Dr. HABEEB HATTAB HABEEB Dr. HABEEB HATTAB HABEEB Office: BN-Block, Level-3, Room Ext. No.: 7292 UNITEN University TENAGA Nasional Lecturer: Habeeb Al-Ani Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

U niversity TENAGA National College Of Engineering Mechanical Department Academic Year – Lecture Note UNITEN University TENAGA Nasional Lecturer: Habeeb Al-Ani Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

CAM University TENAGA Nasional Lecturer: Habeeb Al-Ani Computer Aided Manufacturing UNITEN Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

4 PLC: Programmable Logical Controller 1. What is PLC 2. Relay-Device 3. PLC Architecture 4. Programming a PLC Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

5 What does PLC stand for?  PLC - programmable logic controller  PLC implements logic control functions by means of a program Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

6 PLC - programmable logic controller Programmable Logic Controller (PLC) is a microprocessor based system that uses programmable memory to store instructions and implement functions such as logic, sequencing, timing, counting and arithmetic in order to control machines and processes. The first PLC was developed in 1969 by General Motors. Microprocessor-based PLC was introduced in 1977 by Allen Bradley. Definition of PLC Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

7 PLC - programmable logic controller PLC is viewed as a solid-state: - Digital - Industrial computer PLC is made to fit an industrial environment and for exposure to hostile conditions, such as: - Heat - Humidity, - Unreliable power - Mechanical shocks and vibrations. Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

8 Unlike Personal Computer, PLC does not contain, such as display or keyboard, that allow user to directly interact with PLC. In order to facilitate interaction, separate computer is provided, normally taking form of a standard PC. Through this external computer, operator can re-program PLC, provide set-points and view trends of process variables that are controlled and manipulated by PLC. PLCActuatorProcess Sensor External Computer PLC - programmable logic controller Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

Before the invention of the Programmable Logic Controller (PLC), most industrial control was done using relay control panels. Switches and relays can be arranged in circuits to make logical decisions. Output from Relay can be used with the following components: 1. Drive “loads” such as motors 2. Heaters, or electromagnetic coils. A relay control panel is comprised of a single to thousands of these circuits. Relay-Devise Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

Input relays: These are connected to the outside world. They physically exist and receive signals from switches, sensors,etc. - Internal Utility Relays: They are simulated relays that are dedicated to performing only one task.. Some are on only during power on and typically used for initializing data that was stored. Output Relays: These are connected to the outside world. They physically exist and send on/off signals to solenoids, lights,etc. They can be transistors, relays etc. Relays types Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

Relays and Schematic Symbols

12 PLC consists of the following components: 1.Microprocessor – This is the brain of PLC. It reads input signals, executes control program and communicates results (decisions) of control program as action signals to the outputs. 2.Memory – It stores control program that is to be executed at a prescribed rate. 3.Power Supply – This component is used to convert the mains AC voltage to the low DC voltage (e.g. from 240V AC to 5V DC). Programmable Logic Controller Architecture Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

13 PLC consists Con... 4.Input Module – This component receives information from external devices (sensors). It contains circuitry that provides electrical isolation and signal conditioning functionalities. Input module can be analogue input (AI) or discrete input (DI) module. 5.Output Module – This module communicates control actions to external devices (actuators). It contains circuitry required to interface PLC with actuators (e.g. digital-to-analogue converter and power amplifier). 6. Communication Module – This component allows PLC to communicate with external devices using sophisticated multiple-bit digital communication protocols (e.g. Ethernet). Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

Power Supply Communication Module Microprocessor + Memory Analogue Input (AI) Module Discrete Output (DO) Module Discrete Input (DI) Module Analogue Output (AO) Module Analogue Sensor Discrete Sensor Analogue Actuator Discrete Actuator Operator Workstation Programmable Logic Controller Architecture PLC Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

(PLC) Samples Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

16 Inputs Outputs & Power Supply Communication Ports (RS-485) Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

17 Where are PLCs used?  In every industry where automation is involved, from individual machines to whole processes Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

18 PLC Applications Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

19 PLC - Introduction An application example 1: Gate Control  PLC can sense a vehicle at the entrance or exit, and open and close the gate automatically  The current vehicle count is easily determined by programming a simple counter Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

20 An application example 2: Conveyor System  PLC can be used to start/stop latching logic for motor control  Counters can be used for monitoring product amounts Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

21 Why? PLC differ from a computer?  A computer is optimized for calculation and display tasks  A computer is programmed by specialists  A PLC is designed for (logic) control and regulation tasks  A PLC is programmed by non-specialists  A PLC is well adapted to industrial environment Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

22 Why are PLCs so common?  They are cost-effective  They are flexible, reliable and compact  They have significant advantages over traditional control systems based on relay or pneumatics Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

23 What tasks do PLCs perform?  The logic control tasks such as interlocking, sequencing, timing and counting (previously undertaken with relays or pneumatics)  In addition, PLCs can perform a variety of calculation, communication and monitoring tasks Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

24 The PLC processor Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

25 PLC Input/Output Devices Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

26 PLC Input Devices  Push buttons  Switches (limit switches, level switches, etc.)  Sensors ... Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

27 PLC Output Devices  Relay contacts  Solenoid valves  Signal devices (such as lamps, alarms, etc.)  Motors ... Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

28 Programming terminal Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

29  Programming is done through programming terminal  Programming terminal translates engineering language (logic control) to machine language (binary code) Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

30 Programming through standard computer  Most PLC manufacturers offer software packages that allow a standard computer to be used as a programming terminal Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

31 Programming through standard computer Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

32 Program steps- to inputs and outputs  The CPU reads the data from the inputs  The program in the CPU uses the inputs to evaluate the control logic. As the program runs, the CPU updates the data  The CPU writes the data to the output Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

33 Data Flow in the PLC Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

34  One of the advantages of PLC is that it can be programmed by non-specialists  Program can be written either in the form of a statement list: a set of mnemonic instructions representing a function of the CPU or a ladder diagram: a graphical language resembling the electrical relay diagrams Advantages of PLC Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

35 PLC Forms: 1.Rack 2.Mini 3.Shoebox 4.Micro 5.Software Lecturer: Dr. HABEEB ALANI University TENAGA Nasional

University TENAGA Nasional Lecturer: Habeeb Al-Ani Lecturer: Dr. HABEEB ALANI University TENAGA Nasional