Controlling of PLC for Grain Storage Systems Using SCADA

International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-3, Issue-6, Jun- 2017]
https://dx.doi.org/10.24001/ijaems.3.6.13 ISSN: 2454-1311
www.ijaems.com Page | 696
Controlling of PLC for Grain Storage Systems
Using SCADA
K. Saraswathi
Assistant Professor(S-II), Department of EIE, SCSVMV University, Enthur, Kanchipuram, India
Abstract— Grain storage occupies a vital role in the
economies of developed and developing countries. Proper
monitoring of grain storage is essential to reduce grain
loss. The present system involves human effort in most of
the activities which reduces work efficiency and increases
time consumption. These difficulties can be avoided by our
proposed project. In this project, the controlling and
monitoring of the grain storage area is fully automated
using PLC and SCADA. The main objective of the proposed
project is to control and maintain the temperature in
storage area which prevents the formation of
microorganisms and spoilage of grains, to measure the
weight using a load cell placed under the conveyor belt and
to direct the different sizes of bags to their respective
storage places and to detect and control the pests, rats
using ultrasound technique. The main parameter that is
essential for proper storage of grains is temperature which
is taken as input parameter to be controlled using PLC and
is measured using a temperature sensor. The SCADA
system acquires the required data and monitors the overall
process.
Keywords—PLC, SCADA, Grain storage.
I. INTRODUCTION
We live in a world where everything can be controlled and
operated automatically, but there are still few important
sectors in our country where automation has not been
adopted or not been put to a full- fledged use, perhaps
because of several reasons one such reason is cost.
Agriculture has been one of the primary occupations of man
since early civilizations and even today manual
interventions in farming and storing grains are inevitable. In
most countries grains are among the most important staple
foods. However they are produced on a seasonal basis, and
in many places there is only one harvest a year, which itself
may be subject to failure. This means that in order to feed
the world's population, most of the global production of
maize, wheat, rice and millet must be held in storage for
periods varying from one month up to more than a year.
Grain storage therefore occupies a vital place in the
economies of developed and developing countries alike.
India is one of the largest grain producers in the world. It
produces 200 million MT (Metric tons) of wheat and rice
annually. Seventy-five percent of total grain loss occurs at
the farm level. The majority of farm level losses are driven
by inadequate storage (22%), drying of crops (15%),
transportation (12%), and threshing (10%) while the rest of
the loss scatters among several activities.
II. CONCEPT OF GRAIN STORAGE
Grain storage facilities take many forms depending on the
quantity of grain to be stored, the purpose of storage, and
the location of the store. The stored grain should be
assumed as raw material not only as a commodity. The
grain storage chain is an essential element for incrementing
the agricultural production and to preserve them in perfect
technical conditions and redistribute them later. More
grains are destroyed because of improper storage.
The requirements for a good storage system include:
• Prevention of moisture re-entering the grain after
drying
• Protection from insects
• Ease of loading and unloading
• Efficient use of space
• Ease of maintenance and management
III. EXISTING SYSTEM
One option is to store bags of grain on husks and then cover
the pile with husks. A second option involves digging a pit,
and storing bagged or loose grain covered with some husks,
mud or sacks. The third option involves building a small
cement storage facility. Automated grain storage systems
are also in practice in few places which are controlled and
monitored by personal computers.
IV. DRAWBACKS OF EXISTING SYSTEMS
The automated grain storage system existing is based on
personal computers. The major difficulties faced in such
systems involve programming and time consuming.
Loading and unloading of grains also needs human effort,

less reliability and flexibility. It is tedious to troubleshoot
and communication capabilities are less.
V. PROPOSED SYSTEM
In this project, the controlling and monitoring of the grain
storage area is fully automated using PLC and SCADA.
The main objective of the proposed project is to control and
maintain the temperature in storage area which prevents the
formation of microorganisms and spoilage of grains, to
measure the weight using a load cell placed under the
conveyor belt and to direct the different sizes of bags to
their respective storage places and to detect and control the
pests, rats using ultrasound technique. The main parameter
that is essential for proper storage of grains is temperature
which is taken as input parameter to be controlled using
PLC and is measured using a temperature sensor. The
SCADA system acquires the required data and monitors the
overall process spread out over large areas. A human
machine interface or HMI is the apparatus which presents
process data to a human operator, and through which the
human operator controls the process. An HMI is usually
linked to the SCADA system's databases and software
programs, to provide trending, diagnostic data, and
management information such as scheduled maintenance
procedures, logistic information, detailed schematics for a
particular sensor or machine, and expert-system
troubleshooting guides. SCADA software used is
IntouchWonderWare.
VI. ADVANTAGES OF PROPOSED SYSTEM
The difficulties that are faced in existing systems in
controlling and monitoring of grain storage could be
reduced by the use of Programmable Logic Controllers. A
conveyor belt is used for loading and unloading of grains
which reduces manual effort thereby increasing the
effectiveness. The enhanced features of PLC overcome
such difficulties and meet the industrial standards. The
main advantages are as follows:
Increased reliability
Easy programming and more flexibility in
modifying the program
Easy to troubleshoot
Workload is reduced and the efficiency of storage
can be reached
Faster response time and the grains could be
monitored easily.
VII. PROGRAMMABLE LOGIC CONTROLLER
A Programmable Logic Controller is a digital computer
which performs the control logic, sequencing, timing,
arithmetic data manipulation and counting functions. Unlike
general-purpose computers, the PLC is designed for
multiple inputs and output arrangements, extended
temperature ranges, immunity to electrical noise, and
resistance to vibration and impact. CPU is the brain of the
PLC, it consists of microprocessor for implementing the
logic and for controlling the communication among the
modules. Memory unit is used for storing results of logical
operations performed by the processor. IO section consists
of input modules and output modules. This system forms
the interface by which field devices are connected to the
controller. The programming device enters the desired
program into the memory of the processor. The power
supply supplies DC power to the modules. Ladder logic is
the programming language that is primarily used to develop
software for programmable logic controllers (PLCs). It
represents a program by a graphical diagram based on the
circuit diagrams of relay logic hardware. PLC used is
OMRON PLC.
VIII. SCADA
SCADA stands for supervisory control and data acquisition.
The term SCADA usually refers to centralized systems
which monitor and control entire sites, or complexes of
systems
IX. METHODOLOGY
The main operation of storing the grains is carried out
through PLC which is used as the controller and interfaced
using SCADA for monitoring the process. The required
conditions for grains to store are studied thoroughly and the
necessary temperature is maintained for the grains. The
PLC is programmed using Ladder logic programming
language.
The sensors used here are temperature sensor and IR sensor.
The input parameter temperature is sensed by the
temperature sensor (LM35) and is given as input signal to
the PLC. The PLC obtains this value through an analog
input module and compares it with the set point mentioned
in the program and decides the control action to be taken. If
the value is lower than the set point, then PLC actuates the
heater.
A conveyor belt is used for loading and unloading of grain
bags. An IR sensor is placed at the start point of the
conveyor belt. A Load cell is placed under the conveyor belt
to measure the weight of grain bags and a mechanical
separator is used for directing the grain bags based on their
sizes to their respective storage places. When a bag is

placed on the belt, the IR sensor at the starting point senses
it and the motor is switched ON thereby the conveyor
moves. When a load is applied on the load cell, the output is
generated which is given to the instrumentation amplifier.
The instrumentation amplifier acts as a signal conditioning
unit and amplifies the output of the load cell. This output is
given to the PLC which in turn drives the gear motor. This
operates the mechanical separator which directs the grain
bags of different weights to their respective storage places.
IR sensors are placed at the unloading side of the conveyor
belt in order to detect the grain bags, so that the motor is
switched OFF and the conveyor belt stops moving.
The detection and control process of rats and pests is done
using ultrasonic sound technique. An IR sensor pair is used
to detect the presence of rats and pests in the storage area.
An ultrasonic sound (sound waves with a frequency above
the upper limit of human hearing) is produced to control the
occurrence of rats and pests. NE555 IC is used for this
purpose. Ultrasonic sound wave can be generated using
electronic circuit.
SCADA (InTouchWonderware) is used for interfacing with
PLC for data gathering and monitoring, thus making the
automation process easier. This operates the mechanical
separator which directs the grain bags of different weights
to their respective storage places.
CONVEYOR SETUP
A conveyor belt is used for loading and unloading of grain
bags to their respective storage places. This conveyor setup
consists of a load cell which is placed under the conveyor
for measuring the weight of the grain bags. It also consists
of a mechanical separator which differentiates the different
sizes of grain bags according to their weight and directs
them to their respective storage places.Two IR sensors are
placed at the start and end positions of the conveyor belt.
When the IR sensor at the start position detects the grain
bag, the motor is switched ON and the conveyor starts
moving. Similarly, when the IR sensor placed at the end
position detects the grain bag, the motor is switched OFF
and the conveyor belt is stopped until the grain bags are
unloaded to their respective places.
A load cell is a transducer that is used to convert a force
into electrical signal. This conversion is indirect and
happens in two stages. Through a mechanical arrangement,
the force being sensed deforms a strain gauge. The strain
gauge measures the deformation (strain) as an electrical
signal, because the strain changes the effective electrical
resistance of the wire. The electrical signal output is
typically in the order of a few millivolts and requires
amplification by an instrumentation amplifier before it can
be used. Here the load cell is used for weight measurement.
It can measure upto 8 kgs and has four terminals namely
input positive, input negative, output positive, output
negative. A supply voltage of 5V is given to the input
positive of load cell and the input negative terminal is
grounded. Output of the load cell in millivolts is given to
input of instrumentation amplifier for signal conditioning.
When a grain bag is placed on the conveyor belt, an IR
sensor detects the grain bag. The output of the IR sensor is
below 5V, so a driver circuit is used. Driver circuit is made
with the help of ULN2803 IC. ULN2803 is an Integrated
Circuit (IC) chip with a High Voltage/High Current
Darlington Transistor Array. The chip takes low level
signals (less than 5V) as input and acts as a relay by
switching on or off a higher level signal (12V) on the
opposite side. Since the output of the IR sensor is below
5V, a driver circuit is used to give the corresponding value
(12V) as input to PLC. The output of the PLC is given to
relay for switching operation. The relay switch closes, the
gear motor starts running and the conveyor belt moves.
Load cell is placed under the conveyor belt to measure the
weight of grain bags. When a load is applied on the load
cell, the output is generated which is given to the
instrumentation amplifier. The instrumentation amplifier
acts as a signal conditioning unit and amplifies the output
of the load cell. This output is given to the PLC which in
turn drives the gear motor.
TEMPERATURE CONTROL LOOP
In the process of grain storage, temperature and humidity
are the two main factors that affect the grain quality. Insect,
mite, fungal and mycotoxin development are controlled by
temperature. At temperatures found in grain stores,
biological activity of insects, mites, fungi and grain itself,
doubles for every 10ºC rise in temperature. Traditional
methods of on-farm storage generally rely on controlling
the moisture content, and to a certain extent the
temperature, of the grain going into storage. Without proper
conditioning facilities it is unwise to attempt to store the
grain for longer than 5-8 weeks.To accurately control
process temperature without extensive operator
involvement, a temperature control system relies upon a
controller, which accepts a temperature sensor such as a
thermocouple or RTD as input. It compares the actual
temperature to the desired control temperature, or setpoint,
and provides an output to a control element. The controller
is one part of the entire control system, and the whole
system should be analyzed in selecting the proper

controller. The following items should be considered when
selecting a controller:
1. Type of input sensor (thermocouple, RTD) and
temperature range
2. Type of output required (electromechanical relay,
SSR, analog output)
3. Control algorithm needed (on/off, proportional, PID)
4. Number and type of outputs (heat, cool, alarm,
limit).
For heating control, the output is on when the temperature is
below the setpoint, and off above setpoint. Since the
temperature crosses the setpoint to change the output state,
the process temperature will be cycling continually, going
from below setpoint to above, and back below. In cases
where this cycling occurs rapidly, and to prevent damage to
contactors and valves, an on-off differential, or “hysteresis,”
is added to the controller operations. This differential
requires that the temperature exceed setpoint by a certain
amount before the output will turn off or on again. On-off
differential prevents the output from “chattering” or making
fast, continual switches if the cycling above and below the
setpoint occurs very rapidly.
Table.1: Effect of different temperatures on pests
TEMPERATURE EFFECT ON PESTS
30 Maximum development rate
35 Development slows
45 Development stops
50 Death in hours
60 Death in minutes
The temperature inside the storage area is measured using
temperature sensor, LM35. The output of the sensor is given
to the PLC and is compared with the set point value of the
PI controller. The values are compared and the error is
calculated. The analog output from the controller is
converted into TPO(Time Proportional Output). The heater
coil is switched ON and OFF at the required rate and the
heating is controlled to reach the set point. If the
temperature exceeds set point, the heater coil temperature is
reduced to control overheating. A blower is used to suck the
air from outside and this air is heated by the heater in order
to maintain the temperature in the storage area.
Wave with frequency range of 36 to 72 kHz. It is very easy
and quick to make this circuit. This circuit uses NE555 IC
timer to drive a speaker. If a moving coil tweeter is used,
then it is recommended to add a decoupling capacitor
around 1uF-2.2uF/16V to block the DC voltage. For adding
a circuit safety, a 1k resistor is inserted between R2 and the
positive supply line, since the pin 7 of 555 IC will be
internally shorted to ground at the discharging cycle.
Fig.1: Temperature control loop
RAT DETECTION AND CONTROL
Ultrasound is cyclic sound pressure with a frequency
greater than the upper limit of human hearing. Ultrasound is
thus not separated from "normal" (audible) sound based on
differences in physical properties, only the fact that humans
cannot hear it. The upper frequency limit in humans
(approximately 20 kHz) is due to limitations of the middle
ear, which acts as a low-pass filter. Ultrasonic hearing can
occur if ultrasound is fed directly into the skull bone and
reaches the cochlea through bone conduction without
passing through the middle ear. Many animals—such as
dogs, cats, dolphins, bats, and mice—have an upper
frequency limit that is higher than that of the human ear and
thus can hear ultrasound. The use of ultrasonic devices in
pest control would be a potential source of environmental
friendly technology because ultrasound is clean and non-
chemical. Rodents can hear the sound that humans cannot.
They can produce and hear ultrasound (sound waves with a
frequency above the upper limit of human hearing). The
ultrasonic devices for rodent control are practically
inaudible to humans with their output frequencies above 20
kilohertz (kHz). They produce ultrasonic noise so aversive
to rodents that it drives rodents away.
Ultrasonic sound wave can be generated using electronic
circuit. This simple electronic circuit can generate an
ultrasonic

Fig.2: Ultrasonic sound wave generator
DESIGN CALCULATION
T = 0.693*(R1+2*R2)* C1
f = 1/T = 1.44/(R1+2R2)*C1
If C1 = 0.001 µF, R2 = 10
KΩ, When R1 = 20 KΩ,
f =
1.44/(40×10³×0.001×10¯6
) f = 36 KHz.
When R1 = 0 KΩ,
f =
1.44/(20×10³×0.001×10¯6
) f = 72 KHz.
Hence frequency range is 36 KHz to 72 KHz
PROCESS SETUP
The main operation of storing the grains is carried out
through PLC which is used as the controller and interfaced
using SCADA for monitoring the process. The required
conditions for grains to store are studied thoroughly and the
necessary temperature is maintained for the grains. The
PLC is programmed using Ladder logic programming
language. In this project, the controlling and monitoring of
the grain storage area is automated using PLC and SCADA.
The main objective of the proposed project is to control and
maintain the temperature in storage area which prevents the
formation of Microorganisms and spoilage of grains, to
measure the weight using a load cell placed under the
conveyor belt and to direct the different sizes of bags to
their respective storage places and to detect and control the
pests, rats using ultrasound technique.
The main parameter that is essential for proper storage of
grains is temperature which is taken as input parameter to
be controlled using PLC and is measured using a
temperature sensor. The SCADA system acquires the
required data and monitor sthe overall process
Fig.3: Block diagram of final setup
X. SIGNAL CONDITIONING OF LOAD CELL
The output of the load cell is given to an instrumentation
amplifier (INA122) in order to amplify the measured value.
The output side of the instrumentation amplifier consists of
a resistor and a capacitor of values 10 KΩ and 100 µF
respectively. The amplified output is the voltage drop across
the 10 KΩ resistor which is given to the PLC to drive the
gear motor. The 100 µF capacitor is used as a filter to
reduce the noise and eliminate the unwanted signals.

XI. IR SENSOR
object, as well as detect motion. Many of these types of
sensors only measure infrared radiation, rather than emitting
it, and thus are known as passive infrared (PIR) sensors.
All objects emit some form of thermal radiation, usually in
the infrared spectrum. This radiation is invisible to our eyes,
but can be detected by an infrared sensor that accepts and
interprets it. In a typical infrared sensor like a motion
detector, radiation enters the front and reaches the sensor
itself at the center of the device.
Fig.4: IR sensor working principle
XII. INSTRUMENTATION AMPLIFIER
An instrumentation amplifier is a type of differential
amplifier that has been outfitted with input buffers, which
eliminate the need for input impedance matching and thus
make the amplifier particularly suitable for use in
measurement and test equipment.
XIII. CALCULATION OF GAIN
The Gain of the amplifier can be set externally by using a
resistance
Rg.
Gain, G = 5 + (20 k/ Rg)
WhenRg=50Ω,
Gain, G= 5 + (20 k/50)
Gain, G= 405
The basic idea is to send infrared light through IR-LEDs,
which is then reflected by any object in front of the sensor.
An infrared sensor is an electronic device that emits and/or
detects infrared radiation in order to sense some aspect of
its surroundings.
XIV. SCADA SCREEN
XV. CONCLUSIONS
The grain storage technique is of great importance in India
in future and to globalise our standards in agriculture. The
technology in India has to be enhanced. Our aim was to
utilize the learnt instrumentation principles and put that into
use so that it will improve the standards of our nation. India
still has to improve its automation techniques especially in
the field of agriculture. We used our knowledge in
programmable logic controllers and wanted to use it for a
cause that would help in the betterment of our nation. We
made research on different grain storage techniques to
know the desiarable conditions for proper storage, and then
we decided the parameters to be mainly monitored and the
required ways of controlling them.
The loading and unloading of grain bags in the grain
storage area is done by the use of a conveyor belt. A load
cell is placed under the conveyor belt to measure the weight
of the grain bags and also to have a count on total number
of bags in the storage area. A mechanical separator directs
the grain bags to their respective storage places based to
their sizes. This reduces human effort and also saves time.
The temperature in the grain storage area is also monitored
and controlled automatically. The occurrence of rats and
pests in the storage area is controlled by ultrasound
technique. SCADA software is used for real time
monitoring of these processes.

REFERENCES
[1] “Programmable Logic Controllers”, Frank .D.
Petruzella.
[2] Supervisory Control And Data Acquisition
(SCADA) basics,
“http://en.wikipedia.org/wiki/SCADA”.
[3] Electronic Pest Control,
http://en.wikipedia.org/wiki/Electronic_pest_cont
rol”.
[4] INA122 Instrumentation Amplifier data sheet.
[5] LM35 Temperature sensor data sheet.
[6] Gear motor working principle,
“http://www.ehow.com/about-gear-motor”.

Controlling of PLC for Grain Storage Systems Using SCADA

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