SCHOOL BELL & MOTION DETECTED ALARM SYSTEMS FOR HIGH SCHOOLS USING PROGRAMMABLE LOGIC CONTROLLER (PLC) by Muhammet Burak Önen
Sarajevo.2013 1
Abstract Many years ago most schoolhouses had a large large bell that was rung to announce announce the start and end of a school day. day. However, large bells fell out of favor long ago and were replaced by buzzers, digitized recordings or other elect ronic/computerized means of letting students know when classes were starting or changing. As new technology superseded the beautifully crafted bells, many schools were left wondering what to do with their old bells. This project has two parts which are hardware and software.Also this project supports two different systems which are school bell and alarm system with motion detecting. Schneiderr The push buttons, indicator lamp and speakers are connected to Zeli o PLC Schneide SR2 B121 BD (24 V D C) . The PLC controls every signal which is coming from the inputs (push buttons, motion detector) to software and display to the outputs (Indicator lamp and speaker). Using software, Function Block Diagrams (FBD) (FBD) are programmed to control the intervals of time and alarm system in school.
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Tabl e of Con tents Abstract.......................................................................................................2 Goal.............................................................................................................4 Scope...........................................................................................................4 Introduction to PLC.....................................................................................4 PLC Configuration......................................................................................5 Inputs and Outputs.......................................................................................6 Advantages of PLC....................................................................................8 Hardware.....................................................................................................8 Schneider Electric SR2B121BD Zelio Compact PLC Module...................9 Technical Data...........................................................................................10 Wiring System...........................................................................................11 Software.....................................................................................................12 How to Choose PLC..................................................................................12 Function Block Diagram PLC...................................................................14 FBD Application.......................................................................................15 Conclusion.................................................................................................15 Appendix A...............................................................................................16 Appendix B................................................................................................18 References.................................................................................................25
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Goal The purpose to build this project is its fully automatically controlling the daily bell in each school periods and motion detected alarm system usi ng same device. So no need manually ring the bell in each period by the user or no need a computer program to operate the Bell.Beside alarm systems requires many costs and it is hard to provide and control.My purpose to control school bell and alarm system by using same device and decrease the cost.
Scope
Construct a model of bell and alarm system combination.
Program a function block diagram (FBD) to control school bell and alarm system.
Combine all model with software and hardware in order to simulate s chool bell and motion detected alarm system. Build safe using alarm system and control intervals of time with same device.
Background Introduction to PLC Programmable logic controllers are now the most widely used industrial process control technology. A programmable logic controller (PLC) is an industrial grade computer that is capable of being programmed to perform control functions. The programmable controller has eliminated much of the hardwiring associated with conventional relay control circuits. Other benei ts include easy programming and installation, high control speed, network compatibility, troubleshooting and testing convenience, and high reliability.
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PLC Configuration PLCs consist of input modules or points, a Central Processing Unit ( CPU), and output modules or points. An input accepts a variety of digital or analog signals from various field devices (sensors) and converts them into a logic signal that can be used by the CPU. The CPU makes decisions and executes control instructions based on program instructions in memory. Output modules convert control instructions from the CPU into a digital or analog signal t hat can be used to control various field devices (actuators). A programming device is used to input the desired instructions. These instructions determine what the PLC will do for a specific input. An operator interface device allows process information to be displayed and new control parameters to be entered.
Central Process Unit
The Central Process Unit (CPU) is a microprocessor that coordinates the activities of PLC system.It executes the program, process I/O signals and communicates with external devices. Power Supply
This can be built into the PLC or be an external unit. Common voltage levels required by the PLC (with and without the power supply) are 24Vdc, 120Vac, 220Vac. I/O (Input/Output)
A number of input/output terminals must be provided so that the PLC can monitor the process and initiate actions.Indicator lights.These indicate the status of the PLC including power on, program running, and a fault. These are essential when diagnosing problems. 5
Memory
There are various type of memory unit.It is are tha t hold the operating system and user memory.The operating system is actually a system software that coordinates the PLC.Ladder program, Timer and Counter Values are store d in the user memory.Depending on user’s need, various type of memory are available for choise: a) Read-Only Memory (ROM)
ROM is a non-volatile memory that can be programmed only once.It is therefore unsuitable.It is least popular as compared with others memory type. b) Random Access Memory (RAM)
RAM is commonly used memory type for storing the user program and data.The data in the volatile RAM would normally be lost if the power source is removed.However, this problem is solved by backing up the RAM with a battery. c) Erasable Programmable Read Only Memory (EPROM)
EPROM holds data permanently just like ROM.It does not require battery backup.However, its content can be erased by exposing it to ultraviolet light.A prom writer is required to reprogram the memory. d) Electrically Erasable Programmable Read Only Memory (EEPROM)
EEPROM combines the access flexibility of RAM and the non-volatility of EPROM in one.Its contents can be erased and reprogrammed electric ally, however, to a limit number of times.
Inputs and Outputs Inputs to, and outputs from, a PLC are necessary to monitor and control a process.Both inputs and outputs can be categorized into two basic types: logical or continuous.Consider the example of a light bulb. If it can only be turned on or off, it is logical control.If the light can be dimmed to different levels, it is continuous. Continuous values seem more intuitive, but logical values are preferred because they allow more certainty, and simplify control. As a result most controls applications (and PLCs) use logical inputs and outputs for most applications. Hence, we will discuss logical I/O and leave continuous I/O for later. Outputs to actuators allow a PLC to cause something to happen in a process. A short list of popular actuators is given below in order of relative popularity.
Solenoid Valves - logical outputs that can switch a hydraulic or pneumatic flow.
Lights - logical outputs that can often be powered directly from PLC output boards.
Motor Starters - motors often draw a large amount of current when started, so they require motor starters, which are basically large relays. 6
Servo Motors - a continuous output from the PLC can command a variable speed or position.
Inputs come from sensors that translate physical phenomena into electrical signals.Typical examples of sensors are listed below in relative order of popularity.
Proximity Switches - use inductance, capacitance or li ght to detect an object logically. Switches - mechanical mechanisms will open or close electrical contacts for a logical signal. Potentiometer - measures angular positions continuously, using resistance. LVDT (linear variable differential transformer) - measures linear displacement continuously using magnetic coupling.
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Advantages of PLC PLCs have been gaining popularity on the factory floor and will probably remain predominant for some time to come. Most of this is because of the advantages they offer.
• Cost effective for controlling complex systems. • Flexible and can be reapplied to control other systems quickly and easi ly. • Computational abilities allow more sophisticated control. • Trouble shooting aids make programming easier and reduce downtime. • Reliable components make these likely to operate for years before failure.
Hardware The hardware part of this project is Programmable logic controller (PLC) and motion detected alarm model. SCHNEIDER ZELIO SR2B121BD is the type of PLC used in this project as the processor to control the school bell, intervals of the time and holidays. This type of PLC is chosen because it has 4 outputs which is enough for this project and it is suitable for less cost. But if we need to increase amount of the indicator light, we have t o choose another PLC. The motion detected alarm model is constructed to outdoor how this motion detector sensor will detect a person and light the indicator light.When the person who passed front of the sensor, The alert is given for 1 minute by an audio signal alternating 2 s ON, 1 s OFF, and by an indicator light activated by a motion detector. For the modeling alarm model, we can put indicator light wherever we want to see warning but i put it outdoors and for the audible signal, it is better to put the center of school.When we want to reset the system, we should press I3 button which is reset button.If we want, we can support this project with camera system and we can add LCD display to see situation of Bell that when will bell ring and what time. Bell is ringing firstly the time 8.00 am which is reminder of begining of the classes.It rings for 1 minute.Classes are 40 minutes and there is 10 minute break and 30 minutes lunch break.So i adjusted 40 minutes intervals in order to ring the bell and after 1 minute ringing it will be off.Also Bell will not ring during holidays.The time zone and holiday dates are as shown in the below;
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7.59
FB = First Bell (Begining of Classes)
8.00
P1 = Period One – 40 Minutes
8.50
P2 = Period Two - 40 Minutes
9.40
P3 = Period Three - 40 Minutes
10.20
IN = Interval - 40 Minutes
11.00
P4 = Period Four - 40 Minutes
11.50
P5 = Period Five - 40 Minutes
12.40
P6 = Period Six - 40 Minutes
13.20
LB = Last Bell - (School Over)
Holiday Dates 16 SEPTEMBER 26 SEPTEMBER 26 OCTOBER 27 OCTOBER 28 OCTOBER
Jewish New Year – Roš ha Šana Jom Kipur Eid al-Adha Eid al-Adha Eid al-Adha
25 NOVEMBER
National Day of Bosnia and Herzegovina Roman Catholic Christmas New year New year Orthodox Christmas Day of Independence of Bosnia and Herzegovina Catholic Easter Orthodox Easter International Labor day International Labor day
25 DECEMBER 1 JANUARY 2 JANUARY 07 JANUARY 1 MARCH 31 MARCH 05 APRIL 1 MAY 2 MAY
Schneider Electric SR2B121BD Zelio Compact PLC Module With the SR2B121BD Zelio Compact PLC Module, you can optimize your installation and programming expenditure and lower the costs of your application. The software ZELIO LOGIC soft 2 makes programming possible in ladder diagram or FBD (graphic functional module language). With programming in ladder diagram a program can be written with basic functions, basic function components and derived functional modules as well as wit h contacts, coils and variables. The contacts, coils and variables can be commentated, the graphics can be provided with free text The programming language FBD makes possible a graphic programming and use of pre-defined functional modules This language offers 24 pre-programmed functions such as meter, timer, clock, determination of trigger levels, pulse generator, time programs, multiplexes, etc.
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Technical data Operating voltage
24 Vdc
Type
SR2B121BD
Dimensions
(W x H x D) 71.2 x 90 x 59.5 mm
Protection type
IP20
Digital inputs
8
Power backup type
10 years
Expandable
No
Certification
CE, UL, CSA, GL,
Analogue outputs
0
Max. continuous current
250 V/AC/8 A
Analogue inputs
4*
Clock
Yes
Ambient temperature
-20 up to 55 °C
Interference suppression
According to European Economic Community 89/336 EN 61131-2 (Zone B) EN 61000-6-2,-3,-4
Digital outputs
4 relays
Mounting
Profile rail 35 mm
Display
Yes
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Wiring System Once hardware is designed cabinet box is use to c onnect PLC with school bell and motion detected alarm model. A basic wiring diagram is as shown in Figure. The PLC supplied with DC power 24V and then I/O card supplied with DC 24V. The common for input card is 24VDC. S1 which is On/Off button,S2 which is motion detector and S3 which is Reset button. Wiring system is constructed using Xtrilius 8 speaker cable for speaker.
Using a smart relay means that ordinary switches (with open or closed positions) can be used in place of two position switches. The switches are identified as S1 and S2 in the wiring diagram above. S1 and S2 are connected to inputs I1 and I2 on the smart relay. The operating principle is as follows: Each time the status of inputs I1 and I2 changes, the status of output Q1 also changes which controls the lamp L1.
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Software How to Choose PLC
Firstly we need to create new program.
Then we need to choose our model which is SR2B121BD.
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This step shows selection of extentions.No need to do anything.Just click next.
Next step is choosing program.We have to section which are Ladder Logic (LD) and Function Block Diagram (FBD) programming.I programmed my project usi ng FBD.
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Function Block Diagram PLC FBD mode allows graphic programming based on the use of predefined function blocks.In FBD programming, there are three types of windows:
The edit window, The supervision window,
Edit Window
FBD programs are created in the edit window. This window can be accesse d from the
Mode → Edit menu or by using the Edit button
in the toolbar.
The edit window is made up of three zones:
The wiring sheet, where the functions that make up the program are inserted, The Inputs zone on the left of the wiring sheet where the inputs are positioned, The Outputs zone on the right of the wiring sheet where the outputs are posit ioned.
The inputs/outputs are specific to the type of smart relay and extensions chosen by the user. The program in the edit window corresponds to the program that is:
Compiled, Transferred into the smart relay, Compared to the contents of the smart relay, Used in simulation mode, Used in supervision mode.
The following figure shows an example of a part of an edit window in FBD language:
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Description of Elements
The following table lists the different elements of the edit window: Number 1 2 3 4 5 6 7
Description Function block input zone. Connection between two function blocks. Function bar. Function block. Wiring sheet. Function block number. Output function block zone.
Supervision/Monitoring Window
The supervision/monitoring window is a subset of the edit window. . It can be accessed from:
Simulation:Mode/Simulation menu or using the simulation button on the toolbar
Monitoring:Mode/Monitoring menu or using the simulation button on t he toolbar
Function Block Diagram Application I1 is on/off button of alarm.I2 is motion detector.I3 is res et button of alarm.When i press the I1 button, alarm requires to detect a person in order to be active.When a person pass through motion detecter nearly 1 mt, alarm becomes active and indicator light activates by a motion detecter.Then at the same time audio signal alternates 2s ON, 1s OFF for 1 minute.After when we realized the alarm, we can press I3 button in order to reset alarm.
Conclusion This part summarized the concept of this project. Background part shows some basic properties of Zelio PLC like function, construction, operation, application etc. Hardware part explains very useful method of PLC application in the field. Also in this part was construction of the model, wiring system, how to choose PLC using Zelio Soft 2 program and how to simulate etc. In Software part, developed application is presented using FBD.
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Appendix A
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Appendix B Typical Boolean Instruction or Statement List
Logical functions
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TIME PROG (Daily, weekly, yearly programmer)
Description The Daily, weekly, yearly programmer validates the time ranges when acti ons can be executed. This function allows a maximum of 51 events to be defined, which are used to control its output. Outputs Output: this is the programmer validation output. When one of the cycles that has been set up as a parameter is reached, the output is active (the output remains active for the entire duration of this cycle.) Parameters In the Programming Software A cycle is defined by:
The type of action: ON or OFF, The time at which it will take effect: Hour / Minute, The activation mode.
Cycles can be activated in different ways:
Annual: Trigger of an event once per year.
In this case, the month and day must be configured.
Monthly: Trigger of an event once per month.
In this case only the day must be configured.
Date: Trigger of a single event on a specific date.
In this case, the day, month and year must be configured.
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TIMER Li (Cyclic Timing)
Description
The Cyclic timing function generates pulses (flashes) on the input rising edge.The duration of the pulse and the duration between each pulse can be set . Inputs/Outputs
The function uses a Discrete Command input. The function provides:
A Discrete-type Output, A copy of the setpoint for the pulse duration (1), The current value of the duration of the output active sta te (1), A copy of the setpoint for the duration between two pulses (1), The current value of the duration for which the output is in the inactive state (1), A copy of the setpoint (1): For the number of flashes, o Or for the duration of the flash. o The current value (1): Of the number of flashes since the first pulse, o Or of the duration of flashes since the first pulse. o (1) these integer values are displa yed in Simulation and Monitoring mode.
If the Command input is inactive, the Output is inactive and the current values are set to 0. Latching To ensure latching after a power failure in the smart relays, check the Latching box in the parameters window. Continuous flashing The figure below illustrates function operation with continuous flashing:
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Number of Flashes The figure below illustrates function operation with a defined number of flashes:
Duration of flashes The figure below illustrates function operation with predefined flash duration:
TIMER B/H (Time out)
Description
The Timer B/H function creates a pulse on the output of the rising edge of the input. Processing of the Command input depends on two types of functions:
Function B : regardless of the duration of the command pulse, the output is active for a duration that has been set, Function H : the output is inactive at the end of a set time or on the falling edge of the command.
Activation of the Reset input allows the output to be deactivated.
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Inputs/Outputs The function uses:
A discrete Command input, A discrete Reset input; this input is inactive if it is not connected.
The function provides:
A Discrete-type Output, A copy of the setpoint for the pulse duration (1), The current value of the pulse (1). (1) these integer values are displa yed in Simulation and Monitoring mode.
Latching To ensure latching after a power failure in the smart relays, you should check the Latching box in the parameters window. Function B The following figure illustrates operation with Function B set up:
Function H The following figure illustrates operation with Function H set up:
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Discrete (DISCR) Inputs
The Discrete (DISCR) Input is available for all smart relay types. The Discrete inputs can be arranged at any smart relay input. Type of Discrete Inputs The type of Discrete input can be selected from the Parameters window. This is then displayed in the edit and supervision windows.
Discrete (DISCR) Output
The smart relays feature two types of Discrete outputs:
Static outputs for certain smart rela ys supplied with DC voltage, Relay outputs for smart relays supplied with AC or DC voltage.
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Types of Discrete Outputs
The type of Discrete output can be selected from the Parameters window. This is then displayed in the edit and supervision windows. The selection is made using t he output's inactive-state symbol.
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References
1. Automating Manufacturing Systems with PLCs B (Version 4.7, April 14, 2005) Hugh Jack. 2. Programmable Logic Controllers Frank D. Petruzella 4th edition. 3. PLC Beginner Guide © 1999 Omron Asia Pasific PTE LTD. 4. http://www.electro-tech-online.com/microcontrollers/30238school-bell-controller-final-project-pic16f628a.html 5. Ideas For Old School Bells http://www.ehow.com/list_5912312_ideas-old-school bells.html#ixzz2RSalD5DE
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