4.1.3 Explorer 16 development board (PIC24 Micro-controller)

The Explorer 16 is a low cost, efficient development board to evaluate the features and

performance of Microchip's PIC24 100 pin Micro-controller. The micro chip board

(PIC24) will be used to communicate with the GPRS module connected to the remotely

situated control room PC and then read three Analogue signals (inlet pressure, outlet

pressure, and flow) in a specific time interval and transmit them via built in GPRS to the

‘control room’ PC. Then Receive set point via GPRS from the ‘control room’ PC and

generate pulse-frequency-modulated signal according to the set point to the modulo22

.

As shown in figure 4-2 The board has an rs232 port and has two PCI slots where theadditional ports can be attached in order to receive three Analogue signals

35.




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Figure 4-2. Explorer 16 PIC24 100 pin development board 35

The micro-controller used in the electronic board is a PIC24FJ128GA010 micro-controller

that involves Analogue specifications of 36

:

10-bit, up to 16-channel Analogue-to-Digital Converter (A/D):

- 500 ksps conversion rate

- Conversion available during Sleep and Idle

Dual Analogue Comparators with Programmable Input/Output Configuration

4.1.4 Wavecom M1306B (GPRS Module)

The GPRS module will be used to transmit signals

from the PC to the microchip board in both the

ways22

. In order to transmit the pressure signals

received from the PRV to the control room PC and to

receive the calculated Control signal from the control

room to the flow modulated Modulo controller is to

be used ( figure 3-3). Here used- Wavecom M1306B

has a rs232 port to be connected with the control

room PC or with the Microchip board22

. Figure 4-3. GPRS module37




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4.1.5 Connection Leads (RS232 & Converters)

The rs232 cable will be used when connecting GPRS module to the “control room” PC.

When loading the programme to the microchip board, rs232 will also be used. The

converter is to be used when using the equipment outside laboratory and connecting itto non rs232 port computers

22.

Figure 4-4. RS232 cable38

Figure 4-5. RS232-USB converter 38

4.1.6 PCI cards (with RF connectors)

Use of The PCI cards is to be attached to the

microchip board when reading the signals

from the external signal generators those are

supposed sense the Inlet, Outlet pressure

and flow in the real system. These cards will

have RF port so that signals from the signal

generators can be sent to the microchip

board22

. Figure 4-6. PCI Card with RF connector 38




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4.2 SOFTWARE USED FOR THE PROJECT

Supervisory Control requires a software to operate that can be divided into proprietary

type or open type. Proprietary software are developed and designed for the specific

hardware and are usually sold together. The main problem with these systems is the

overwhelming reliance on the supplier of the system. Open software systems are

designed to communicate and control different types of hardware25

. Here in this project

a proprietary software has to be developed for the hardware being used. In order to do

so, the C programming language can be used and for the compilation and generation of

the developed software the applications required are described briefly bellow:

4.2.1 MPLAB Integrated Development Environment (IDE)

MPLAB Integrated Development Environment (IDE) is a free, integrated gcc-based

toolset for the development of embedded applications employing Microchip's PIC and

dsPIC micro-controllers. The MPLAB IDE runs as a 32-bit application on Microsoft

Windows and includes several free software components for application development,

hardware emulation and debugging. MPLAB IDE also serves as a single, unified graphical

user interface for additional Microchip and third-party software and hardware

development tools22, 39

.

4.2.2 MPLAB C30 (C compiler)

As, Both Assembly and C programming languages can be used with MPLAB IDE, this must

include a compiler that compiles written codes of C/C++. This C compiler is named

MPLAB C30 will be used to write the C programme for PIC24 micro-controller, compile it

and then upload it from computer to the microchip board. This will be available to

download from www.microchip.com for free22, 39

.




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4.3 HUMAN MACHINE INTERFACE

The goal of human-machine interaction engineering is to produce a user interface which

makes it easy, efficient, and enjoyable to operate a machine in the way which produces

the desired result. This generally means that the operator needs to provide minimal

input to achieve the desired output, and also that the machine minimizes undesired

outputs to the human. In a word HMI is the window to observe RTU from MTU25

.

Letting alone the Graphical HMIs those require high budget and design, simple HMI

system can be setup and programmed via a standard ANSI Terminal or terminal

emulator i.e. HyperTerminal that was previously included in various Microsoft Windows

operating systems (OS packages before Vista) or freely distributed terminal emulator

Teraterm25

.

In the project For the transmission of the set-point from the control room PC and for the

GUI supportive representation of the generated signal from microchip board to the PC it is

important to use some software to be working as the HMI for the emulation of these data.

And Tera-Term has been used for the purpose which is an open-source, free, software

implemented, terminal emulator (equalising interface of different systems) programme that

emulates different types of terminals, supports telnet, SSH 1 & 2 and serial port(RS232)

connections40

.

_______________________________

31Dennison R., SCADA System Assessment , Available at: http://www.epgco.com/scada-system-

assessment.html, Accessed: October 201032

Pressure Regulator, Available at: http://en.wikipedia.org/wiki/Pressure_reducing_valve 33

Figure taken from: http://webwormcpt.blogspot.com/2008/03/several-impact-of-backpressure-on.html 34

Modulo Flow Modulated PRV Controller, Available at:

http://www.industrysearch.com.au/Products/Modulo-Flow-Modulated-PRV-Controller-71462 35

Microchip Explorer 16 development kit, MachinGrid : robots at Work, Available at:http://www.machinegrid.com/2010/06/microchip-explorer-16-development-kit-hacks/ [Accessed at

11.41, on 17 December 2010]36

PIC24FJ128GA family datasheet, Microchip, pp- 0337

GSM modern Wavecom, Available at:

http://www.tradevv.com/chinasuppliers/gprsmodem_p_afc86/china-Gsm-modem-wavecom-Q2303A-

from-quot-HuTong-quot-products.html [Accessed at 12.30, on 17 Dec 2010]38

Ashok Karavadra, (2008-2009), Interim report for Final year project, Wireless Communication for

supervisory pressure control, pp- 0239

What is MPLAB IDE? , MPLAB Integrated Development Environment, Available at:

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en0194

69&part=SW007002 [Accessed at 13.16, on 17 Dec 2010]40

Tera-Term home page, Available at: http://hp.vector.co.jp/authors/VA002416/teraterm.html [Accessed

at 13.19, on 17 Dec 2010]

http://www.epgco.com/scada-system-assessment.html



http://en.wikipedia.org/wiki/Pressure_reducing_valve



http://webwormcpt.blogspot.com/2008/03/several-impact-of-backpressure-on.html



http://www.industrysearch.com.au/Products/Modulo-Flow-Modulated-PRV-Controller-71462


http://www.machinegrid.com/2010/06/microchip-explorer-16-development-kit-hacks/


http://www.tradevv.com/chinasuppliers/gprsmodem_p_afc86/china-Gsm-modem-wavecom-Q2303A-from-quot-HuTong-quot-products.html



http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en019469&part=SW007002



http://hp.vector.co.jp/authors/VA002416/teraterm.html

















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CHAPTER 5

IMPLEMENTATION

5.1 PROGRAMMING MICROCONTROLLER

The software that has to be developed for the hardware being used as mentioned in

chapter 4.2 using the C programming language along with the compilation and

generation technique of the developed software, the necessary steps are described

briefly with samples and figures in this section:

5.1.1 Receiving Analogue Signals

As per the specifically detailed architecture illustrated in figure 3-3 the workable

electronic fragment initialises its process with receiving three analogue signals from the

sensors to the PIC24 micro-controller working as the RTU. In embedded control, the

information from the analog world must first be converted to digital. The analog-to-

digital converter module is one of the key interfaces to the “real” world41

. In the case of

this particular project- an exemplary ADC is been presented to verify the conventional

programming principle of this conversion, so that it can be the way for the future

researchers to follow for obtaining the optimal technique needed for this project. A

voltage input has been read from the Explorer 16 Development board integrated

potentiometer in this section. The ADC module block diagram of PIC24 can be found in

APPENDIX A.

At first a new project has to be opened in MPLAB IDE with all the necessary pieces of

instruments installed from the attached CD-ROM or from the Microchip’s official web-

site. To create the new project for A/D conversion a source file named “pot.c” is been

created following the steps bellow:

In this Chapter

Programming Steps of Microcontroller.

Configuring HMI.

Additional Actions.

Difficulties Faced.




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1. Select “Project→Project Wizard” to activate the new project wizard

2. Select the PIC24FJ128GA010 device, and click Next.

3. Select the MPLAB C30 Compiler Suite and click Next.

4. Create a new folder and name it “ADC_sample”; name the project “ReceivingAnalogue Signal” and click Next.

5. Click Next to the following dialog box.

6. Click on Finish to complete the Wizard set-up.

7. Open a new editor window.

8. Type the following four comment lines:

/*** It’s an analogue world

** Converting the analogue signal from a potentiometer*/

9. Select “File→Save As”, to save the file as: “Pot.c”.

10. Select “Project→Save” to save the project.

Now the usual header file (p24fj128ga010.h) and the definition of a couple of useful

constants has to be defined. The first one ‘POT’ defines the input channel assigned to

the potentiometer and the second one ‘AINPUTS’ is a mask that will help to define which

inputs should be treated as analog and which ones as digital. The complete code

following the instructions of Lucio Di Jasio42

, appears bellow:

/*** It’s an analogue world** Converting the analogue signal from a potentiometer*/

#include <p24fj128ga010.h>#define POT 5 // 10k potentiometer connected to AN5 input

#define AINPUTS 0xffef // Analog inputs for Explorer16 POT and TSENS

void initADC( int amask){AD1PCFG = amask; // select analog input pinsAD1CON1 = 0; // manual conversion sequence controlAD1CSSL = 0; // no scanning requiredAD1CON2 = 0; // use MUXA, AVss and AVdd are used as Vref+/-

AD1CON3 = 0x1F02; // Tad = 2 x Tcy = 125ns >75nsAD1CON1bits.ADON = 1; // turn on the ADC} //initADC

int readADC( int ch){AD1CHS = ch; // 1. select analog input channel

AD1CON1bits.SAMP = 1; // 2. start samplingTMR1 = 0; // 3. wait for sampling time




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while (TMR1< 100); // 6.25 usAD1CON1bits.DONE = 1; // 4. start the conversionwhile (!AD1CON1bits.DONE); // 5. wait for the conversion to completereturn ADC1BUF0; // 6. read the cownversion result

} // readADC

void initADC( int amask){AD1PCFG = amask; // select analog input pinsAD1CON1 = 0x00E0; // automatic conversion start after samplingAD1CSSL = 0; // no scanning requiredAD1CON2 = 0; // use MUXA, AVss and AVdd are used as Vref+/- AD1CON3 = 0x1F02; // Tsamp = 32 x Tad; Tad=125nsAD1CON1bits.ADON = 1; // turn on the ADC} // initADC

int readADC( int ch){AD1CHS = ch; // 1. select analog input channelAD1CON1bits.SAMP = 1; // 2. start samplingwhile (!AD1CON1bits.DONE); // 3. wait for the conversion to completereturn ADC1BUF0; // 4. read the conversion result} // readADC

main (){int a; // initialisationsinitADC( AINPUTS); // initialise the ADC for the Explorer16 analog

inputs TRISA = 0xff00; // select the PORTA pins as outputs to drive the

LEDs

// main loopwhile( 1)

{

a = readADC( POT); // select the POT input and convert// reduce the 10-bit result to a 3 bit value

(0..7)

// (divide by 128 or shift right 7 timesa >>= 7;

// turn on only the corresponding LED// 0 -> leftmost LED.... 7-> rightmost LED

PORTA = (0x80 >> a);} // main loop} // main

Then, after adding the pot.c file to the ‘Source File’ and following programmer > select

programmer > 2. MPLAB ICD 2 steps- the programmer has been configured up ( figure 5-1).

Other than integrated MPLAB ICD2 there are external programmers i.e icd2 or PickiT 3 as

well, but MAPLAB ICD 2 has been used because it already is integrated in the Explorer 16

board. Later on the programe is to be programmed to the PIC following programmer >

programme and appear as in figure 5-2




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Figure 5-1. Programmer Setting




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Figure 5-2. Programming A/D Conversion Code




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Afterward, when Built the project following Project > Build All and, with successful

debugging via ICD2 debugging checklist, it is been programmed and been able to show

responses when playing with the on-board potentiometer (red marked in figure 5-3),

moving it from side to side while observing the LED index moving left and rightcorrespondingly. The results are illustrated bellow in figure 5-3.

Figure 5-3. LED position changing with potentiometer variation

As above, the very basic action taken in case of the PIC24 programming has illustrated its

workability on the principle of receiving analog signal from external stimulation and

processing the signal converting into digital and coming out with desired output. Since

the Supervisory pressure control project requires to receive and process a set of analog

data at its very first phase (Chapter 3.2), the principle of A/D conversion to be successful

acquires a very significant advancement on the way of fulfilling the project.




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5.1.2 Communicating with GPRS module

Once the PIC managed to receive analog signals from the pressure and flow sensors of

PRV section via the PCI card using RF connector and convert them into digital signal that

is transmittable through physical line, the necessity of transmitting that digital signalthrough RS232 came up, as in the project architecture it requires to be connected to a

GPRS module which is capable of transmitting signals wirelessly to the MTU- using RS232

serial connection ( figure 3-3).

Here the basic principle of transmitting on-board signal through the RS232 has been

demonstrated with example so that another one of the project fragments be trialed. In

embedded control, communication is equally a matter of understanding the protocols as

well as the characteristics of the physical media available. In embedded-control

programming, learning to choose the right communication interface can be as important

as knowing how to use it43

.

According to the PIC24 family datasheet there are two types of communication

peripherals available- synchronous and asynchronous35

. Here in this project the

asynchronous peripheral has been used as because Synchronous communication

peripherals need a physical line (a wire) to be dedicated to the clock signal, providing

synchronization between the two devices whereas in asynchronous communication

interfaces, there is no clock line needed, neither any physical connection; that is why

suitable for wireless communication43

.

PIC24 asynchronous serial communication interface modules are mainly UART1 and

UART2. To demonstrate the basic functionality of a UART (Universal Asynchronous

Receiver/Transmitter) peripheral the Explorer16 demo board has been used here where

the UART2 module is connected to an RS232 transceiver device and to a standard 9

poles D female connector35, 44

. This can be connected to any PC serial port or, in absence

of the “legacy interface” as mentioned above, to an RS232-to-USB converter device. In

both cases, the terminal emulation program Teraterm working as the HMI will be able to

exchange data with the Explorer16 board with a basic configuration setting. These are

known as the communication parameters. As a result of using the fast and convenient

configuration Wavecome M1306B, the GPRS module used here, the communication

parameters are:




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Baud rate : 115200 baud

Number of data bits : 8 data bits

Parity bit : No parity

Number of stop bits : 1 stop bit

Handshake protocol : Hardware handshake method using CTS/RTS

Now Using the “New Project Set-up” checklist to create a new project called “Serial” and

a new source file similarly called “serial.c” (process decribed at chapter 5.1.1) by adding

the useful I/O definitions needed to control the hardware handshake lines, the overall

code comes up as follows:

/*** Asynchronous Serial Communication** UART2 RS232 asynchronous communication demonstration code*/

#include <p24fj128ga010.h>// I/O definitions for the Explorer16

#define CTS _RF12 // Clear To Send, input, HW handshake#define RTS _RF13 // Request To Send, output, HW handshake#define TRTS TRISFbits.TRISF13 // Tris control for RTS pin

#define BRATE 34 // 115200 Bd (BREGH=1)#define U_ENABLE 0x8008 // enable UART, BREGH=1, 1 stop, no parity#define U_TX 0x0400 // enable transmission, clear all flags

void initU2( void){U2BRG = BRATE; // initialise the baud rate generatorU2MODE = U_ENABLE; // initialise the UART moduleU2STA = U_TX; // enable the TransmitterTRTS = 0; // make RTS an output pinRTS = 1; // set RTS default status (not ready)} // initU2

int putU2( int c){while ( CTS); // wait for !CTS, clear to sendwhile ( U2STAbits.UTXBF); // wait while Tx buffer fullU2TXREG = c;return c;} // putU2

char getU2( void){RTS = 0; // assert Request To Send !RTSwhile ( !U2STAbits.URXDA); // wait for a new character to arrivereturn U2RXREG; // read the character from the receive bufferRTS = 1;} // getU2

main(){char c; // 1. init the UART2 serial portinitU2(); // 2. promptputU2( ‘>’); // 3. main loopwhile ( 1)

{ // 3.1 wait for a characterc = getU2(); // 3.2 echo the characterputU2( c);




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} // main loop} // main

Now, after the normal process of building the project, activating the debugger and

programmer consecutively, generating the programme into the explorer 16 board and

connecting the serial cable to the PC with the teraterm terminal emulator configured

according to the requirements as shown in figure 5-4 & 5-5. In order to configure

teraterm the com port with which the RS-232 cable is been connected has to be

identified by checking “Device Settings” menu from control panel.

Figure 5-4. Selecting the COM port

Figure 5-5. Configuring Teraterm




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Once the terminal emulator is properly configured with the written programme

generated into the PIC the teraterm allows to type on the terminal keyboard while

echoing each character back to the terminal screen as illustrated in figure 5-6 bellow:

Figure 5-6. Transmitting character through RS-232

As it has been shown that the programme written enabled the PIC24 to echo the

entered character back to the terminal through RS-232 which also is the medium for this

project to connect the GPRS module to the RTU, thus the principle of communicating

with the GPRS module also been proven workable. Taking the approach as an example

furthure researchers may programme the best possible software that will work exactly

according to the requirement.




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5.2 ENABLING HMI

5.2.1 Terminal Set-up

Since the previous section (5.1.2) describes pretty elaborately the configuration of

Teraterm emulator software that is the assigned HMI for this project. For receiving the

transmitted data wirelessly at the control room PC working as the MTU and for

transmitting the data wirelessly from the PIC micro-controller working as the RTU to the

MTU the 2 way wireless medium requires 2 GPRS modules in both ends. Both the GPRS

modules acquire the same communication parameters thus the configuration for both

the devices are to be same.

5.2.2 Wireless communication

The supervisory control system requires receiving and transmitting set points and

instructions. So, the main principle of this transmission and receiving capabilities of the

GPRS module used as the wireless communicator can be shown by sending and receiving

data i.e. text massages using necessary appliances.

After connecting a GSM/GPRS modem to a computer, modem can be controlled by

sending instructions to it. The instructions used for controlling the mobile phone or

GSM/GPRS modem are called AT (Attention Terminal) commands45 which are also used

to control dial-up modems for wired telephone system. Dial-up modems, mobile phones

and GSM/GPRS modems support a common set of standard AT commands. In addition

to this common set of standard AT commands, GPRS modems support an extended set

of AT commands those can be used to control the sending and receiving of SMS

messages.

The very common AT commands those are often used for sending, receiving or saving

the text massage can be found in the Data sheet came along with the Wavecome

M1306B GPRS module that has been used throughout the project46

. Now, inserting a

properly networked SIM (Subscribers’ Identity Module) card into the GPRS modem and

connecting the modem physically to the computer that has a configured terminal

emulator using a specific COM port- the AT command for sending a text to a mobile is

illustrated in figure 5-7 bellow:




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Figure 5-7 Sending Text to mobile using AT command

In the Code - by typing AT command and getting “NO CARRIER” back at the beginning,

indicates the interruption in continuous wireless network and again in reply of the AT

command the reply “OK” means the network has been found at last and working

properly. Next, AT+CGMS=”+447876777440” indicates the

AT command assigned for initialising connection to send a

text to a specific number. Later on after a further delay

the “>” indicates the communication to be established

and been waiting for the massage to be typed. After

typing the massage and waiting for a moment came up

with the confirmation indication- “+CGMS: 56” that says

the text has been delivered in the 56th

memory position of

the cell phone46

. Thus the text been received as follows in

figure 5-8 .

Figure 5-8. Sent Text

using GPRS Modem




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Again, to demonstrate a two way communication wirelessly the system should be

capable of receiving data or text sent from another mobile. In order to do so, the AT

command set is been illustrated bellow in figure 5-9

Figure 5-9 Receiving Text from mobile using AT command

Here the computer has read a text message from the message storage area and with the

known index at which the SMS text message is located. In this case, +CMGR AT

command has been used. Here the typed command line indicates the unread SMS text

message is stored at index 1 and read it46

.

5.3 DIFFICULTIES FACED & CAUTIONS REQUIRED

A number of problems those have been encountered when programming the PIC micro-

controller, dealing with the GPRS module or configuring Teraterm.

Because of being in need of selecting the right device at first from the list of a

several nearly similar devices the PIC programming process may introduce some

hurdles.

The on-board switch that selects the activity of the board between PIC & PIM

requires always to be in the side of PIC when programming.

The compiler software that has been used to deal with this project is a Student

Version of MPLAB C30 compiler with a limited license permission which should

always bear in mind and should be working in the lab if compiler expires.




of 51

The right COM port must be identified when configuring the terminal emulator.

The existing connection is always supposed to be disconnected when dealing

with a new set of instructions in terminal emulator. The interruption may cause

unwanted and strange outcomes which can be confusing in practice. When playing with the GPRS module one thing has been observed that the GPRS

module does not support all the kinds of networks, so that if any one SIM card

turns out to be no working then its better not to be constrain with only one,

rather than trying another sim card from another network provider.

_____________________________

41Jacio, L. D,(2007), Chapter 10: It’s an analog world, Programming 16-bit Micro-controllers in C: Learning

to fly the PIC24, Newnes Publication, Oxford, UK, pp- 141

42Jacio, L. D,(2007), Chapter 10: It’s an analog world, Programming 16-bit Micro-controllers in C: Learning

to fly the PIC24, Newnes Publication, Oxford, UK, pp- 143

43Jacio, L. D,(2007), Chapter 07: Communication, Programming 16-bit Micro-controllers in C: Learning to

fly the PIC24, Newnes Publication, Oxford, UK, pp- 89-91

44Jacio, L. D,(2007), Chapter 08: Asynchronous Communication, Programming 16-bit Micro-controllers in C:

Learning to fly the PIC24, Newnes Publication, Oxford, UK, pp- 109-115

45How to Send SMS Messages from a Computer / PC?, Available at:

http://www.developershome.com/sms/howToSendSMSFromPC.asp [Accessed at 17.03, on 19 May 2011]

46AT Commands Interface: version 8.1, Chapter 9: Short Massage Command, Wavecom Ltd. Pp- 48-65

http://www.developershome.com/sms/howToSendSMSFromPC.asp






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CHAPTER 6

ANALYSIS AND DISCUSSION

Connecting Supervisory Control System wirelessly may carry on the vulnerability of a

wireless network. Communication between devices can be easily intercepted and

altered especially if it is not encrypted. Outsiders may gain control of the wireless

network and control the devices. Also wireless network are less stable compared to

wired network. One may ask why it is needed to connect on wirelessly even though

there are a lot of issues surrounding it. The answer is, as per the applicative

understanding25

it is because of many advantages it presents.

Wide area connectivity and pervasiveness

Routable Connectivity

Easy to expand

Redundancy and Hot Standby

Large addressing range

Integration of IT to Automation and Monitoring Networks

Additionally, in case of implementation of the model programme important points to be

emphasised on are:

Using Unified baud-rate in all phases.

Being instrumental and keep practicing on various coding techniques.

Staying precise regarding the time management.

Not being constrained only on the given documentations.

In this Chapter

Discussion on security issue.

Analysing limitations and advantages in brief.

Prominent bits of implementation.




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CHAPTER 7

SCOPE FOR FUTURE RESEARCH

As per it has been said in the very beginning of this project that, to give the future

researchers a complete guideline of taking this project further to the optimal level is the

most important motto determined, there is no need to say that this particuler project

involves a huge possibility of furthur advencement.

The variables received from the sensors can not only be converted and

trnsmitted but also the signals may be received in a specific strigned order.

The serial communication may be taken advanced to transmit multiple data

strings and conveying them consequently.

The GPRS communication may not only be communicating in duplex but also

being able to connect to the internet for more flexible connectivity and at the

same time the System network can be pin protected for better safety reason.

The technique of data acquisition can be developed further and can turn into a

more accurate method of calculating set-point in the Master Terminal Unit to be

transmitted to the RTU which will provide the Modulo a set point to control the

PRV.

In this Chapter

Lacks of the present design.

Chances of improvement.




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CHAPTER 8

CONCLUSION

Wireless Supervisory control system is required in those applications when wireline

communications to the remote site is prohibitively expensive or it is too time consuming to

construct wireline communications. In particular types of industry like Oil & Gas or Water &

Wastewater, wireless supervisory control system is often the only solution due to the

remoteness of the sites. Wireless supervisory control system replaces or extends the fieldbus to

the internet. It can reduce the cost of installing the system. It is also easy to expand. In this paper

an architecture of whole system in wireless mode has been described. The transmission of

communication through the internet, its advantages and disadvantages are also discussed.

So to conclude, it can be said that, the project for designing and implementing a

wirelessly connected supervisory pressure control system has been so far completed

with an excellently clear conventional architecture been demonstrated and with a very

basic overview of being practically developed. In the first phase of describing the ideal

architecture of a wirelessly communicated supervisory pressure control system all the

components along with their on-field applications have been described. Later on in the

development phase the basic principles of all the bits and pieces of wireless supervisory

control system has been described and demonstrated figuratively that, turn this report

into a valuable guideline for the further students or researchers.




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BIBLIOGRAPHY

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Publication, Oxford, UK,

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APPENDIX A

Figure A-1. ADC Module block diagram

Figure A-2. Asynchronous Serial interface block diagram




Figure A-3. Simplified UART modules block diagram

Figure A-3. The UxMODE control registers.

Fi A 3 Th U STA t l i t

wireless communication system for supervisory pressure control

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