pe 3231 week 15 18 plc

05/01/2023 1

Programmable Logic Controllers

PROFESSOR CHARLTON S. INAODefence UniversityBishoftu ,Ethiopia

prof CHARLTON S. INAO

PE 3231 Hydraulic Pneumatic System Design

General Objectives To explain and understand the following PLC concept:

05/01/2023 2

Programmable logic controller; Structure of PLC and system components; Programming Languages;( LAD,STL,FBD)Logic Gates application for PLCTimersCounterShift RegisterJumpProgramming Applications


05/01/2023 3prof CHARLTON S. INAO

Programmable Logic Controllers

05/01/2023 6

• Defined by NEMA as a digital electronic apparatus with a programmable memory for storing instructions to implement specific functions (logic, sequencing, timing, counting, and arithmetic) to control machines and processes.

• Considered as the first industrial-based computer


Advantages of Using PLC

05/01/2023 13

Shorter Project Implementation

Easier Modification Without Cost Penalty

Design Easily Change Using Software

Project Cost Can be Accurately Calculated

Shorter Training Time Required

A Wide Range of Control Operations

Easy Maintenance

Able to Withstand Harsh Plant Environment

High Reliability

Standardization of Controller Hardware


Functions of PLC

05/01/2023 24

Sequence Control

Conventional Relay Logic Replacer

Timer and Counter Functions

Auto / Semi / Manual Control of Machines and Processes

Sophisticated Control

Arithmetic Operations

Analog Control (Temperature, Pressure, etc.)

PID (Proportional Integral Derivation)

Stepper / Servo Motor Control


Functions of PLC

05/01/2023 25

Supervisory Control

Process Monitoring and Alarm

Interfacing with Computers

Factory Automation network

Wide Area Network


Basic Control System

05/01/2023 26

Open Loop System

INPUT LOGIC OUTPUT

- Pushbuttons- Limit Switches- Level Switches- Flow Switches

- Relays- Timers- Counter

s

- Motors- Solenoid valves- Lamps- Alarm/

annunciator- Relays/contactorsPLC


Basic Control System

05/01/2023 27

Closed Loop System

Controller Final ControlElement

ProcessVariable

Transmitter

Set value

Error

Process Variable Primary

Element / Transducer

Temperature

Flow+

_


Hardware Components

05/01/2023 28

Central Processing Unit (CPU)

Micro PLC – less than 100 I/O’s

Small PLC – 0 to 128 I/O’s

Medium PLC – 0 to 256 I/O’s

Large PLC – 0 to 512 I/O’s


Power Supply

100 – 240 Volts AC

100 / 110 Volts AC

200 / 220 Volts AC

24 Volts DC


Inputs

DC – 24 Volts

AC – 110 / 220 Volts


Outputs

Transistor type (24 Vdc )

Relay / Contact type (24Vdc / 220 Vac)

TRIAC type (110 / 220 Vac)

PNP-type Transistor Input

• Source• Generates power

NPN-type Transistor Input

• Sink• Transmits power


Relay

05/01/202332


Example: Omron Relay

05/01/202333


05/01/202334


Peripheral Devices

Programming Console

CX-Programmer Software

Conversion Cables

Connecting Cables


Software Components

05/01/2023 37

1. Ladder Diagram Language – a symbolic instruction type language

2. Boolean Language- Basic level language that composed of three (3) Boolean logic operation: AND, OR, NOT

Mnemonic Instruction – written in abbreviated form using 3 or 4 letters that generally imply the the operation of the instruction

3. Functional Blocks Language – high level instructions that permit the user to program more complex functions using the ladder diagram format

- Instruction set is composed of blocks that executes or performs specific function


4. English Statement Language – considered derivative of computer language such as BASIC.

-also known as Control Statements

Note:

OMRON PLC’s uses both Ladder Diagram Language and Boolean Language.


Key Points to Know in Selecting or Using PLC

05/01/2023 40

I. Know the process to be controlled

II. Determine the type of control

Distributed control

Centralized control

Individual machine control

III. Determine I/O interface requirements

Estimate digital and analog I./Os

Check for I/O specifications

Determine if remote I/O is required

Allow for future expansion

IV. Define peripheral devices


Steps in PLC Programming

05/01/2023 41

Draw the Schematic Diagram

Draw Control Diagram

Develop PLC Ladder Diagram

I/O Assignment

Convert to Mnemonic (Boolean)

PLC Layout


Basic Structure of PLC


PLC

Spec

ficati

ons


LOGIC GATES


AND, OR , NOT


NAND , NOR, EXOR

De Morgan’sTheorem


Boolean Algebra

• An algebraic system that describes the logic circuit, in which the variables are limited to two values, usually 0 and 1.

• George Boole developed an algebra for values for the systematic treatment of logic.

• Boolean algebra deals with variables that take on two discrete values, 0 and 1 , and with operations that assume logical meaning.

• Situations involving “yes-no, true –false,on-off” can be represented by Boolean Logical operations.


Boolean Algebra Laws1) A + 1= 12) A + 0 = A3) A.0 = 04) A.1 = A5) A + A =A6) A.A = A7)A.A = 08) A + A = 19) A + B = B + A

10) AB + AC= A(B + C)11) A + BC =(A+B)(A+C)12) A + B = A.B13) A.B = A + B14) AΦ B= A.B + A.B(exor)

15) A + AB = A + Belec

elec

elec

elec

elec

elec

elec

elec

NAND

elec

elec

OR

OR

OR

OR

AND

AND

AND

EX OR

NOR


Boolean Algebra Laws1) Anything Ored to itself is equal to itself.2) Anything ANDed to itself is equal to itself. 3) It does not matter in which order we consider

inputs for OR and AND gates.

4) We can use truth table to show we can treat bracketed terms in the same way as the ordinary algebra.

A. (B +C)=A.B + A.C A +(B.C) =( A+B) . (A+C)

A + A =A

A . A =A

A + B = B + A A . B = B . A


Boolean Algebra Laws5) Anything ORed with its own inverse equals 1. A +A =16) Anything ANDed with its own inverse equals =0 A.A=07) Anything Ored with a zero is equal to itself. Anything

Ored with a 1 is equal to 1. A + 0 =A ; A + 1= 18) Anything ANDed with a 0 is equal to zeo; anything

ended with 1 is equal to itself. A.0 = 0 A.1 = A05/01/2023 51prof CHARLTON S. INAO

Six Axioms on Properties of Boolean Algebra

Commutative Axiom:A.B=B.AA+B=B+ADistributive Axiom:A.(B+C)=(A.B) +(A.C)A+(B.C)=(A+B ).(A+C)Idempotency Axiom:A.A=AA+A=A

Absorption AxiomA.(A +B)=AA +(A.B)=AComplementation AxiomA.A=0A+A= 1A = ADe Morgan’s theorem

A.B= A + BA+B= A. B05/01/2023 52prof CHARLTON S. INAO

Programming Format

1) Ladder diagram2)Mnemonic List3) Function Block Diagram


NOR,NAND,EX-OR

05/01/2023 54

NOR

NAND

EX -OR


Timer: On delay and Off delay


TIMERS

• ON DELAY TIMER- it delays the turning on of a device by some prescribed time.(bit logic from 0 to 1)

05/01/2023 prof CHARLTON S. INAO 56

OFF DELAY TIMER


• OFF DELAY TIMER- it delays the turning OFF of a device by some prescribed time.(bit logic from 1 to 0)

Timer Resolution(Siemens)TIMER ADDRESS RESOLUTION

T32, T96 1 msT33-T36 10 ms

T97-T100 10 ms

T37-T63 10ms

T101-T255 100ms05/01/2023 prof CHARLTON S. INAO 58

Cascaded timer


Mitsubishi Siemens

On-OFF Cycle Timer


Mitsubishi Siemens

COUNTERS

Counter UPCounter DownCounter Up/Down (Bi Directional Counter)


Counter


Week 15

• Internal Relays• Markers• Two Input Internal Relay Control• Latches Control of Internal Relays• Programming Application of Internal Relays


Two Input control; Resetting a Latch


Shift Register -Mitsubishi


Shift Register


i

M 0.0

Q 0.1

Q 0.2

Q 0.3

Q 0.4

Q 0.5

Q 0.6

Q 0.7

Q 0.0

I0.1

0UT

I0.0

I 0.2

M 0.0

M 0.2

M 0.3

M 0.4

M 0.6

M 0.5

M 0.7

SFT

RST

M 0.1

Shift Register Siemens Configuration

END


Problem: Belt Sanding Machine


Transfer Station


Electric Relay Ladder Logic


Liquid Level Sorter


Wiring Diagram(Siemens LOGO)


Liquid Level Sorter Electrical Ladder Diagram


Liquid level Sorting Machine PLC Ladder Ladder Diagram

05/01/2023 82

M2.0


Artillery Cartridge Polishing Machine


05/01/2023 84

The designed and developed automated artillery cartridge polishing machine is intended for defence application to recondition the 122mm and 130mm diameter cartridges. The machine is intended to replace the traditional way of polishing the artillery cartridge with a modern and automated machine for HOMICHO Ammunition Factory. The Artillery cartridge polishing machine is a pneumatic type polishing machine which is basically used for polishing the external and internal surfaces of 122mm and 130mm artillery cartridges. The abrasive head can be moved to any point over the polishing area. The longitudinal and traverse movements of the polishing head are controlled using a programmable Language Control (PLC) integrated with pneumatically controlled cylinders. The PLC program is written using a ladder logic programming method using software for precise control of all the movements of the actuators in the two directions. Different directional control valves with pressure relieve valves are mounted to perform different functions. Standard design approaches and manufacturing sequences are followed to design and fabricate the polishing machine. The complete machine includes electric motor, pneumatic cylinders, polishing abrasives and a pneumatic line. The overall dimension of the machine is 2585x705x470mm and its spindle is designed to hold firmly different caliber cartridges and can be rotated at 800 RPM with a 5Kw spindle motor.

Since quality of the polishing machine is dependent on different polishing parameters like, polishing abrasives used, depth of polishing, RPM of the spindle and the feed rate of the polishing head, the surface quality of polished cartridges when it compared with previously polished parts it can expected to be in the range of 0.2 and 0


Cartridge polishing machine PLC Ladder diagram


The End


pe 3231 week 15 18 plc

Engineering