Pe 3231 week 15 18 plc

1/22/2016 1
Programmable Logic
Controllers
PROFESSOR CHARLTON S. INAO
Defence University
Bishoftu ,Ethiopia
prof CHARLTON S. INAO
PE 3231 Hydraulic Pneumatic
System Design

General Objectives
To explain and understand the following PLC concept:
1/22/2016 2
Programmable logic controller;
Structure of PLC and system components;
Programming Languages;( LAD,STL,FBD)
Logic Gates application for PLC
Timers
Counter
Shift Register
Jump
Programming Applications

1/22/2016 3prof CHARLTON S. INAO

Programmable Logic Controllers
1/22/2016 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
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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
1/22/2016 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
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Supervisory Control
Process Monitoring and Alarm
Interfacing with Computers
Factory Automation network
Wide Area Network

Basic Control System
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Open Loop System
INPUT LOGIC OUTPUT
-Pushbuttons
-Limit Switches
-Level Switches
-Flow Switches
-Relays
-Timers
-Counters
-Motors
-Solenoid valves
-Lamps
-Alarm/annunciator
-Relays/contactors
PLC

Basic Control System
1/22/2016 27
Closed Loop System
Controller
Final Control
Element
Process
Variable
Transmitter
Set value
Error
Process
Variable Primary
Element / Transducer
Temperature
Flow
+
_

Hardware Components
1/22/2016 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
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32

Example: Omron Relay
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33

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34

Peripheral Devices
Programming Console
CX-Programmer Software
Conversion Cables
Connecting Cables

Software Components
1/22/2016 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
1/22/2016 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
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Draw the Schematic Diagram
Draw Control Diagram
Develop PLC Ladder Diagram
I/O Assignment
Convert to Mnemonic (Boolean)
PLC Layout

Basic Structure of PLC

PLCSpecfications

LOGIC GATES

AND, OR , NOT

NAND , NOR, EXOR
De Morgan’s
Theorem

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 Laws
1) A + 1= 1
2) A + 0 = A
3) A.0 = 0
4) A.1 = A
5) A + A =A
6) A.A = A
7)A.A = 0
8) A + A = 1
9) A + B = B + A
10) AB + AC= A(B + C)
11) A + BC =(A+B)(A+C)
12) A + B = A.B
13) A.B = A + B
14) AΦ B= A.B + A.B(exor)
15) A + AB = A + B
elec
elec
elec
elec
elec
elec
elec
elec
NAND
elec
elec
OR
OR
OR
OR
AND
AND
AND
EX OR
NOR

1) 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

5) Anything ORed with its own inverse equals 1.
A +A =1
6) Anything ANDed with its own inverse equals =0
A.A=0
7) Anything Ored with a zero is equal to itself. Anything
Ored with a 1 is equal to 1.
A + 0 =A ; A + 1= 1
8) Anything ANDed with a 0 is equal to zeo; anything
ended with 1 is equal to itself.
A.0 = 0
A.1 = A1/22/2016 51prof CHARLTON S. INAO

Six Axioms on Properties of Boolean Algebra
Commutative Axiom:
A.B=B.A
A+B=B+A
Distributive Axiom:
A.(B+C)=(A.B) +(A.C)
A+(B.C)=(A+B ).(A+C)
Idempotency Axiom:
A.A=A
A+A=A
Absorption Axiom
A.(A +B)=A
A +(A.B)=A
Complementation Axiom
A.A=0
A+A= 1
A = A
De Morgan’s theorem
A.B= A + B
A+B= A. B1/22/2016 52prof CHARLTON S. INAO

Programming Format
1) Ladder diagram
2)Mnemonic List
3) Function Block Diagram

NOR,NAND,EX-OR
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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)
1/22/2016 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 ms
T33-T36 10 ms
T97-T100 10 ms
T37-T63 10ms
T101-T255 100ms1/22/2016 prof CHARLTON S. INAO 58

Cascaded timer
Mitsubishi Siemens

On-OFF Cycle Timer
Mitsubishi Siemens

COUNTERS
Counter UP
Counter Down
Counter 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
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M2.0

Artillery Cartridge Polishing Machine

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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

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Pe 3231 week 15 18 plc