A presentation made at A 2-day Annual Symposium, organized by Electrical/Electronic Engineering Department, FUTO, at School of Engineering and Engineering Technology (SEET) Complex Auditorium, FUTO, Imo State. (August 18, 2016)

1. INDUSTRIAL AUTOMATION USING PLC
Iroakazi Chidiebere
PZ Cussons Nigeria Plc
kazzika@yahoo.com

2. Outline
Introduction
Background
PLC definition
PLC manufacturers
PLC Programming software
How it works
Advantages & Disadvantages
Application
Ladder logic
Conclusions and Recommendations
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3. Introduction
The Programmable Logic Controller (PLC) has
revolutionized the automation industry. Today PLCs can be
found in everything from factory equipment to
Automobiles, but prior to 1968 the programmable
controller didn’t even exist. Instead what existed was a
unique set of challenges that needed a solution.
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4. Background
Before the days of the PLC the only way to control machinery
was through the use of relays.
For example if I wanted to control an electric motor, I could
attach a relay between the power source and the motor. Then
I could control when the motor is getting power by either
energizing or de-energizing the relay.
There could be several motors in one factory that need to be
controlled, so what do you do? You add lots of relays.
So factories started to amass electrical cabinets full of power
relays
To effect any changes, electricians would have go through the
herculean task of rewiring each relays ”Five hours to find it
and five minutes to fix it”
In 1968 the Hydramatic Division of the General Motors
Corporation specified the design criteria for the first
programmable controller
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5. GM Hydra-Matic Mandate
PLC
Less
wiring/User
friendly
Cost
effective
Extensive I/O
capability
Robust and able
to withstand
extreme
operating
conditions
Extraordinary
processing
time

6. Dick Morley’s company Bedford Associates in
Massachusetts proposed something called a Modular
Digital Controller (MODICON).
The MODICON 084 brought the world’s first PLC into
commercial production.
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PLC Pioneers

7. A Programmable Logic Controller (PLC) is
an electronic device with a Programmable
memory, multiple input and output
terminals that is used to logically control
various industrial machines and processes
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What is a PLC?

8. Major Components of a PLC
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PROCESSOR
POWER
SUPPLY
I M
N O
P D
U U
T L
E
O M
U O
T D
P U
U L
T E
PROGRAMMING
DEVICE
From
SENSORS
Pushbuttons,
contacts,
limit switches,
etc.
To
OUTPUT
Solenoids,
contactors,
alarms
etc.

9. Major Components of a PLC
POWER SUPPLY
– Provides the voltage needed to run the primary PLC
components
I/O MODULES
– Provides signal conversion and isolation between the
internal logic-level signals inside the PLC and the field’s high
level signal.
PROCESSOR
– Provides intelligence to command and govern the activities
of the entire PLC systems.
PROGRAMMING DEVICE
– used to enter the desired program that will determine the
sequence of operation and control of process equipment or
driven machine.
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10. Leading Brands Of PLC
AMERICAN 1. Allen Bradley
2. Modicon
3. Texas Instruments
4. General Electric
EUROPEAN 1. Siemens
2. Festo
3. Telemechanique
JAPANESE 1. Toshiba
2. Omron
3. Mitsubishi
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11. PLC Programming Software
Allen-Bradley – Rockwell RSLogix500/5000
Modicon - Modsoft
Omron – CX-ONE
Siemens– Simatic Step 7
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12. How Does it work?
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Self
scan
•Testing of its
own hardware
and software for
faults
Input
scan
•A PLC scan cycle
begins with the
CPU reading the
status of its
inputs.
Logic
scan
•The application
program is
executed using
the status of the
inputs
Output
scan
•The cycle ends by
updating the
outputs.
PLC SCAN CYCLE

13. Concept of Ladder logic
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Power flows through these contacts when they are closed. The
normally open (XIC) is true when the input or output status bit
controlling the contact is 1. The normally closed (XIO) is true
when the input or output status bit controlling the contact is 0.
Examine if open
(XIC)
Examine if closed
(XIO)

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On Delay Timers (TON) EN
DN
TT:
PRESET:
ACC:
EN: This is the timer Enable bit that comes on once the timer
is energised
DN: This is the timer Done bit that only comes on once the
time is done counting
TT: This is the Timer Timing bit which comes on and stays on
as long as the timer is counting and goes off once the timer is
done counting.

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Coils
Coils represent relays that are energized when power flows to
them. When a coil is energized it causes a corresponding
output to turn on by changing the state of the status bit
controlling the output to 1

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AND OPERATION
Rung
Each rung or network on a ladder program represents
a logic operation. In the rung above, both inputs A and B
must be true (1) in order for the output C to be true (1).

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OR OPERATION
Rung
In the rung above, it can be seen that either input A or B
is be true (1), or both are true, then the output C is true (1).

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NOT OPERATION
Rung
In the rung above, it can be seen that if input A is be true (1),
then the output C is true (0) or when A is (0), output C is 1.

19. Tank Used to Mix Two Liquids
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A
B
C
FS
MOTOR
TIMER

20. Tank Used to Mix Two Liquids
A tank is used to mix two liquids. The control circuit operates as
follows:
When the start button is pressed, solenoids A and B energize.
This permits the two liquids to begin filling the tank.
When the tank is filled, the float switch trips. This de-energizes
solenoids A and B and starts the motor used to mix the liquids
together.
The motor is permitted to run for one minute. After one minute
has elapsed, the motor turns off and solenoid C energizes to
drain the tank.
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21. Tank Used to Mix Two Liquids
When the tank is empty, the float switch de-energizes
solenoid C.
A stop button can be used to stop the process at any
point.
Once the circuit has been energized it will continue to
operate until it is manually stopped.
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22. Sample Program
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23. 7/8/201723
Smaller in size
Cost Effective
Ease of maintenance/
troubleshooting
Rugged and reliable
Easier and faster to make changes
High Speed of Operation
Diagnosis can be centrally
available
Advantages

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Hard wired VS PLC

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PLC devices are proprietary
Disadvantage

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Oil & Gas processing Plants
Factory/Process automation
Warehouse Automation
Traffic management controls
Power systems
Water treatment systems
Applications

27. Conclusions & Recommendations
As industrial automation evolves, students
exposure to modern technologies will translate
to increased opportunities in different industries,
therefore it is expedient that our universities put
in place a compulsory scheme on Factory
Automation that ensures every engineering
graduate gets a feel of what automation is all
about before graduation. Lagos state has already
started this by implementing a FESTO
Authorized and Certified Training (FACT) Centre

28. Thank you
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