PLC Programmable Logic Controller Prepared by Tahmid Rongon and Ahad hossain
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PLCProgrammable Logic Controller
Prepared by
Tahmid Rongon and Ahad hossain
CONTENT History What is PLC ? Why PLC ? Architecture of a PLC Components Programing Language
Of PLC Ladder Logic Programming Example Block Diagram
Our Project Circuit Project video Advantage Disadvantage Area of Applications Conclusion Summery References
HISTORY PLC was introduced in late 1960’s. First commercial and successful programmable
logic controllers was designed and developed by modicon as a relay replacer for General Motors.
Earlier , it was a machine with thousand of electronic parts.
Later in late 1970’s the microprocessor became and greatly enhanced the role of PLC permitting it to evolve from simply relay to the sophisticated system as it is today.
WHAT IS PLC?
The automation of many different processes , such as controlling machines or factory assembly lines, is done through
the use of small computers called a programmable logic controllers(PLCs).
Programmable Logic Controller (PLC) is an industrial computer that monitors inputs, makes decisions based on its program and controls outputs to automate a process or machine.
WHY PLC? To reduce human efforts . To get maximum efficiency
from machine and control them with human logic .
To reduce complex circuitry of entire system .
To eliminate the high costs associated with inflexible, relay-controlled systems.
ARCHITECTURE OF A PLC
INPUT
Power Supply
PLC OUTPUT
MEMORY INTERFACE
COMPONENTS
COMPONENTS INPUT MODULES accepts and converts signals from sensors
into a logic signal Ex. : Switches, Pushbuttons. OUTPUT MODULES that convert control instructions a signal
that can be used by actuators. Ex. : lamps, alarm.
INPUT (PUSH BUTTON ) PLC OUTPUT (INDICATOR LIGHT)
PROGRAMING LANGUAGE OF PLC Most common languages
encountered in PLC programming are:
1) Ladder Logic. 2) Functional Block Diagram. 3) Sequential Function Chart. 4) Boolean mnemonics.
LADDER LOGIC The ladder logic is the oldest programming
language for PLC. It is well suited to express Combinational logic. The main ladder logic symbols represent the
elements :
PROGRAMMING EXAMPLE:Ladder Logic Program for Start/Stop of Motor :
BLOCK DIAGRAM OF OUR PROJECTLiquid-1 Liquid-2
MixtureTank
DumpTank
OUR PROJECT Automatic liquid mixing machine for industrial use.
CIRCUITNeutral Mood
CIRCUITLiquid Coming Mood
CIRCUITMotor Starting Mood
CIRCUITDump Mood
AREA OF APPLICATION Machine controls
AREA OF APPLICATION Machine controls Food/Beverage processing
AREA OF APPLICATION Machine controls Food/Beverage processing Car park & Train station control system.
AREA OF APPLICATION Machine controls Food/Beverage processing Car park & Train station
control system. Manufacturing, Packaging,
Palletizing
AREA OF APPLICATION Machine controls Food/Beverage processing Car park & Train station
control system. Manufacturing, Packaging,
Palletizing Material handling
AREA OF APPLICATION Machine controls Food/Beverage processing Car park & Train station
control system. Manufacturing Packaging, Palletizing Material handling Textile,Travel,printing Industry similar Sequential task as well as
Process control etc.
ADVANTAGES very Fast , High speed of operation. Small physical size, shorter project time Reduced space. inputs and outputs already inside the controller. Low power consumption designed to withstand vibrations,temperature,humidity,noise
etc. Easy maintenance due to modular assembly and flexibility Improves Productivity Improves Quality
DISADVANTAGESInitial Costs Are HighPLC hold only one copy of programmesPLC Devices Are ProprietaryUnemployment Rate IncreasesThere's difficulty with changes or replacements.When a problem occurs, hold-up time is
indefinite, usually long, It's always difficult to find errors.
CONCLUSIONThe PLC have in recent years experienced an
unprecedented growth as universal element in industrial automation .
It can be effectively used in applications ranging from simple control like replacing a small number of relays to complex automation problems.
Today the PLCs are used for control & automation job in a single machine & it increases up to full automation of manufacturing / testing process in a factory.
SUMMARY In this presentation we have discussed about:What is PLC.Why we use PLC.Description of PLC.A project over PLC.Area of application.Advantages & disadvantages
REFERENCESWikipediaIndustrial Control Handbook, Industrial Press Inc.W. Bolton, Programmable Logic Controllers, Fifth
Edition. Maher, Michael J. Real-Time Control and
Communications.
ANY QUESTION
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