Building Management System- Revised

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BUILDING AUTOMATION SYSTEM
QANDEEL RAZA SHAHID SYED MUHAMMAD ALI HAMID ASHRAF CHEEMA

Department of Electrical Engineering

COMSATS INSTITUTE OF INFORMATION TECHNOLOGY
WAH CANTT – PAKISTAN
Session 2009-2013

PROJECT BRIEF
PROJECT NAME BUILDING MANAGEMENT SYSTEM

UNDERTAKEN BY

QANDEEL RAZA SHAHID SYED MUHAMMAD ALI HAMID ASHRAF CHEEMA

SUPERVISED BY

MR. ATIF AMIN

INTERNAL EXAMINER

EXTERNAL EXAMINER

STARTED ON

FEBRUARY 2012

COMPLETED ON

JANUARY 2013

DATE

Abstract
Building automation systems (BAS) provide facility managers with the ability to monitor, track, and respond to the performance of facility assets. Round the clock monitoring ensures that all systems function optimally. Appropriately managed building automation systems increase facility assets reliability and reduce maintenance costs. Large organizations can achieve economies of scale by centralizing facility asset monitoring.

TABLE OF CONTENTS
1 Building Management System ..............................................................................................................1 1.1 1.2 1.3 1.4 1.5 Description ..............................................................................................................................2 Block Diagram...........................................................................................................................3 BMS Introduction .....................................................................................................................4 History .....................................................................................................................................5 Benefits of BMS .......................................................................................................................6 1.5.2 1.5.2 1.5.3 1.5.4 1.5.5 1.6 1.6.1 1.6.2 1.6.3 1.6.4 1.6.5 1.6.6 2 2.1 2.2 2.3 Building Management ..............................................................................................6 Enhancing Staff Productivity ....................................................................................6 ReducedOperating Cost ...........................................................................................6 Increased Reliability of Plants and Services .............................................................7 Protection of People and Equipment .......................................................................7 Installation -Management and Control Functions ...................................................8 Energy-Management Functions ...............................................................................8 Risk-Management Functions....................................................................................9 Information-Processing Functions ...........................................................................9 Facility-Management Functions ...............................................................................9 Fault Detection and Diagnosis, Maintenance Managament..................................10

Functions of BMS......................................................................................................................7

Sensors ...............................................................................................................................................11 Lighting Control Systems ........................................................................................................12 Purpose of Lighting Control Systems......................................................................................12 Basic Components of Lighting Control Systems .....................................................................13 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.4 2.4.1 2.4.2 Lamps .....................................................................................................................13 Ballasts and Dimming Ballasts ................................................................................13 Dimmers .................................................................................................................14 Analogue Control and Digital Control ....................................................................15 Sensors and Control Devices ..................................................................................15 Passive Infrared Sensors (PIR) ................................................................................17 Ultrasonic Sensors ..................................................................................................18 2.4.2.1 2.4.2.2 2.4.3 Fundamental Utrasonic Properties .....................................................18 Speed of Sound in Air as a Function of Temperature .........................18

Motion Sensor ........................................................................................................................16

Microwave Sensors ................................................................................................20

2.4.3.1 2.4.3.2 2.5 2.6 3

Design..................................................................................................20 Drawbacks of Microwave Sensors ......................................................21

Door Switch ............................................................................................................................21 Light Dependent Register (LDR) .............................................................................................22

Programmable Logical Controller (PLC)...............................................................................................23 3.1 History ....................................................................................................................................24 3.1.1 3.1.2 3.1.3 3.2 3.3 The First Programmable Controller........................................................................24 The Conceptual Design of PLC................................................................................25 Today's Programmable Controller .........................................................................25

Programmable Controllers and the Future ............................................................................26 PLC Applications .....................................................................................................................26 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 Chemical/Petrochemical ........................................................................................27 Manufacturing/Machining .....................................................................................27 Power .....................................................................................................................27 Mining ....................................................................................................................27 Food/Beverages .....................................................................................................27 Micro PLCs ..............................................................................................................29 Small PLCs...............................................................................................................29 Medium PLCs ..........................................................................................................29 Large PLCs...............................................................................................................29 Ease of Installation .................................................................................................30 Ease of Maintenance and Troubleshooting ...........................................................30 Processors ..............................................................................................................32 3.6.1.1 3.6.2 3.6.3 3.6.2.1 3.6.3.1 3.6.3.2 Processor Scan .....................................................................................32 The Input Voltage.................................................................................33 Memory Section...................................................................................34 Memory Structure and Capacity ..........................................................34 System Power Supply .............................................................................................33 Memory Overview..................................................................................................34

3.4

PLC Product Application Ranges.............................................................................................28 3.4.1 3.4.2 3.4.3 3.4.4

3.5

Advantages of PLC ..................................................................................................................29 3.5.1 3.5.2

3.6

PLC Components ....................................................................................................................31 3.6.1

3.7

Programming Device ..............................................................................................................35 3.7.1 3.7.2 Mini-Programmers .................................................................................................35 Personal Computers ...............................................................................................36

3.8

The Role of PLC .......................................................................................................................37

3.8.1 3.8.2 3.9 3.9.1 3.9.2 3.9.3 3.10 4

Input Devices ..........................................................................................................37 Output Devices .......................................................................................................37 Ladder Diagram and the PLC ..................................................................................38 Ladder Diagram Format .........................................................................................39 Ladder Relay Instructions .......................................................................................39

Introduction to Ladder Programming Languauge ..................................................................38

Timers and Counters ..............................................................................................................41

Project Related Trilogy PLC..................................................................................................................42 4.1 Introduction............................................................................................................................43 4.2 4.3 Simulator ................................................................................................................................46 PLC based Project Work .........................................................................................................47 4.3.1 4.3.2 4.3.2 4.4 4.4.1 4.4.2 4.4.3 4.4.3 Motion Sensor ........................................................................................................47 Door Switch ............................................................................................................47 LDR .........................................................................................................................48 Remote Terminal Units ..........................................................................................49 Master Terminal Units ...........................................................................................49 Modbus ..................................................................................................................49 RS-232 ....................................................................................................................50

Communication Module.........................................................................................................49

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GSM .....................................................................................................................................................53 5.1 GSM History............................................................................................................................54 5.2 5.3 5.4 5.5 5.6 Mobile Station ........................................................................................................................54 Base Station Subsystem .........................................................................................................55 5.3.1 ABIS Interface .........................................................................................................55 The Base Station Controller....................................................................................................55 Architecture of the GSM Network .........................................................................................56 SMS Through Hyper Terminal ................................................................................................57 5.6.1 5.6.2 5.7 5.8 5.9 5.10 SMS.........................................................................................................................57 Hyper Terminal .......................................................................................................57

Introduction to AT Commands ...............................................................................................57 General Syntax of Extended AT Commands ..........................................................................60 AT Commands for SMS Text Mode ........................................................................................62 GSM Project Work .................................................................................................................63

6 Code Listing.........................................................................................................................................65 Bibliography and References .....................................................................................................................70

CHAPTER 1

BUILDING MANAGEMNET SYSTEM

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1.1 Description
There are some inputs like Motion Sensor, LDR, Lights, Fans, AC and Door Switches. These inputs are connected to the PLC. GSM Module is also connected with PLC as an input. One can ON and OFF the lights and fans manually also. First the motion sensor is enabled through SCADA system. When it detects the motion then lights are ON for 5 mints. Then after 5 mints lights are OFF. We can enable the motion sensor with our requirements. For example in the day, we can enable only two motion sensor which only on two lights with the detection of motion. Door switch is used for data logging. If door is opened then it store date and time of door opening and when door is closed then the date and time of door closing is also stored in the PLC memory. Then there is a GSM module which is connected with PLC. There is enable/disable internal relay. When on make it enable through SCADA system, then after the detection of motion, the message is sent to the specific person. This is used for security purpose. It also tells the room in which motion was detected. The another portion of GSM is that we can ON/OFF the AC. When we send the message through mobile then it goes to the PLC memory through GSM module. The GSM module is connected with PLC via RS-232 serial communication port. Then PLC check that message. If the message is wrong then PLC send the message to the mobile user as “Command Error” and if message is correct then PLC turn the AC ON/OFF. There is a SCADA system which is attached with PLC through RS-232 communication port. SCADA system is a programming tool, which is installed in the PC. One can control all the devices through SCADA programming tool.

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1.2 Block Diagram

SCADA

RS-232

Lights, Fans, AC switches Lights, Fans, AC etc. Motion Sensor

LDR’s

PLC
Security System

Door Switches

Rs-232

GSM Module

Mobile

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1.3 BMS Introduction
The BMS is central controlled system that is spread throughout the building and interfacing many other devices. The BMS controls, monitors and optimize many building services like lightening, heating, ventilation, fire alarms and other security systems. So optimizing these services results the energy saving. It consists of software and hardware both. The software program which is written in hierarchical manners and this software can be the proprietary, using these protocols C-bus, Profibus etc. There are also vendors which provide the open standards like BACnet, Modbus, DeviceNet, and LonWorks etc. An efficient building management system brings convenience in our lives. Using BMS our dayto-day comforts are controlled so that we can experience the right heating and lighting. The Intelligent Building Management System provides direct access to the global information and technology for both work and leisure. Windows and Doors are monitors with the help of Building management system. Advanced alarms systems detects the intruders and send out the call to the specific person. An effective building management system can save energy and drives down the cost. An individual room control can save 30% cost on heating and cooling.

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1.4 HISTORY
The earliest automatic control device happened in 270.B.C. The figure given below shows the water clock device.

Rene-Antoine Ferchault de Reaumur had given some ideas of temperature control. Automatic control of steam engine and many attempts on this engine to improve its efficiency also helped on automatic control system in general. In near 1900’s the electricity began playing a part in automatic control systems. Elmer Sperry developed first PID-type control. In 1911, this type of PID control was used in ship steering. Then the Foxboro instrument company invented the pneumatic “flapper nozzle amplifier”. The control law that we commonly associate with the modern PID loop basically came from Nicholas Minorsky. In 1922, he noticed the helmsman and introduces the integral, proportional and derivative type of control same as we are using today.

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In the 1920’s many instrument companies made the complete boiler system. During the 1930’s, Foxboro instrumental company began making improvements in flapper nozzle systems. At that time controllers were very expensive. In 1936, the first organization was made named as industrial instruments and regulators committee. The goal of this organization was to standardize the control design methods and terminology. During 1940s to 1950s, different companies started to improve their products. For example, the Foxboro Company improved controller that was field adjustable. From the 1930s to 1950’s, it was the brilliant time for the electrical and electronics which led to the early systems of weapons, communications and semi-conductor circuitry. Due to small-scale electronics, affordable computers were introduced in the market and those computers were constantly evolved from 1950’s to till now. BMS as a phrase introduced in early 1970’s. there were also other phrases used for building management referred as building automation system (BAS) or energy management system (EMS). It was the advent of “MODEM”(modulator-demodulator), which converts analog signal into digital signal so that communication can be carried out over a long distances, that led to the latest building management systems.

1.5 Benefits of BMS
The typical benefits of BMS are given below

1.5.1 Building Management
BMS gives the most cost-effective means for staff to manage the building. It means that monitoring the conditions and maintaining them at the required level at any time. It also means that it respond quickly and efficiently to changes in function patterns.

1.5.2 Enhancing Staff Productivity
The BMS also provides the benefits which are less tangible and difficult to measure. These increased the efficiency of personnel because these improved environmental conditions. Moral and job satisfaction are also improved.

1.5.3 Reduced Operating cost
One of the major expenses in operating a building is the energy cost which is used for heating, air-conditioning etc. BMS is the key function to reduce the energy cost as much as possible. The BMS reduces the manpower requirements which can have a major effect on annual cost. All the types of buildings contribute in some kind of energy saving system. The system which is installed only to save energy is referred as building energy management system (BEMS) or energy management and control system (EMCS) rather than BMS. But EMCS or BEMS
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considered as a part of BMS. Through EMCS or BEMS the building services can be monitored and controlled which is a significant contribution to the energy consumption of buildings.

1.5.4 Increased Reliability of Plants and Services
The purpose of system operation and maintenance are to ensure that plant runs properly. Failure of components always results in more expensive repair. So the failure component required the periodic attention. Furthermore, the breakdown of certain equipment interrupts the services which results the owner loss. A BMS can make a significant contribution by monitoring systems continuously and providing preventative maintenance. When a equipment degraded to a certain level then the alarm system is activated which can be in terms of sms, call to specific person etc.

1.5.5 Protection of People and Equipment
There is a communication network of BMS which put to work sending alarms to an operator or specific person in the case of smoke, fire, intrusion or any situation which can damage the equipment. In addition the BMS can also help on other security measures. For example, the BMS can help as a guard against intrusion in the building by utilizing card access so BMS can controls and monitors specified areas of the building so that the intrusion can be caught.

1.6 Functions of BMS
A building management system is a tool that enhances the capabilities of the responsible operations of the building. The functions of typical BMS are given below:

      

Installation-management and control functions; Energy-management functions; Risk-management functions; Information-processing functions; Facility-management functions; Performance monitoring and diagnosis; Maintenance management;

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1.6.1 Installation-Management and Control Functions
Direct digital control (DDC) is common terminology used in computer field. This concept of DDC is used to automate a building. DDC changed the traditional analogue systems into digital systems which changed the nature of the building. The control rooms with DDC capacities have played a significant role in building management system. Control functions of BMS are divided into two parts:   Local control functions Supervisory control functions

Local control functions are basically provides the permission to the building services so that they can work properly and it also provides sufficient services in the building. Local control functions are also subdivided into two parts:   Sequencing control Process control

Sequencing control shows the conditions and orders related with bringing the equipments online or moving them offline. In building management system, sequencing control consist of chillersequencing control, light on/off control, fan-sequencing control etc. Process control is used to adjust the control variables so that accurate results can be achieved. The typical process control in building systems includes temperature control, air and water flow rate control and pressure control. For building processes, common feedback control functions are proportional integral derivative (PID) control, step control and modulating control etc.

1.6.2 Energy-Management Functions (supervisory control)
With the improvement of energy management in a building savings can be brought provide the economical situation for purchasing the systems. The different ways through which energy can be saved grouped into two parts. The first is starting and stopping the plants in a correct or optimal timings which results energy saving. The second is running plants in energy-efficient conditions which results the energy saving. One can not turn off equipment which is needed constantly, so we need to turn off and on the equipments without compromising the quality of services and indoor environment. There are two better ways to starting and stopping the equipments in energy-efficient way. These are known as “scheduled” and “optimized” start/stop. The HVAC and lights can be turned off/on using the combination of clock and calendar that is scheduled start/stop. The BMS checks the existing conditions and the conditions for the next several hours and after that BMS decides that when to start and stop the system that is optimized start/stop. Normally the supervisory control is considered the optimal control, to minimize or maximize the real function by choosing the variable values within allowed ranges. The difference between
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supervisory control and local control is that supervisory control interacts among all the components and their related variables and it also gives the overall system level characteristics.

1.6.3 Risk-Management Functions
As the BMS detects temperature and humidity in HVAC system, similarly, it can also detects fire or smoke. BMS is integration of fire safety which provides personnel safety instead of using two independent systems. The BMS can open and close the fire doors, start/stop some fans and pressurize some building parts. So it can help to prevent the spread of fire and also can reduce the spread of smoke. Security system in BMS provides greater security and reduces the risks. Motion sensor on doors and windows sensed the presence of someone who enters through unauthorized way. So through PLC, the detection can be reported to the central computer and PLC also sends the sms to the specific person. This SMS even tells the exact position of the intruder.

1.6.4 Information-Processing Functions
It is not simple to evaluate the performance and economy of large BMS and it can not also absolutely precise. The basic data which is required for economic evaluation is the total cost of BMS and economic benefits which comes from the BMS. The BMS initial cost can be determined easily and more accurately rather than the savings from energy conservations. The powerful systems monitor the energy consumptions and then make the graph/table which makes to estimate easily. Engineers can monitor energy use and energy cost and also checks the performance of BMS using computer simulation techniques and software. So through BMS, a financial report can be produced easily.

1.6.5 Facility-Management Functions
Facility management can have broad definitions. BMS functions are part of FM functions. Building management systems are the systems used to achieve the facility management functions. Intelligent buildings require the facilities management which defines the requirements and deliver benefits. On the other hand, building managers requires the intelligent building so that building performance and many other services can be controlled easily and efficiently. So, according to this point of view, the facilities management is basically to ensure that all the services are working properly. While according to the building services engineers, FM functions are building facilities and building spaces. Facilities management can be achieved through building management system. Hence the facilities management requires the combination of integrated BMS and traditional information management system. For quality and efficient management, most of the managers and owners require large amounts of data of different types.

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Now days, different software tools are used in the facilities management systems such as NetFacilities, ARCHIBUS/FM etc. These softwares provide information management platform which can be web-based, computer-based space management, work-order administration etc. This software gives the real time collaboration. Practically, many facilities management systems still give the single information management systems. Due to the huge data store, these systems cannot get data form integrated building management systems. In the future, the computer aided facilities and maintenance management systems should provide more efficient management tools.

1.6.6 Fault Detection and Diagnosis, Maintenance Management, Automatic Commissioning
In modern building management systems, effective maintenance is important task. The effective maintenance increases the equipment life, keep equipment in proper condition and also increase the equipment efficiency. It is important for intelligent building like BMS which have many complex facilities. Smart maintenance based on data monitoring. Data monitoring provides information about the equipment condition. Conventionally, maintenance has been done according to schedule which may be not suitable in all cases. Information guided maintenance basically gives the services when it is needed. So information guided maintenance saves the manpower and also reduces the risks. FDD technologies are used as online or offline. Offline process based on recorded monitoring data. Online process is advanced technology, which detects faults when system is running and also produces a report. Further development of FDD technology is automatic commissioning. It not only detects faults online but also reflects the analysis results to the system for better control.

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CHAPTER 2

SENSORS

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2.1 Lighting-Control Systems
The places for living, working or for other uses, where there are no sufficient daylight available, artificial lights play important role on these places. There are some special places where lights play a dramatics or dynamic environment like theatres and other entertainment places. Lightingsystem consumes major energy in the building like HVAC system in offices and commercial buildings. The energy consumption of light and their quality depends upon the types of lamps, the architectural view and the control.

2.2 Purpose of Lighting-Control Systems
Daylight conditions and the spaces of uses are changing day-by-day. So lighting-control system requires the following purposes which can be operated manually or automatically.      Energy saving Visual comfort Functional need and Flexibility of space Requirements of legislation To create dynamic or dramatic environment

Different functions or activities require different visual environment. For example, in lecture hall, there is running a power point presentation so, it need the low luminance during presentation so that the audience can see the presentation clearly and comfortably. And if there is no presentation and lecture is on speaking then it requires high level of luminance for pleasant and effective communication. Similarly, if audience enters in a movie theatre then lights should be on so that they can find out there seats but when the movie starts then lights should be off so that audience can see the movie properly and clearly. So, different lighting-systems are required for different functions. Energy efficiency is very important topic related with lighting-control systems. Lighting-systems consume a great portion of building energy. Energy used by lighting-system can be reduced by providing in the areas where the light is needed and providing the right level of lighting. So, the main control functions for this purpose are on/off switching and dimming. Lighting plays a major role to providing comfortable environment in working and living places. In residential buildings, it also affects the satisfaction of occupants. It also affects the productivity of occupants. Different people require different level of lighting. In some countries, light has become a subject of legislation. Major topics are: setting standards for different activities to show its effectiveness; setting standards for the sake of safety and security; setting standards to use latest lighting technologies for energy efficiency. Although energy management is playing great role but creating a beautiful effects of spaces in fashion has become the major driving force. Light systems can be controlled by balancing
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different light sources or by the change between one light state and the other for the pleasant environment. Lighting systems can be controlled to provide relaxation and pleasant visual environment. Lighting systems can also be controlled for dynamic environments.

2.3 Basic Components of Lighting-Control Systems
     Lamps Ballasts and Dimming Ballasts Dimmers Analogue Control And Digital Control Sensors and Control Devices

2.3.1 Lamps
Typical lamps are used as general purposes like tungsten halogen lamps, fluorescent lamp etc. Other lamps are like high intensity discharge lamp (HID), high pressure mercury lamps, metal halide lamps, xenon lamps and the lamps for special purposes. Artificial electric lighting started in 1870’s when the incandescent lamp was invented. It was the main electric light source until today’s applications are more competitive light sources. Even today, it is using in many home applications. Fluorescent lamp belongs to the family of discharge lamp. The function of discharge lamp is that light is produced by electrical discharge within the gas. The main type of fluorescent lamps is the straight tubular lamps which are using most commonly today. The features of fluorescent lamps are high efficiency and long life. Now a day, electronics industry is developing rapidly due to which fluorescent lamps are available in very small size. Due to this latest electronics, the lamps and other electronics components are integrated as compact fluorescent lamps. Compact fluorescent lamps are widely using nowadays in special lamps and also in traditional applications of incandescent lamps.

2.3.2 Ballasts and Dimming Ballasts
Ballasts are used to control the starting and operating voltages of discharge lamps like fluorescent lamps, HID lamps etc. Ballasts are used to limit the current which can be simple resistor or complex electronic device (like electronic ballasts). Ballasts have negative resistance so they are very necessary for discharge lamps. Negative resistance means that discharge lamps are unable to limit the current that passes through them. So ballast must control the current flow rather than lamp can be failed. Electromagnetic ballasts work on the electromagnetic induction and this induction provide the starting and operating voltages to the gas discharge lamp.

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Electromagnetic ballasts just only limit the current but do not change the frequency of input power. So the lamp illuminate on each half cycle of the power supply. That is why, fluorescent lights flitter visibly. Latest ballasts are electronically not electromagnetically. In the electronic ballasts voltages are transformed by using solid state circuitry. And the electronic ballast can also change the frequency of power supply while electromagnetic ballasts can not do this. So that’s why electronic ballasts can greatly reduce or illuminate flicker in the lamp. Electronic ballasts are more efficient and they can also work on low temperature. Dimming ballasts are for both linear and compact fluorescent lamps. Benefits of dimming fluorescent lamps are given bellow:     Flexibility: allows the lighting systems that they can work on different activities for different functions. Energy saving: saves the energy and also reduces the load in the peak demand periods. Higher comfort: by controlling the light level at desired ranges, satisfaction and comfort can be achieved. Increased lamp life: in specific applications where instead of frequently on and off, by dimming the lamps, lamps life is increased.

Dimming ballasts range is 25-100 per cent, 10-100 per cent, or 5-100 per cent. So by choosing one of them, energy can be saved. Different type of applications requires different dimming range like a 3-100 per cent or 1-100 per cent. Dimming ballasts are divided into two parts:   Analogue electronic dimming ballasts Digital electronic dimming ballasts

The common analogue method is 0-10V DC as the control input to the dimming ballast. Digital electronic dimming ballast includes microprocessor and other components. It receive, store and send the information. Microprocessor receives the signal, stores the address of ballast and sends status information. Both digital and analogue ballasts control the output of lamp which is depend on control device. Ballasts are wired with the local and central points where the control signal is generated. This control signal can be generated manually or automatically. Analogue ballasts easily available in the market in lower price and available with a wide range of control devices. Digital dimming ballast gives the higher accuracy of control like it addresses individually, group the ballasts, take the gain feedback information from the ballasts and then make a flexible lighting system.

2.3.3 Dimmers
Dimmers are used to change the brightness of the lamps. By varying the voltage of the lamps, the brightness of the lamps can be changed. For this purpose, the dimmable ballasts of the fluorescent lamps are used to vary the output of lamps.

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Non-electronic dimmers are reactor dimmers, resistance dimmers and transformer dimmers. Modern dimmers are thyristors, transistors and silicon-controlled resistors. Dimmers are available in different size and capacity. Ordinary light switch is used for residential lighting and multiple channel units are used in theatre lighting or architectural applications. Modern dimmers are controlled by digital control system. Other dimmers are controlled through analogue or digital control. Analogue dimmers operate between 0-10V. They have a separate wire for each dimming channel so that they can receive a control voltage signal. While, there is a built-in microprocessor in the modern dimmers. Their working principle is that, they receive the control signal from controllers and then convert that signal into control signal for switches. They also have diagnostic feedback system and then they send that feedback to the controllers.

2.3.4 Analogue Control and Digital Control
In the earliest days, switches and light dimmers were operated manually. A knob was used to move a sliding contact or to make interrupt in the power supply. Today, analogue and digital control are the basic elements for remote or automatic control. Analogue is a simple control for automatic or remote control of dimmers. There are different ways to control the lights. Nowadays, there are two standard ranges for light-controlling system: 1-10V and 0-10V. 0-10V is generated by Entertainment Services and Technology Association (ESTA) in United States. All the entertainment dimming devices follow this protocol. 1-10V is an extension of analogue control standard IEC 60929. This standard is used for control ballasts of fluorescent lamps. This control range of voltage ensures that electrical noise does not affect the control performance of system. Before the LAN based digital system, there were some systems that used a multiplexed analogue control. They used one wire to control multiple dimmers. But today, this technology is terminating gradually. Digital control technology using a network concept is using today. Analogue control is still using widely in light controlling system for sensor signals and control signals. Digital control is used for lighting system on large scale.

2.3.5 Sensors and Control Devices
Light sensors are used for automatic control of light systems. Level of light is measured through the light sensors for dimming or switching the lights. There are different types of light sensitive materials. Nowadays, silicon photo-diode is used as a light sensor. It is used in photovoltaic mode that is coupled with an amplifier and then give the proportional output or a digital signal through which relay is operated.

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Light sensors give analogue or digital output for the controllers. Light sensors are designed in such a way that provides 1-10V analogue output through which electronic ballasts are controlled. Some light sensors are designed to provide on/off output through which switch is controlled. Light sensors are coupled through communication interface so that measured output can send to the controllers through control network.

2.4 Motion Sensor
Electronic motions sensors are the sensors which detect the motion and convert that detected motion into electric signal. A motion detector can be connected to the burglar alarm for security purpose or it can be used to control the lights such occupancy sensors. There are three types of motion sensors: • Passive Infrared Sensors (PIR) • Ultrasonic Sensor • Microwave Sensor

2.4.1 Passive Infrared Sensors (PIR)

It is a device which detects the infrared energy emitted from any object like human body. PIR is not like normal optical sensor which includes LED transmitter and IR receiver to emit energy. PIR does not emit any type of radiation. As mentioned with it name “Passive” which shows that it can sense the energy not radiates. Human body is a common object which is sensed by PIR sensor, so this sensor is normally used in automatic light switches, door openers etc. Anybody which has temperature above absolute zero radiates infrared energy. A human eye can not see this infrared energy but pyroelectric material only can sense this energy. This material is pasted on the core of the PIR sensor. When it is sensed the infrared energy then it generates a small amount of electric charge. Then there is an amplifier which amplifies the small amount of
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voltage generated by the Pyroelectric material. Then this voltage is sent to a comparator. It looks the difference between initial reading of signal and the final output. Sometimes PIR sensor fails to sense the IR energy like a reflection of objects during hot sunny days or flash of bright light. But there are many techniques which can solve these problems. First method is that human body radiates infrared energy at the wavelength of 9 to 10um. So the infrared filter is placed in front of PIR sensor which allows passing the infrared waves within the wavelength 10 to 14um. Second method is that a Fresnel lens is placed in front of PIR sensor. It performs two types of functions. First, it focuses the infrared energy onto the sensor which is emitted over a wide area. Second, it divides the area into hot and cold zones. So when a person walks across the sensor, so infrared value is being changed. So it produces varying output signal from the sensor which shows a motion. Then the comparators works on this changing output and respond to this signal. The items that don’t move like heaters and lights do not generate the variation in output. So the comparator does not respond these constant infrared sources.

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2.4.2 Ultrasonic Sensors

These sensors transmit the ultrasonic waves towards the target and target reflects the sound back towards the sensor. So the system measures the time interval between sending the waves and receiving the echo and then system compute the distance to the target with the help of speed of sound in the medium. So normally these sensors are used for distance measurement. There are many types of ultrasonic sensors available in the market based on environmental sealing, electronics features and mounting configurations. These sensors operate on different frequencies so they have different radiation patterns.

2.4.2.1 Fundamental Ultrasonic Properties
Ultrasonic sound wave frequency is greater than 20 kHz which is above the human hearing frequency. Transducer is device which is used to transmit and receive the ultrasonic sound. Normally this device is used in loudspeakers and microphones. Normally a single transducer is used in ultrasonic sensors to transmit the ultrasonic sound towards the target and to receive the reflected echo from the target. Ultrasonic sensors operate on frequencies between 40 kHz and 250 kHz. Some fundamental ultrasonic properties are given below.

2.4.2.2 Speed of Sound in Air as a Function of Temperature
As we mentioned above that ultrasonic sensor transmit the ultrasonic sound and then receive the reflected echo. So some time is elapsed during this process. Then distance is computed through the medium which is normally air. The accuracy of distance is directly proportional to the accuracy of speed of sound which is used in calculations. So the actual speed of sound is function of composition and temperature of medium from which light passes.

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In the above graph, the speed of sound is plotted as a function of temperature.

• Wavelength of sound as a function of sound speed and frequency
As the speed of sound and frequency changes, the wavelength of sound changes. This expression given below.
λ = c/f λ = wavelength ; c = speed of light ; f = frequency;

The graph which is given below shows the wavelength of sound as a function of frequency at room temperature.

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2.4.3 Microwave Sensors

Microwave sensor radiate microwave energy which spread throughout the detection area same as ultrasonic sensor works. There is a gun diode which emits the energy ranging in x-range and it is similar with the effect to the Doppler frequency shift. So any movement in the detection field may be activating the alarm system. This sensor does not affect the humans and pacemakers.

2.4.3.1 Design
These motion sensors have two types • Mono-static: The system in which emitter and receiver lies in one unit • Bi-static: The system in which emitter and receiver contains separate units. Mono-static units defined the area of detection. This area of detection depends upon the emitted microwave beam. The range of detection is up to 400 linear feet. One can configure the beam for a particular situation by making long, short or narrow the beam. Whereas the detection range of bi-static sensor is larger than mono-static sensor which is up to 1500 linear feet. While, this sensor does not allow the user to configure its detection area as precisely as the mono-static sensor. These sensors radiate alternating frequencies, activating and deactivating rapidly, followed by the deactivation of the receiver. So the unit noticed these time intervals to detect motion. Time intervals define the periods through which motion is detected by the receiver, known as Cut-Off region. There is the

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programming mode in the mono-static sensors which allow that motion can be detected only in the specific time periods.

2.4.3.2 Drawbacks of Microwave sensors
Microwave beams can penetrate through some type of materials but can not penetrate through the metal. So it means that sometimes sensor can not detect the motion on desirable place while sometime it can detect the motion where it is not desired. As microwave beam can not pass through the metal so, when there is metal sheet in front of sensor then it can not detect the motion behind the metal. While as from some materials, this beam can penetrate. So microwave beam pass from a wall so it can detect the motion behind the wall and this wrong detection may be cause the false alarm. Even though, it can detect the fluorescent light, which emits detectable lights particles, that can be cause the false alarm.

2.5 Door Switch

The protection for all the working production halls is most important at all the times. Door sensor is a switch which can which can detect the opening of door or window. The principle of working of all the doors and window is same, no matter how sophisticated. The switch is mounted towards the door or window and there is a magnet which is attached with the window or door frame. When door or window moves away from the magnet then the switch opens and vice versa. And on the basis of opening of switch alarm is activated. So in our project, when a door is open or close then data logging is activated. In the data logging, time and date are saved during the opening and closing of the doors in the specific given time. We are using the door switch made by AH Automation.

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2.6 Light Dependent Resistor (LDR)

These sensors are specially used to sense lightness or darkness. Normally, its resistance is very high and sometimes it so high as 1000000 ohms. But when light falls on it, resistance drops dramatically. Sometimes it is referred as photoconductor or Cds device because Cds is a material which shows variation in resistance with the variation of light. LDR is made by high resistance semiconductor material. When light falls on it with a specific frequency then semiconductor material absorbs photons. These photons energize the bound electrons and they jump from valence band to the conduction band. As a result, free electrons conduct electricity by lowering the resistance.

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CHAPTER 3

PLC

PROGRAMMABLE LOGICAL CONTROLLER

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3.1 History
In 1968 the first criteria for designing a Programmable controllers has been made which was specified by the Hydramatic Division of the General Motors Corporation. Their primary goal was to Get rid of the high costs related with non-flexibility, relay controlled Systems. Their main purpose is to provide the following specifications.        should be low price control system with relay system which are being used Competent and supportive system should be introduced that can manage itself within the industrial environment. Replacement of input and output interface should be simple. Standard form of controller had to be designed, which provides flexibility in a system. The control system should be capable to pass the collected data to a fundamental system. Re-use of the system should be possible. Programming of the controller should be simple so that it can easy to understand by and person.

Control system usually depends on production requirement. If production requirement change control system will also change due to which it becomes very expensive when the change becomes so common. As relays are mechanical devices they also have a very short lifetime which required strict hold to maintenance schedules and also troubleshooting such device was also quite difficult as there are so may relays. As there are multiple that can be controlled using relays so the circuitry is also very complex and confusing. These "new controllers" had to be programmed easily and controlled and also can be easily maintained. The lifetime had to be long and programming changes easily performed. They also had to survive the harsh industrial environment. That's a lot to ask! The answers were to use a programming technique most

3.1.1 The First Programmable Controller
In order to satisfy the specifications of Hydramatic’s, the programmable controller had their first Product in 1969. The functions of that PLC is just like a relay but it is replaced by the hard-wired relay logic system, and it uses electrical devices to switch electrical circuits mechanically. They met all the requirements which are required. These controllers used less space, were easily installed, and can be used more than once. The controller programming, although a little dull. In a very short interval of time programmable controller use started to extend to other industries.

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3.1.2 The Conceptual Design of PLC
The first programmable controllers replaced by relays and their primary function were to perform all those function which can be performed by the help of relays in a fast and efficient way. They were easily installed, used considerably less space and energy, had diagnostic tool that helps to troubleshoot the problem. These operations included ON/OFF control of machines and all those processes which required repetitive operation. The program controllers are relatively a new technology as compare to the other type of controllers. Its features are improving day by day.

3.1.3 Today’s Programmable Controller
Many technological advances in the programmable controller industry Continue today. These advances not only affect programmable controller Design, but also the philosophical approach to control system architecture. Changes include both hardware (physical components) and software (control program) upgrades. The following list describes some recent PLC hardware enhancements:      Due to advanced microprocessor and electronic technology faster scan times are being achieved. Small, low-cost PLCs having more power than their ancestor (see Figure 1-2), which can replace by four to ten relays. More input/output (I/O) systems can be used in less space that can interface at low cost. Special interfaces have allowed certain devices to be connected directly to the controller. Typical interfaces include thermocouples, strain gauges, and fast-response inputs. Peripheral equipment has improved operator interface techniques, and system documentation is now a standard part of the system.

Like hardware advances, software advances, such as the ones listed below, have led to more powerful PLCs:    PLCs have incorporated object-oriented programming tools and multiple languages based on the IEC 1131-3 standard. Small PLCs have been provided with powerful instructions, which extend the area of application for these small controllers. High-level languages, such as BASIC and C, have been implemented in some controllers modules to provide greater programming flexibility when communicating with peripheral devices and manipulating data. Advanced functional block instructions have been implemented for ladder diagram instruction sets to provide enhanced software capability using simple programming commands.
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 

Diagnostics and fault detection have been expanded from simple system diagnostics, which diagnose controller malfunctions, to include machine diagnostics, which diagnose failures or malfunctions of the controlled machine or process. Floating-point math has made it possible to perform complex calculations in control applications that require gauging, balancing, and statistical computation. Data handling and manipulation instructions have been improved and simplified to accommodate complex control and data acquisition applications that involve storage, tracking, and retrieval of large amounts of data.

Programmable controllers are now mature control systems offering many more capabilities than were ever anticipated. They are capable of Communicating with other control systems, providing production reports, scheduling production, and diagnosing their own failures and those of the Machine or process. These enhancements have made programmable controllers important contributors in meeting today’s demands for higher quality and productivity. Despite the fact that programmable controllers have become much more sophisticated, they still retain the simplicity and ease of operation that was intended in their original design.

3.2 Programmable Controllers and the Future
The future of programmable controllers not only used to produce new products but also to integrate PLC with other control and factory management equipment PLCs are being incorporated, through networks, into computer-integrated manufacturing (CIM) systems, combining their power an resources with numerical controls, robots, CAD/CAM systems, personal computers, management information systems, and hierarchical computer-based systems. New advances in PLC technology include features such as better operator interfaces, graphic user interfaces (GUIs), and more human-oriented man/machine interfaces (such as voice modules). They also include the development of interfaces that allow communication with equipment, hardware, and software that supports artificial intelligence, such as fuzzy logic I/O systems. Software advances provide better connections between different types of equipment, using communication standards through widely used networks. Knowledge based and process learning–type instructions may be introduced to enhance the capabilities of a system. The user’s concept of the flexible manufacturing system (FMS) will determine the control philosophy of the future. The future will almost certainly continue to cast programmable controllers as an important player in the factory. Control strategies will be distributed with “intelligence” instead of being centralized. Super PLCs will be used in applications requiring complex calculations, network communication, and supervision of smaller PLCs and machine controllers.

3.3 PLC Applications
Few major industries that use Programmable controllers are as follow:

3.3.1 Chemical/Petrochemical
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     

Finished product handling Materials handling Mixing Off-shore drilling Pipeline control Metal casting

3.3.2 Manufacturing/Machining
         Assembly machines Boring Cranes Grinding Material Conveyor Milling Painting Plating Welding

3.3.3 Power
     Sorting Load shedding Coal handling Winding Wood Working

3.3.4 Mining
    Ore processing Loading/Unloading Water/Waste Management Bulk Material Conveyor

3.3.5 Food/Beverages
    Blending Brewing Container Handling Filling
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  

Load Forming Weighing Warehouse storage

3.4 PLC Product Application Ranges
The figure given below graphically illustrates programmable controller product ranges. This chart is not definitive, but for practical purposes, it is valid. The PLC market can be segmented into five groups:  
 



Micro PLCs Small PLCs Medium PLCs Large PLCs Very Large PLCs

I/O Count

The A, B, and C overlapping areas in above figure reflect enhancements, by adding options, of the standard features of the PLCs within a particular segment.

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3.4.1 Micro PLCs
Micro PLCs are used in those applications which control such devices that required up to 32 inputs and outputs.

3.4.2 Small PLCs
Small PLCs are used where 32 to 128 inputs and outputs are required for controlling certain device.

3.4.3 Medium PLCs
The medium PLC’s has 64 to 1024 Inputs and outputs.

3.4.4 Large PLCs
The large PLC’s has (512 to 4096 I/O), and very large (2048 to 8192 I/O) PLCs complete

3.5 Advantages of PLC
In general, PLC architecture is more flexible and simple as compared to other controllers which allows the user to change it whenever it is required if the requirement of a system has changed in future. They can easily be replaced, having great memory and also have more inputs and outputs as compared to other controllers. They are faster than other controllers and can be re-useable and if any system required more I/O’s that a specific PLC has than those I/O’s can be increased using expansion card or its memory can also be increased. Due to the elimination of hard-wired control system PLC’s causes a great favor to achieve the flexible control systems. When it’s once installed then the control panel can be changed manually or automatically in order to meet the requirements which changes day by day without changing the field wiring as they are not physically connected to field input and output devices as in hard-wired system. There is only one connection which is with the control program that can be changed easily when required. Due to flexibility it is time saving as there is a very fast CPU inside the PLC which allows communication from local or from far field devices and it also saves a lot of cost.

3.5.1 Ease of Installation
As stated earlier the PLC’s are very small in size so they can be mounted and placed very easily and required less space as compare to the relay control panel. This placement can be done very quickly as compared to the relay replacement. For connection purpose, normally coaxial cable or a twisted pair of wires is used, that is connected to the remote station with the CPU. Due to its
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effectiveness and simplicity labor power has also reduced a lot due to which labor cost has also reduced.

Space Efficient Design of PLC

3.5.2 Ease of Maintenance and Troubleshooting
PLC’s were made from the beginning in order to maintain easily and in many cases related to failure are related to input/output devices rather than PLC’s CPU or I/O interface system and in order to troubleshoot such problems Programming devices are used which tells the user why the system is not working properly by checking certain things like I/O’s, programmed instructions and other features of the PLC’s. By noticing out the problem, The system can be recover easily Usually the problem occurs in field devices and there is a very less chance for the problem to occur in I/Os or in CPU which is shown in fig below:

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3.6 PLC Components
The three components of the CPU are:  The processor  The power supply  The memory system The figure illustrates a simplified block diagram of a CPU. The architecture of CPU can be different and that thing is totally depends upon manufacturer but the components remains the same.

CPU Block Diagram In this Figure, the power supply is enclosed inside the CPU; however, the power supply can be separated from the CPU and can be placed next to it CPU can also be called as processor; however, it contains all those necessary elements that make the system intelligent. In general, the processor executes all the instructions that are written in form of ladder logic diagram and then it is stored in the memory system, while the system power supply provides all of the required voltage levels to make sure that proper operation of the processor and memory components are being performed or not.

3.6.1 PROCESSORS

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The main function of Processor is to the principal function of the processor is to rule and run the activities of the entire system. The system program also known as executive is used to perform such functions. It is basically as supervisory program which is permanently stored in processor and has a purpose of control, process and communicates with other devices through programming device communication between PLC and the user is accomplished. It can also be used to communicate with other field devices, I/0 modules, operator interface. More than one processor can also be used in a PLC’s CPU to perform certain operations. The main purpose of doing this is to increase speed of those operations which has to be performed. This process is known as multiprocessing

3.6.1.1 Processor Scan
The main function of a PLC is to read all of the field input Devices, Execution of a program which is totally depend on logic and also update the program and then execute the control program. First of all the internal programmed logic will be executed, which will energized or deenergized the internal output coil and turn them ON or OFF according to the program. However, this energizing and de-energizing of coils will not turn ON or OFF the field devices. First the processor evaluate the control logic program then turn the internal coil ON or OFF then update the output interface module then the field devices will perform certain operation. This process of reading the inputs, executing the program, and updating the outputs is known as the scan.

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Above figure shows a graphic representation of the scan. This operation is usually performed in top to bottom process and scanning will repeated again and again to perform operations. The time taken for the PLC to perform operations and update the outputs is known as scan time. This time is usually depends on some factors like the amount of memory used in a program larger the memory more will be the scan time and also on the type of instruction are used as some instructions required more time to execute as compared to other instructions. Single scan time can be vary from a few tenths of a millisecond to 50 milliseconds. However, there are some other factors which can affect scan time like remotely controlling the I/O’s as it depends upon the distance. Larger the distance more will be the scan time as PLC has to receive and send data remotely. Monitoring control program can also affect scan time as microprocessor sends the status of the coils and contacts.

3.6.2 System Power Supply
It plays a very important role to perform the operations as it provides the voltages to the devices. It usually provides internal DC voltages to the system components like processor, memory, and input/output interfaces). It’s another function is to monitor and regulate the supplied voltages and warn the CPU if something is wrong.

3.6.2.1 The Input Voltage
The input voltage is in the form of AC or DC which is totally depends on PLC requirements. Some requires DC voltage source and others required AC which accept require a 120 VAC or 220 VAC power sources, while a few controllers will accept 24 VDC. It should be kept in mind that the selected Power supply should be able to tolerate a 10 to 15% variation in line voltage conditions as there may be voltage fluctuation occurs at any time.

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3.6.3 Memory Overview
The memory system is inside the PLC’s CPU where all the instructions or program are stored and executed to provide the required control. It is a very important feature of PLC which allows the user to change the program quickly and easily. This feature is provided by the PLC architecture.

3.6.3.1 Memory Section
The total memory system in a PLC is actually composed of two different memories: (see figure given below)  The executive memory  The application memory

Block Diagram of total PLC memory

Executive memory is regarded as to be the part of PLC itself where permanently stored program are placed. Activities like Execution of control program. These supervisory programs direct all System activities, such as execution of the control program and communication with secondary devices etc. This memory is not available for the user. The application memory provides the memory space for the user programmed instruction that provides a storage area for the userprogrammed instructions that structure the application program.

3.6.3.2 Memory Structure and Capacity: Basic structural units
PLC memories are considered to be two-dimensional arrays of single unit storage cells, which stored a single piece of information in the form of 1 or 0.As each cell can store only one binary digit therefore it is called as a bit. A bit is the smallest structural unit of memory. Actually those cell uses Voltage charges which represent in form of 0’s and 1’s if the voltage is applied, it show
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1 and if a voltage is not applied then it shows 0, or we can say that a is ON if the stored information is 1 and if the bit is OFF the stored information is 0. This ON and OFF status is known as bit status Sometimes, a processor must handle more than a single bit of data at a time.

Memory Capacity and Utilization
Memory capacity plays an important role where PLC application is considered. Specifying the right amount of memory is also very important because by doing this one can save the costs of hardware and also the time which is related to the additional memory. Specifying the memory capacity is also important as Some PLC’s are non-expandable. This usually happen in smaller PLC’s having I/O’s less than 64. But these PLC’s are usually used in small PLC’s and their builtin memory is quite enough to perform small operations. Medium and Large PLC’s me mory can be expandable. The term memory utilization describes that how much data can be stored in one location or how many memory locations are required to store each type of instruction. Normally this type of information is provided by the manufacturer.

3.7 Programming Device
This device is used to modify and for troubleshooting if any problem occurs. Most PLCs are programmed using very similar instructions. It is not usually required to connect the programming device with the PLC. Program can be update or troubleshoot without any connection with the PLC. Once the program is being updated then this device can be disconnected. The two basic types of programming devices are:  Mini-Programmers  Personal Computers

3.7.1 Mini-Programmers
Mini-programmers, are the handheld or manual programmers, which are cheap and a convenient way to program small PLCs (up to 128 I/O).Physically, these devices are similar to calculator but their display is quite big. The display screen is usually of LED or dot matrix. Some controllers have also built-in mini-programmers. In some instances, these built-in programmers can be removed from the PLC. They are mainly used for editing and monitoring. These programmers are designed in such a way that they can easily be used with more than one controller or they are more-friendly with other.

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3.7.2 Personal Computers
Personal computers are usually used in place of programming devices due to which mostly manufacturers provides necessary PC based soft ware’s which are normally used for documentation, editing and real-time monitoring of the PLC’s, allows the programmer to define the purpose and function of each I/O address that is used in a PLC program. Ladder rungs or control program can be shown on the pc screen. The choice of choosing Personal computers is not very suitable because of PLC programming capabilities but because PCs are usually present where the programming has been performed. Such system provides a lot of flexibility which makes them very easy to use

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PC connected to PLC

3.8 The Role of PLC
PLC is commonly called as heart of control system in automated controls. It has a application memory which is inside the PLC CPU which is used for the execution of the program. PLC monitors the field devices all the time which depends on the logics made in PLC programming software though which output is being controlled. The input and output devices which are being controlled by the PLC are as follow:

3.8.1 Input Devices
Automated system depends upon the ability of the PLC to read and sense the signal from input filed devices. Example of manual input field devices are keypad, pushbutton, switches etc Other input devices which are usually used for detection or sensing the signal are proximity switch, Photoelectric sensors, limit switch etc.

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3.8.2 Output Devices
Those Devices which are used to perform operations are called as Output devices. They get the signal from the input devices which are connected to the PLC. Here PLC plays the role of bridge between the input and output device. When the Output Device gets the signal from the PLC it perform certain operation depend on the input condition. Some Common devices are relays, buzzer, solenoid etc. Other output devices which are used for informing are alarm, pilot lamp etc

3.9 Introduction to ladder programming language: 3.9.1 Ladder Diagram and the PLC
The ladder diagram usually works on conditional statements i.e the operation which are depend on the certain conditions as an input switch is on it has to perform certain operations according to those conditions implemented by the user. Instructions that are executed should be execute in a sequence. This can be done in the form of a circuit diagram and not in coding like c or assembly.
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Coding can be done inside a logic diagram and these logics are related to field devices attached to any system. Representing ladder logic in the form of circuit diagram will help user to understand easily and also be acceptable in different industries. This type of Circuit diagram is known as Ladder Diagram which is obvious for the engineer or programmer. It plays a very important role for implementing any control system. Figure given below illustrates a relay ladder logic circuit and the PLC ladder language representation of the same circuit. The original ladder language has evolved the ladder programming into a more powerful instruction set. New functions have been added to the basic relay, timing, and counting operations. that is, handle and transfer data within the programmable controller. These instructions are followed by the simple principles of basic relay logic, although they allow complex operations to be implemented and performed. Set of instruction has also been added to the basic ladder logic also include function blocks which operates on a block of data.

.

3.9.2 Ladder Diagram Format
The ladder diagram language is represented by set of instruction that is used to create PLC programs. The ladder instruction symbols can be formatted to obtain the desired control logic, which is then entered into memory. These instructions set which are in the form of symbols also called as contact symbology.

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The input condition is responsible to control the output and to perform functional operations which are in the ladder diagram program. Ladder diagrams achieving this control by using rungs, figure shows the basic structure of a ladder rung. In general, a rung consists of a set of input conditions which is at the start of every rung and an output instruction at the end of the rung (represented by a coil symbol). The contact instructions for a rung may be referred to as input conditions, rung conditions, or the control logic. A ladder rung is TRUE when it has logic stability. Logic stability exists when power flows through the rung from left to right. The execution of an event occurs when continuity is provided to the output. Continuity depends on the path, if it is closed then continuity occurs which allows the power to flow from left to right. In a single rung more than one output coils can exists, which represents the status of the function being performed, will activate the block to perform the instruction. Thus, this instruction says: if the input is ON because the desired logic has continuity, then execute the block instruction.

3.9.3 Ladder Relay Instructions
Ladder relay instructions are the most basic instructions in the ladder diagram instruction set. These instructions represent the ON/OFF status of connected inputs and outputs. Ladder relay instructions use two types of symbols are used by ladder relay instruction: contacts and coils. Contacts represent the input conditions that control the output in a given rung. Coils represent the output in a rung represent a rung’s outputs.

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Table lists common ladder relay instructions. In a program, each contact and coil has a given address number, which identifies what is being estimate and what is being controlled. The address number represents the I/O table location of the input/output which are used in the program. A contact can be used throughout the control program in order to evaluate the condition. The format of the rung contacts used in a PLC program depends on the preferred control logic. The placement of contacts is usually depends on the output which has to be controlled. It can be placed in series, parallel or series/ parallel configuration. After the placement is finished that depends upon the logics then the continuity is checked from left to right. If continuity exist, then the rung condition is true if it doesn’t then it is false.

3.10 Timers and Counters
PLC programming software also contains timers and counters which are the internal instructions that provide the same functions as hardware timers and counters. They make the device active or make it stop after a certain time interval or a count has occurred a preset value. They are considered to be the part of internal outputs and a fundamental part of ladder diagram instruction set. To time an event time bases (TB) are used in Timer instructions. Time base may have one or more time bases (TB). For instance, if a user wants to give a delay of 20 seconds, then the counting of time base must be know in order to give the delay of 20 seconds. For example if the
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timer base is of 1 second then it should be count 20 times to give the delay of 20 seconds to perform specific output operation. Sometimes a delay of .01 sec or more is required as the ON time of PLC is more as compared to the other components. This delay is given to perform a roper operation. Counter instructions are used to count number of events, an example can be of conveyor belt where different types of products can be passed like boxes, bottles and other components and counter will count those components etc. Counters and timers have two values that are a preset value and an accumulated value. The preset value is the required number of ticks that has to be performed before the output turns ON. The accumulated value shows the current value or the number of ticks that have gone during the timer or counter operation. The preset and the accumulated values are stored in their specified register which preset register and accumulated register. The value of both these registers is defined while writing a program.

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CHAPTER 4

PROJECT RELATED TRILOGY PLC

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4.1 Introduction
The reason of using this PLC is because it is very cheap as compare to other PLC’s and in the situation of Pakistan these days people can’t afford to buy other expensive PLC’s like Allen Bradley and Siemens.

Model: PLC model which we are using is of M-series. I/O ports: It has 24 I/O ports. Software: The software for using this PLC is trilogy and we are using trilogy version 6.31. The
following ladder logic functions are used in this software: The list of functions which are in this programming language are as follow:

The symbols and their function are shown in the above figure

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In ladder logic programming, first we have to initialize the number of I/O’s used according to the program as shown in figure below: The symbol which discussed earlier can be seen in the figure by clicking on circuit and then click on “Insert Circuit” The I/O table is the table where we initialize our function names which have to be used in the program along with their address. Address in necessary to describe as without it program will unable to run properly. The function names which we described in the I/O table must be used while making ladder logic or else the software won’t recognize it. The I/O table can be seen in the figure below:

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Function name can also be made while writing a ladder logic program in the software by double clicking on the input switch or output coil for example;

There are also some custom functions which we can program according to our requirements.The window used for custom functions is shown in the figure below.

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This screen can be appeared by clicking on the open cusfn button which is on the middle top of the programming screen. This function is usually used to write the programs in C and assembly language which is store inside the custom function and when this function is called inside the ladder logic program then it perform certain operation depends upon the code that has been written in this function.

4.2 Simulator
This software has a built in simulator which is used to diagnose the ladder logic programming. Once the programming is finished we can check it if the program is working fine or not. From the figure shown below it can be seen that the simulator has separate table for each function like input, timer counter relay and output. In this figure you can see the function names which are made according to the function requirement in the function table. Now the address of these functions can be seen from the left side of these function by clicking on these addresses function will start performing.

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4.3 PLC Based Project Work 4.3.1 Motion sensor

This is the ladder diagram of controlling Motion sensor through trilogy. Here we are controlling it in such a way that if motion sensor, sense any motion it will turn on the lights and after sensing it, if it doesn’t detect any motion it will turn off the lights after 5 minutes. We have generated the delay of 5 minutes by using timer in it. Motion sensor will work only if input switch “m_enabled” is ON otherwise only mechanical system will work. Here “m_enabled” is an internal relay. We can ON or OFF this switch by using scada software which is connected to PLC We are also using motion sensor for security purpose which we have discussed in GSM topic.

4.3.2 Door switch
The purpose of using door switch is also for security purpose. We are using door switch as a counter. In office timing i-e from 7 am to 7 pm, the door switch is usually closed or disabled whether if the door is closed or open, but when the office time is over and if the door is open or closed then it will not only count that how many times..

Ladder Diagram Of Door Switch

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The table given below shows the initialization of numbers in which date and time can be saved during the opening or closing of door on the given times. .

Data Logging table

4.3.3 LDR
We are using LDR for outside lightening system. If the intensity of sunlight is low with the specific level then it will turn ON the lights. If the intensity of sunlight is high with certain level it will turn off the lights and that process will goes on. The simple ladder diagram logic of LDR is shown below:

Ladder Diagram of LDR

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4.4 Communication Module
The connection of PLC’s Ethernet with the network system is provided by the communication module. PLCs have incorporated with communications ports, usually 9-pin RS-232 is used for this purpose, but optionally EIA-485 or Ethernet can also be used depends upon the communication which has to be established. Modbus, BACnet or DF1 is usually included as one of the communications protocols. Through this communication module, one can communicate PLC with other system over a network like computer running software like SCADA or web browser. For larger PLCs peer-to-peer communication system usually occurs between the processors. By doing this complex system has been controlled separately through which coordination over a communication link exist for the sub-system. HMI devices such as keypads can also be linked by using this communication.

Ethernet/modem:

communication with remote computers is occurred by this communication.

ASCII modem: It is used for Serial communication with RS-232 or 485 4.4.1 Remote Terminal Units
    An RTU converts the Analog signals from the equipment to its digital value. Their purpose is to collect digital information and they are installed in the field in the form of small computerized units. RTU’s are used to collect information and gather reports from sensors and sends the command to the relays Gathering of data from field devices like pump, valves, alarm etc can’t be achieved until The MTU starts a send command.

4.4.2 Master Terminal Units
RTU uses and gather the data, but MTU is used to display that data and also overwrite the setting change the data and displayed to a human with the help of an interface when necessary. MTU is often a computing platform like a PC, which runs SCADA Software.    Operators use this to monitor and control a large number of RTUs. Master units provide a human interface to the system and automatically regulate the managed system in response to sensory inputs. A SCADA network consists of one more MTU depending upon the need and requirements.

4.4.3 Modbus
In 1979 Modicon published this serial communications protocol to use it with programmable logic controllers (PLCs). It becomes very famous these days and it is very simple to use, and now it is easily available in the market. It is being used a lot in the industrial environment. The reasons are as follow:
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  

It has been developed with industrial applications in mind It is openly published and royalty-free It is easy to position and preserve

By using Modbus, communication between approximately 240 devices connected to the same network can be possible, for example we can measures temperature and humidity and corresponds the results to a computer. To connect supervisory control and data acquisition (SCADA) systems with RTU, Modbus is also used. Each device which have to communicate using Modbus should have a unique address. A Modbus command contains the Modbus address of the device it is planned for. Only the planned device will act on the command, even though other devices might receive it. All Modbus commands also checks the information to make sure that that a command arrives undamaged There are many modems and gateways that support Modbus, as it is a very simple protocol and often copied. Some of them were specifically designed for this protocol.

4.4.4 RS-232
Rs-232 is used for serial communication. USB is faster as compared to RS-232, It is designed to make easier for device drivers to communicate with hardware. USB includes a protocol for transferring data to devices which makes it complex than the RS-232, also USB can’t be used for more than 5 meters of cable, so for longer distances, RS-232 is normally used. The data communication links used with peripheral equipment can be unidirectional or bidirectional. If a peripheral is strictly either an input or an output device, then data transmission occurs in only one direction. In this case, a unidirectional serial signal line is all that is required to complete the link. Devices that serve as both input and output devices (e.g., video terminals) require bidirectional links. There are two ways to achieve this bidirectional communication. First, a single data line can be used as a shared communication line. The data can be sent in either direction, but only in one bidirectional communication is required; two lines can connect the PLC to the peripheral. One line would be assigned permanently as an input, while the other would be a permanent output. This mode is known as full duplex.

(a) Unidirectional
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(b) Half-duplex

(c) Full duplex

RS-232 Data line Description

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The EIA RS-232 is a proclaimed standard that defines the interfacing between data equipment and communication equipment that employs serial binary data interchange. This standard defines both the electrical signals and the mechanical details of the interface. A complete RS- 232C interface consists of 25 data lines, which encompass all of the possible signals for simple and complex communication interfaces. Although several of these lines are specialized and a few are undefined, most peripherals require only three to five lines to operate properly. Table 8-3 describes the 25 data lines as specified by the EIA. Figure 8-44a illustrates an RS-232C data communication system using a telephone modem, while Figure 8-44b shows the RS-232 wiring connections from a computer to a smart EIA PLC interface module.

RS-232 wiring connections from a PLC with Computer The RS-232 standard calls for certain electrical characteristics. Some of these specifications are as follow:  The signal voltages at the interface point should be a minimum of +5 V and a maximum of +15 V for logic 0; for logic 1, the minimum is –15 V and the maximum is –5 V.  The maximum recommended cable distance is 50 feet, or 15 meters; however, longer distances are permissible provided that the resulting load capacitance, measured at the interface point and including the signal terminator, does not exceed 2500 picofarads. The drivers used must be able to withstand open or short circuits between pins in the interface.  The load impedance at the terminator side must be between 3000 and 7000 ohms, with no more than 2500 picofarads capacitance.  Voltages under –3 V (logic 1) are called mark potentials (signal conditions); voltages above +3 V (logic 0) are called space voltages.

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CHAPTER 5 GSM (Global System for Mobile Communications)

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5.1 GSM History
Analog cellular telephone systems were experiencing rapid growth in Europe, particularly in Scandinavia and the United Kingdom during the early 1980s, but also in France and Germany. Each country developed its own system, but the problem is it is un-suitable for others system which was not required at all. The reason is that the mobile equipment limited to operation within national boundaries and also a little market is available with such type of equipments which in a unified Europe were increasingly unimportant, but there was also a very limited market for each type of equipment, so economies of scale and the successive savings could not be appreciate. The Europeans realized this early on, and in 1982 a special group is formed called the Groupe Special Mobile (GSM) to study and develop a pan-European public land mobile system. The proposed system had to meet certain criteria:  Good subjective speech quality  Low terminal and service cost  Support for international roaming  Ability to support handheld terminals  Support for range of new services and facilities  Spectral efficiency  ISDN compatibility In 1989, GSM responsibility was transferred to the European Telecommunication Standards Institute (ETSI), and phase I of the GSM specifications were published in 1990. in mid-1991, Commercial service was started, and there were 36 GSM networks in 22 countries in 1993 . Although standardized in Europe, GSM is not only a European standard. Over 200 GSM networks (including DCS1800 and PCS1900) are operational in 110 countries around the world. In the beginning of 1994, there were 1.3 million subscribers worldwide, which had grown to more than 55 million by October 1997.

5.2 Mobile Station
The mobile station (MS) has mobile equipment (the terminal) and a smart card called the Subscriber Identity Module (SIM). User has a personal mobility by using SIM which does not depend on a specific terminal. By inserting SIM card into another GSM terminal, then calls can be received by the user at that terminal, make calls from that terminal, and other subscribed services can be received. The mobile equipment is uniquely identified by the International Mobile Equipment Identity (IMEI). In order to identify the subscriber to the system the SIM card contains the International Mobile Subscriber Identity (IMSI) which provides a secret key for authentication, and other information. The IMEI and the IMSI are independent, thereby allowing personal mobility. A

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password or personal identity number can be provided from the SIM card for the protection against unauthorized use.

5.3 Base Station Subsystem
The Base Transceiver Station (BTS) and the Base Station Controller (BSC) came under the category of Base station subsystem. Standardized ABIS interface is used for communication purpose.

5.3.1 ABIS interface
The Base Transceiver Station handles the radio-link and also defines a cell protocols with the Mobile Station. A large number of BTSs deployed in large urban areas, thus the requirements for a BTS are roughness, consistency, portability, and minimum cost.

The BTS or Base Transceiver Station is also called an RBS or Remote Base station. Traffic gets sent their first as the base station is under direction of a base station controller. Calls can be gathering from many base stations and passes them on to a mobile telephone switch. From that switch calls can be received and transmit from the regular telephone network.

5.4 The Base Station Controller
The Base Station Controller manages the radio resources for one or more BTS’s. Radio -channel setup, frequency hopping, and handovers can be handled by the Base Station Controller. The BSC is used to connect the mobile station and the Mobile service Switching Center (MSC).

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5.5 Architecture of The GSM Network
Functional entity of GSM network, whose functions and interfaces are specified. Figure 1 shows the layout of a generic GSM network. The GSM network can be divided into three broad parts. The Mobile Station is approved by the subscriber. Radio link is controlled by the Base Station. Mobile services Switching Center (MSC) is the main part of the Network Subsystem, which performs the switching of calls between the mobile users, and between mobile and fixed network users. Mobility supervision operations are also handled by the MSC. Air interface or radio link is used to communicate the Mobile Station and the Base Station Subsystem. The Base Station Subsystem communicates with the Mobile services Switching Center across the A interface.

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5.6 SMS through Hyper Terminal 5.6.1 SMS
SMS stands for short message service which is used to send and receive text messages to and from mobile telephones. Alphanumeric combination words or number are includes in this text. In December 1992 first short message has been sent from a personal computer mobile phone to a Vodafone GSM network in the UK. Each short message is usually comprises of 160 characters in length.

5.6.2 Hyper Terminal
HyperTerminal is a terminal emulation program that comes with every version of the Windows operating systems like Windows 95, Windows 98, Windows NT and Windows 2000. This software was developed by the Hilgraeve for communication purpose. It can also be used to transfer data between two computers using the serial ports and for the serial port control of the external devices, robots, scientific instruments and radio communication stations. Troubleshooting can also be done by using HyperTerminal when connected with the modem. Commands can be send to your when it is working properly or not. With Hyper terminal the user can have the ability of connecting and transferring files between the two computers.

5.7 Introduction to AT Commands
AT commands are instructions used to control a modem. AT is the abbreviation of Attention. Every command line starts with "AT" or "at". That's why modem commands are called AT commands. Many of the commands that are used to control wired dial-up modems, such as ATD (Dial), ATA (Answer), ATH (Hook control) and ATO (Return to online data state), are also supported by GSM/GPRS modems and mobile phones. Besides this common AT command set, GSM/GPRS modems and mobile phones support an AT command set that is specific to the GSM technology, which includes SMS-related commands like AT+CMGS (Send SMS message), AT+CMSS (Send SMS message from storage), AT+CMGL (List SMS messages) and AT+CMGR (Read SMS messages). Note that the starting "AT" is the prefix that informs the modem about the start of a command line. It is not part of the AT command name. For example, D is the actual AT command name in ATD and +CMGS is the actual AT command name in AT+CMGS. However, some books and web sites use them interchangeably as the name of an AT command. Here are some of the tasks that can be done using AT commands with a GSM/GPRS modem or mobile phone:

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Information of Mobile or GSM
Get basic information about the mobile phone or GSM/GPRS modem. For example, name of manufacturer (AT+CGMI), model number (AT+CGMM), IMEI number (International Mobile Equipment Identity) (AT+CGSN) and software version (AT+CGMR).

Information of the Subscriber
Get basic information about the subscriber. For example, MSISDN (AT+CNUM) and IMSI number (International Mobile Subscriber Identity) (AT+CIMI).

Status of Mobile Phone or GSM
Get the current status of the mobile phone or GSM/GPRS modem. For example, mobile phone activity status (AT+CPAS), mobile n+etwork registration status (AT+CREG), radio signal strength (AT+CSQ), battery charge level and battery charging status (AT+CBC).

Connection
Establish a data connection or voice connection to a remote modem (ATD, ATA, etc).

Lock Facility
Perform security-related tasks, such as opening or closing facility locks (AT+CLCK), checking whether a facility is locked (AT+CLCK) and changing passwords (AT+CPWD). (Facility lock examples: SIM lock [a password must be given to the SIM card every time the mobile phone is switched on] and PH-SIM lock [a certain SIM card is associated with the mobile phone. To use other SIM cards with the mobile phone, a password must be entered.])

Changing the Configuration
Get or change the configurations of the mobile phone or GSM/GPRS modem. For example, change the GSM network (AT+COPS), bearer service type (AT+CBST), radio link protocol parameters (AT+CRLP), SMS center address (AT+CSCA) and storage of SMS messages (AT+CPMS).

Save and Restore Configuration
Save and restore configurations of the mobile phone or GSM/GPRS modem. For example, save (AT+CSAS) and restore (AT+CRES) settings related to SMS messaging such as the SMS center address.

SMS Read
In order to read any message, syntax will be AT+CMGR=1
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It will read the first message

SMS Deletion
In order to delete any message from memory, Its syntax will be: AT+CMGD=1 It will delete the first message

SMS Write
In order to write a SMS to any number, syntax will be AT+CMGW=”03002453603”; This command firstly send the request to a given destination and the number send back a sign like “>” and then we write a message and sent it to the given number shown above

AT Command Operations
There are four types of AT command operations:

Test operation
A test operation is used to check whether a certain AT command is supported by the GSM/GPRS modem or mobile phone.

Set operation
A set operation is used to change the settings used by the GSM/GPRS modem or mobile phone for certain tasks.

Read operation
A read operation is used to retrieve the current settings used by the GSM/GPRS modem or mobile phone for certain tasks.

Execution operation
An execution operation is used to perform an action or retrieve information/status about the GSM/GPRS modem or mobile phone.

Extended Commands
Extended commands are as follow:

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AT commands that start with "+". All GSM AT commands are extended commands. For example, +CMGS (Send SMS message), +CMSS (Send SMS message from storage), +CMGL (List SMS messages) and +CMGR (Read SMS messages) are extended commands.

5.8 General Syntax of Extended AT Commands
The general syntax of extended AT commands is straightforward. The syntax rules are provided below. The syntax of basic AT commands is slightly different. We will not cover the syntax of basic AT commands in this SMS tutorial since all SMS messaging commands are extended AT commands.

Syntax rule 1
All command lines must start with "AT" and end with a carriage return character. (We will use <CR> to represent a carriage return character in this SMS tutorial.) In a terminal program like HyperTerminal of Microsoft Windows, you can press the Enter key on the keyboard to output a carriage return character.

Example
To list all unread inbound SMS messages stored in the message storage area, type "AT", then the extended AT command "+CMGL", and finally a carriage return character, like this: AT+CMGL<CR>

Syntax rule 2
A command line can contain more than one AT command. Only the first AT command should be prefixed with "AT". AT commands in the same command-line string should be separated with semicolons.

Example
To list all unread inbound SMS messages stored in the message storage area and obtain the manufacturer name of the mobile device, type "AT", then the extended AT command "+CMGL", followed by a semicolon and the next extended AT command "+CGMI": AT+CMGL;+CGMI<CR> An error will occur if both AT commands are prefixed with "AT", like this: AT+CMGL;AT+CGMI<CR>

Syntax rule 3
A string is enclosed between double quotes.

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Example
To read all SMS messages from message storage in SMS text mode (at this time you do not need to know what SMS text mode is. More information will be provided later in this SMS tutorial), you need to assign the string "ALL" to the extended AT command +CMGL, like this: AT+CMGL="ALL"<CR>

Syntax rule 4
Information responses and result codes (including both final result codes and unsolicited result codes) always start and end with a carriage return character and a linefeed character.

Example:
After sending the command line "AT+CGMI<CR>" to the mobile device, the mobile device should return a response similar to this: <CR><LF>Nokia<CR><LF> <CR><LF>OK<CR><LF> The first line is the information response of the AT command +CGMI and the second line is the final result code. <CR> and <LF> represent a carriage return character and a linefeed character respectively. The final result code "OK" marks the end of the response. It indicates no more data will be sent from the mobile device to the computer / PC. When a terminal program such as HyperTerminal of Microsoft Windows sees a carriage return character, it moves the cursor to the beginning of the current line. When it sees a linefeed character, it moves the cursor to the same position on the next line. Hence, the command line "AT+CGMI<CR>" that you entered and the corresponding response will be displayed like this in a terminal program such as HyperTerminal of Microsoft Windows: AT+CGMI Nokia OK

Case Sensitivity of AT Commands
In the SMS specification, all AT commands are in uppercase letters. However, many GSM/GPRS modems and mobile phones allow you to type AT commands in either uppercase or lowercase letters. For example, on Nokia 6021, AT commands are case-insensitive and the following two command lines are equivalent: AT+CMGL<CR> at+cmgl<CR>
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Mode Testing
There are two types of mode text mode and PDU mode. To select one of the mode, its syntax will be as follow: AT+CMGF=1 This command shows that the mobile set is in text mode IF AT+CMGF=0 Then it is in PDU mode

5.9 AT Commands for SMS Text Mode
Some AT Commands are as follow:

AT+CSMS: Select Message Service AT+CPMS: Preferred message storage AT+CMGF: Message Format AT+CSMP: Set Text Mode Parameter AT+CSCA: Service center Address AT+CSDH: Show Text Mode Parameter AT+CSCB: Select Cell Broadcast Message Types AT+CSAS: save settings AT+CRES: Restore Settings AT+CMGL: List Message AT+CMGR: Read Message AT+CMGS: Send Message AT+CMSS: Send Message from Storage AT+CMGW: Write Message to Memory

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5.10 GSM Project Work
1) We use GSM for security purpose. We use internal relay for enabling GSM module. Its purpose is that whenever motion sensor sense any motion then GSM module send a message “Intruder Alert” to the user and also tells that motion is sensed from which room.

GSM Ladder Diagram

2) We also using GSM module for tuning the AC ON or OFF. First we save the message in PLC memory for turning ON or OFF the AC then whenever user send a message to GSM module, it will compare the text which is send b the user with the text which is stored in PLC memory. If the text matched then the AC will ON or OFF according to the user requirement.

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Controlling AC Ladder Diagram

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CHAPTER 6 CODE LISTING

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Initialization
for i=1 to 500 dm[i]=9999 next

Door Opening
for n=1 to 16 if time[1]>=20 & time[2]>=0 | time[1]<=7 & time[2]>=0 then

if ctrpv[1]=1 then dm[1]=time[1]*100+time[2] dm[2]=date[3]*100+date[2]

endif

if ctrpv[1]=2 then dm[3]=time[1]*100+time[2] dm[4]=date[3]*100+date[2]

endif

if ctrpv[1]=3 then dm[5]=time[1]*100+time[2] dm[6]=date[3]*100+date[2] endif

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if ctrpv[1]=4 then dm[7]=time[1]*100+time[2] dm[8]=date[3]*100+date[2] endif

if ctrpv[1]=5 then dm[9]=time[1]*100+time[2] dm[10]=date[3]*100+date[2] endif

if ctrpv[1]=6 then dm[11]=time[1]*100+time[2] dm[12]=date[3]*100+date[2] endif

if ctrpv[1]=7 then dm[13]=time[1]*100+time[2] dm[14]=date[3]*100+date[2] endif

if ctrpv[1]=8 then dm[15]=time[1]*100+time[2] dm[16]=date[3]*100+date[2] endif endif
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next

Door Closing
for o=17 to 32 if time[1]>=20 & time[2]>=0 | time[1]<=7 & time[2]>=0 then

if ctrpv[1]=1 then dm[17]=time[1]*100+time[2] dm[18]=date[3]*100+date[2] endif

if ctrpv[1]=2 then dm[19]=time[1]*100+time[2] dm[20]=date[3]*100+date[2] endif

if ctrpv[1]=3 then dm[21]=time[1]*100+time[2] dm[22]=date[3]*100+date[2] endif

if ctrpv[1]=4 then dm[23]=time[1]*100+time[2] dm[24]=date[3]*100+date[2] endif

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if ctrpv[1]=5 then dm[25]=time[1]*100+time[2] dm[26]=date[3]*100+date[2] endif

if ctrpv[1]=6 then dm[27]=time[1]*100+time[2] dm[28]=date[3]*100+date[2] endif

if ctrpv[1]=7 then dm[29]=time[1]*100+time[2] dm[30]=date[3]*100+date[2] endif if ctrpv[1]=8 then dm[31]=time[1]*100+time[2] dm[32]=date[3]*100+date[2] endif endif next

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BIBLIOGRAPHY Websites
http://www.3gcontrols.co.uk/what-is-bms http://www.reuk.co.uk/PIR-Sensors.htm http://www.technologystudent.com/elec1/ldr1.htm http://www.building-automation-consultants.com/building-automation-history.html http://www.moeller.net/en/products_solutions/solutions/safety/products/safety_door-switches.jsp http://bizsecurity.about.com/od/physicalsecurity/a/security_system.htm http://en.wikipedia.org/wiki/Building_management_system
http://www.privateline.com/mt_gsmhistory/ http://www.wifinotes.com/mobile-communication-technologies/gsm-architechture.html

Books
Shengwei Wang, “Intelligent Buildings and Building Automation”, published by Spon Press, 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN, 2010. L.A Bryan and E.A Bryan, “Programmable Controllers”, Published by Industrial Text Company, Industrial Text and Video Company 1950 Spectrum Circle Tower A-First Floor Marietta, Georgia 30067 (770) 240-2200 (800) PLC-TEXT, 1988, 1997. Hugh Jack, “Automatic Manufacturing Systems With PLCs”, Version 5.0, May 4, 2007, 19932007.

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