Journal

International Journal of Electrical, Electronics and Computer Systems (IJEECS)
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ISSN (Online): 2347-2820, Volume -3, Issue-8, 2015
15
PLC Based Industrial DIP Painting System
1
Priyam Abhishek, 2
Deepak Kumar, 3
Jitendra Singh Tamang
1,2,3
Department of E&C Engineering, Sikkim Manipal Institute of Technology (SMIT), Majitar
Email: 1
priyam2409abhishekh@gmail.com, 2
deepakraj7879@hotmail.com, 3
js.tamang@gmail.com
Abstract: The objective is to develop software based ladder
logic for industrial dip painting system on RS LOGIX 500
software and implement the logic developed using
“ALLEN BRADELY” PLC.
In recent years, with appreciable growth in industries and
information technologies, some traditional bulk electronic
appliances have to be monitored for a long time. Control of
all such equipments has been performed through the use of
computers. Most equipments use PLC (Programmable
logic controller) to connect with computers to monitor such
consuming devices.
A PLC (Programmable Logic Controllers) is a digitally
operating electronic apparatus which uses a programmable
memory for the internal storage of instructions by
implementing specific functions such as logic sequencing,
timing, counting, and arithmetic’s. It is an easily
understood programming language and can hold data for a
long time i.e., for an indefinite time but requires excessive
work in connecting wires. Unlike general-purpose
computers, the PLC is designed for multiple input-output
arrangements, extended temperature ranges, immunity to
electrical noise, and resistance to vibration and impact.
Programs to control machine operations are typically
stored in battery-backed-up or non-volatile memory.
The present study is about the design and implementation
of industrial dip painting system based on Programmable
Logic Controller (PLC) technology. Ladder logic is
discussed briefly as a common way to program PLCs.
Keywords: PLC, ladder diagram, conveyor, trolley, relay,
industrial dip painting, RS LOGIX 500, sensors, limit
switch.
I. INTRODUCTION:
An automated system is one in which a process is
performed by a machine without the direct participation
of a human worker. There are vast opportunities for
automation in different manufacturing operations
whether the operations are related to machining or
assembling of component [8].
Earlier, painting used to be a human effort. But with the
advancements in technologies, the human effort
decrease with increase in automated machineries.
Today, industries are reluctant to waste time and money
on labours and prefer to use new technologies in order to
gain maximum output [3].
The disadvantages encountered are:
 Manual operation.
 Discontinuous operation because of manual working
less speed of operation.
 Start-up time is more.
 Less production rate.
 Unsafe working due to more manual efforts.
 High maintenance.
PLC based spray painting technology and dip coating
[6] mechanism are widely used in many industries to
overcome such problems.
Encapsulating the concepts of such technologies, we
have designed PLC based dip painting mechanism
which enables an operator to perform painting operation
with least human effort and high output efficiency.
In our project we will find how we can convert
conventional painting process with the help of PLC into
the process to evolve and admit automation as to
increase efficiency and have low error rate. It is a time
saving with good quality procedure.
TECHNICAL DETAILS:
 A PLC (Programmable Logic Controllers) [2] is an
industrial computer used to monitor inputs and based on
its program or logic, to control (turn on/off) its outputs
to automate a machine or a process. It can also be
defined as “a digitally operating electronic apparatus
which uses a programmable memory for the internal
storage of instructions by implementing specific
functions such as logic sequencing, timing and counting
through digital or analog input/output modules and
arithmetic to control” [1].
Fig 1 :- Programmable controller block diagram
 The RS LOGIX [2] software introduced for the
subject builds ladder logic programming which helps to
maximize performance, save project development time,
and improve productivity. This programming language

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has been developed to operate on Microsoft Windows
operating systems. Supporting the Allen Bradley PLC
and Micro LOGIX families of processors. RS LOGIX
500 programming package is compatible with programs
created with Rockwell Software DOS based
programming packages making program maintenance
across hardware platforms convenient and easy.
 Machine control design is a unique area of
engineering that requires the knowledge of certain
specific and unique diagramming techniques called
ladder diagramming [4]. Although there are
similarities between control diagrams and electronic
diagrams, many of the component symbols and layout
formats are different. This chapter provides a study of
the fundamentals of developing, drawing and
understanding ladder diagrams. We will begin with a
description of some of the fundamental components
used in ladder diagrams.
 Relay plays a base role in understanding the
concept of ladder logic programming. A relay, or
contactor, is an electromagnetic device composed of a
frame (or core) with an electromagnetic coil and
contacts (some movable and some fixed) [5].The
movable contacts are mounted via an insulator to a
plunger which moves within a bobbin. When the
electromagnet is energized by passing an electric current
through the coil, the magnetic field pulls the plunger
into the core, which pulls the movable contacts
downward.
Fig.2:- Structural Representation of Relay
(a) (b) (c)
Fig.3:- Relay Symbols:- (a) normally open contact. (b)
normally closed contact. (c) coil
 Timer: It basically provides a time delay given as
per user requirement
Fig 4 : TON Timer
THERE ARE 3 STATES/BITS OF A TIMER (TON):
 ENABLE (EN): Activates when the timer is
enabled.
 DONE (DN): Activates when the timer preset
value is equal to accumulator value.
 TIMER TIMING (TT): Activates till the timer
runs.
TERMS ASSOCIATED WITH TIMER:
 TIMER: Indicates the address of the timer, e.g.
T4:1.
 TIME BASE: Indicates the base of the time, e.g. 1,
0.1, 0.001.
 PRESET: Time value for which the timer runs.
 ACCUMULATOR (ACCUM): For the given
preset value, corresponding value in accumulator is
incremented.
 Counter: Counts the number of cycles involved in
an operation.
Fig 5 : Up Counter
THERE ARE 3 STATES/BITS OF A COUNTER
(CTU):
 CU: Enables when CTU is activated.
 DN: When preset value is equal to accumulator
value.
TERMS ASSOCIATED WITH COUNTER:
 COUNTER: Indicates the address of the counter,
e.g. C5:0.
 PRESET: Counts the number of cycle.
 ACCUMULATOR: For the given preset value,
corresponding value in accumulator is
incremented.
Hence, for industrial painting based on programmable
logic controller, machine has faster execution time and
is more efficient in working along with safety measures.
Unlike relay contactor logic where more hardware is
required and wiring is more complex, PLC offers
extreme understand ability. The PLC based system is
superior in performance and is more flexible due to less
complexity and being able to reconfigure through
software. Moreover, the running time get shortened due
to which desired requirement of customers gets fulfilled
by this automation.
A PLC based dip painting mechanism proposed in this
paper paints large volume containers, vehicle parts,
furniture, glasses, aluminium sheets, etc. through
automated machineries without any effective human
effort. Designed through ladder logic, the program

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enables an operator to control the entire painting
operation single handedly.
Figure 6: Proposed Model
II. METHODOLOGY:
The proposed model shown explains the Industrial Dip
Painting System and its intermediate operations.
 The trolley moves over the conveyor only when the
part is in the upper position.
 The loaded trolley is located at station-1, whose
presence is detected by sensor S1. Operator_1
presses Push Button P1 and the trolley starts to
move to the right.
 When the trolley passes through sensor S2, it stops
and the hook is lowered.
 The hanging part passes through an enclosure
labelled as "Heat Chamber". Before it leaves the
chamber, HSEN-1 (sensor) is ON and the chamber
starts heating its inside area.
 Lowering of hook is stopped when the part is
completely dipped in the paint tank, which is
sensed by the limit switch FL.
 After a predefined time of immersion, the load
hook is raised. During its upward journey, entry
inside the chamber is permitted only if the inside
temperature is raised to 150°C. The motor speed is
assumed to be 10m/sec and distance between
HSEN-1 to FL is 75 meters. Certain fixed time is
requiring elevating the temperature up to 150°C.
 The heating operation inside the chamber takes
place about 7 sec and when it comes out of the
chamber, HSEN-2 stops the heating motor and
thereby the heating process inside the chamber.
 Rising is stopped in the upper position, which is
sensed by limit switch FH.
 With the painted part, the trolley starts moving to
the right until sensor S3 senses the trolley.
 After being sensed, the painted part is off loaded
from the trolley.
 The operator_3 presses the P3 push button and the
trolley moves back to the left, referred as return
journey.
 First cycle is completed when the sensor S1 senses
the arrival of trolley back to station 1.
CONDITIONS IMPOSED:
 The paint tank needs to be filled completely before
start of the cycle. For this purpose, a pre-defined
time of 5 sec is set for filling up of tank. For this
period, there will be no operation.
 In the last cycle, a blinker starts blinking to alert
the operator that the paint tank needs to be re-
filled for further cycles. In other words, the
operator should immediately stop the operation and
start filling the paint tank.
 The temperature inside the heat chamber should be
150°C or more. Only then during rising, i.e. after
the part is painted, is allowed to enter into it.
 No sensor should affect the trolley during its return
journey, i.e., after the painted part gets offloaded
and trolley starts moving back.
 The motor speed (hook raising) is 10m/sec and
distance between HSEN1 and FL is 75 meters.
 The heating inside the heat chamber takes place for
about 7 sec.
 Even after blinking, if the operator does not stop
the operation; the whole system shuts down after
completing the cycle.

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Figure 8: Flow diagram for the proposed model.
PROGRAM: LADDER LOGIC IMPLEMENTED

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Fig 9 :- Implemented Ladder Logic for the proposed model
ADDRESS WITH CORRESPONDING FUNCTIONS:
INPUT
ADDRESS
FUNCTION
OUTPUT
ADDRESS/
BIT VECTOR
I:0/14 Fills paint tank B3:0/6
I:0/0
Senses the trolley
(S1)
B3:0/5
I:0/1 Conveyor starts B3:0/7 => O:0/0
I:0/2
Trolley stops
(S2), hook
lowering starts
O:0/5
I:0/3
Heating starts
(HSEN 1)
O:0/4
I:0/5
Hook lowering
stops
B3:0/2 => O:0/5
I:0/6
Heating stops
(FH)
B3:0/3 => O:0/4
I:0/7
Stops the entire
operation
-
I:0/12
Stops the
conveyor at
station 3 (S3)
B3:0/4 => O:0/0
I:0/13
Return journey
starts
O:0/7
DESCRIPTION :-
 Input switch 14 (I:0/14) activates bit vector 6
(B3:0/6) which in turn starts filling the paint tank
(Rung 0).

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 Bit vector 6 activates the timer T4:1 (TON) which
runs for 5 sec to completely fill the paint tank
(Rung 1).
 Input switch 0 (I:0/0) activates the bit vector 5
(B3:0.5) which senses the trolley (Rung 2).
 Input switch 1 (I:0/1) activates the bit vector 7
(B3:0/7) enabling the output 0 (O:0/0) indicating
the movement of trolley over the conveyor towards
right(Rung 3).
 Input switch 2 (I:0/2) which is normally connected
(NC), i.e., sensor S2 stops the trolley(Rung 7).
 Input switch 2 (I:0/2) which is normally open
(NO), i.e., sensor S2 starts the hook lowering(Rung
10).
 Input switch 3 (I;0/3), i.e., HSEN 1 enables output
4 (O:0/4) indicating heating operation (Rung 11).
 After output 4 is enabled, timer T4:5 (TON) is
activated for 5 sec. This time period is required to
bring the part to be painted from HSEN 1 to paint
tank (Rung 12) .
 Input switch 5 (I:0/5), i.e., FL enables the bit vector
2 (B3:0/2) and stops the hook lowering after the
part is dipped in the paint tank (Rung 9).
 DONE bit of timer T4:5 (TON) is activated which
enables timer T4:6 (TON) for 3 sec, i.e., part is
dipped inside the paint tank for 3 sec(Rung 13).
 DONE bit of timer T4:6 (TON) enables hook rising
after the part is painted (Rung 16).
 Input switch 4 (I:0/4) enables bit vector 1 (B3:0/1)
which stops the heating motor (Rung 18).
 Hook rising continues for 7 sec from heat chamber/
HSEN-1 to FL (Rung 17).
 Input switch 6 (I:0/6), i.e. FH stops the rising
operation by enabling the bit vector 3 (B3:0/3)
(Rung 14).
 Bit vector 3 (B3:0/3) enables timer T4:9 (TON)
and restarts the journey from left to right (after 4
sec) ( Rung 15).
 Input switch 12 (I:0/12), i.e., sensor S3 stops the
trolley where the painted part is off loaded (Rung
8).
 Push button P3, i.e., input switch 13 (I:0/13) starts
the return journey after the painted part is off-
loaded from the trolley (Rung 19).
 Bit vector 12 (B3:0/12) activates bit vector 10
(B3:0/10) & timer T4:10 (TON) simultaneously
which enables the return journey for 10 sec (Rung
20).
 Bit vector 10 & DONE bit of timer T4:10 activates
output 7 (O:0/7) which indicates the return journey
(Rung 21).
 Bit vector 7 enables the up counter (C5:0) which
counts the number of cycles having preset value 4
(Rung 4).
 Accumulator value of counter in rung 4 is
compared with Source B value of Equal to
operator. Depending upon the comparision made
above, bit vector 13 (B3:0/13) is enabled (Rung 5).
 Accumulator value of counter in rung 4 is
compared with Source B value of Less than
operator. Depending upon the comparison made
above, bit vector 8 (B3:0/8) is enabled (Rung 6).
 Bit vector 13 (B3:0/13) activates the timer 13 for 1
sec (Rung 25).
 DONE bit of timer T4:13 (TON) and bit vector 6
(B3;0/6) activate the output 1 (O:0/1) in blinking
mode (Rung 26).
 Output 1 (O:0/1) activates timer T4:14 (TON) to
accomplish blinking phenomena (Rung 27).
 DONE bit of timer T4:10 activates the bit vector 9
(B3:0/9) (Rung 22).
 Bit vector 9 (B3:0/9) activates timer T4:11 (TON)
(Rung 23).
 Timer timing bit (TT) bit of timer T4:11 activates
bit vector 11 (B3:0/11) to reset the timer value
(Rung 24).
 End of the ladder diagram (Rung 28).
RESULTS :-
Fig 10 : STEP 1: Idol Condition

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Fig 11 : STEP 2 : Conveyor movement starts
Fig 12 : STEP 3 : Hook Lowering starts; Conveyor
movement stops
Fig 13 : STEP 4 : Heating motor starts
Fig 14 : STEP 5 : After the part is painted, raising motor
starts
Fig 15 : STEP 6 : Raising motor stops; trolley
movement starts along with the painted part.
Fig 16 : STEP 7 :Painted part is offloaded; return
journey starts

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Fig 17 : STEP 8 : Blinking starts at the start of the last
cycle
CONCLUSION:
In recent years, with rapid growth in industries and IT
sectors, some traditional electronic appliances need to be
monitored for a long time. Control of all such
equipments has been performed through the use of
computers. Being an easily understood programming
language, most equipments use PLC (Programmable
logic controller) to connect with computers to monitor
such consuming devices.A programmable logic
controller (PLC)[5] is an electronic device used in many
industries to monitor and control building systems and
production processes. Unlike PCs and smartphones,
which are designed to perform any number of roles, a
PLC is designed to perform a single set of tasks, except
under real-time constraints and with superior reliability
and performance.
Industries today use PLC based spray painting and dip
coating mechanism. Since spray painting involves an
appreciable human effort and dip coating compromises
with product durability, the automated industrial dip
painting system introduced in this project, based on PLC
technology provides efficiency, accuracy and least
human effort with maximum effective output.
Ladder logic [9] is discussed briefly as a common way
to program PLCs. Hence a ladder logic has been
implemented to design the proposed model on RS
LOGIX 500 software. The program developed is fed to
the PLC (ALLEN BRADELY) [1] to see the system‟s
response.
REFERENCES:
[1] A Lab Manual of Allen Bradley Micrologix 1200
C series PLC.
[2] [online],”Allen-Bradley Micrologix1400 PLC”, in
https://rockwellautomation.com/
[3] Hugh Jack, “Automation Manufacturing System
with PLCs”, (Version 5.0, May 4, 2007).
[4] John R. Hackworth and Frederick D. Hackworth
Jr., “Programmable Logic Controllers:
Programming Methods and Applications”, page
no.1-2.
[5] Sanjeev Gupta and S C Sharma “Selection and
Application of advance control System: PLC, DCS
and PC Based System” Journal of Scientific and
Industrial research, April 2005, Vol.64, pp.249-
225.
[6] KsvNima Company. „Application of dip coating
with automation‟ North America, pp1-4, Oct2010.
[7] W. Bolton, Programmable Logic Controllers, Fifth
Edition, Newnes, 2009 ISBN 978-1-85617-751-1,
Chapter 1.
[8] Daniel Kandray, Programmable Automation
Technologies, Industrial Press, 2010 ISBN 978-0-
8311-3346-7, Chapter 8 Introduction to
Programmable Logic Controllers.
[9] S. S. Peng, M. C. Zhou „Ladder Diagram and Petri-
Net-Based Discrete-Event Control Design
Methods‟. IEEE Transactions on Systems, Man,
and Cybernetics- Part C, Applications and
Reviews, Vol.34 No.4 pp. 523-531 Nov. 2004.
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