LOW COST SCADA SYSTEM FOR EDUCATION

Low cost SCADA system for education
Alan Kardek Rêgo Segundo, José Alberto Naves Cocota Junior, Rárisson Queiroz Hilário, Vinícius de Oliveira Gomide,
Diógenes Viegas Mendes Ferreira
Departamento de Engenharia de Controle e Automação e de Técnicas Fundamentais - DECAT
Escola de Minas, Universidade Federal de Ouro Preto - UFOP
Ouro Preto, Brasil
alankardek@em.ufop.br, cocota@em.ufop.br, rarimhilario@gmail.com, viniciusgomide@yahoo.com.br,
diogenes_viegas@ymail.com
Abstract— A prototype based on SCADA system was
developed as a result of the final project of the discipline entitled
Applied Microcontrollers to Control and Automation
Engineering. This course has project based learning (PBL)
methodology. The prototype has a drive unit and a computer
program. This device was developed using a PIC18F4550
microcontroller and various electronic components: resistors,
capacitors, LEDs, among others. The computer program was
developed using programming language C Sharp (C #) in Visual
Studio development environment. The interface between the
program and the device is performed via USB communication.
This prototype is now used in the discipline mentioned in order
to teach practical lessons about embedded systems projects, USB
communication, data acquisition and supervisory systems. As all
stages of the project were presented to the students in a very
detailed way and its development was performed on a real
application, the students showed a lot of interest about this tool
during the last school year.
Keywords—Project Based Learning; Microcontroller;
Supervisory System.
I. INTRODUCTION
The use of educational tools for conducting laboratory
classes might stimulate student interest. This is due the fact
that the theoretical issues observed in the classroom are
presented in practice. However, these systems often have a
high price and closed architecture, which prevent the student
to understand how the system was developed.
The Project Based Learning (PBL) methodology is
considered one of the most effective ways for the student to
obtain the ability to solve problems. The proposal for a
project to solve an engineering problem motivates and
stimulates both the students and the professor. Furthermore,
this methodology prepares students for the market, as it
promotes the development of leadership skills, decision
making, time planning, teamwork, conflict resolution and
synthesis of results on students [1, 4].
SCADA systems are generally used to ensure process
quality, reduce operating costs and improve production
performance. Furthermore, the centralization of all
information about the production process in a single system
might facilitate the analysis to improve the company.
References [2, 3] also show the development of low cost
SCADA systems.
The Microcontrollers Applied to Control Engineering and
Automation discipline was created in 2012 in order to
establish the theoretical content seen in the undergraduate
course of Control and Automation Engineering from Federal
University of Ouro Preto through the methodology of project
based learning (PBL). Since then the discipline has aroused
much interest in the students and contributed to the
development of several final course works. In fact, the system
presented in this article was the result of the final work
discipline conducted by a group of students. In later periods,
this system has been used as an example during practical
classes.
This paper presents the development of a low cost SCADA
system to be used to teach embedded systems projects, USB
communication, data acquisition and creation of supervisory
systems.
II. PROTOTYPE DEVELPMENT
This work was developed in the Electrical Machines
Laboratory of the Department of Control and Automation
Engineering and Fundamental Techniques in the School of
Mines, a unit of the Federal University of Ouro Preto. The
prototype was designed in two stages: (i) development of
supervisory computer program and data acquisition; and (ii)
development of a drive unit and interface device.
A. Supervisory computer program and data acquisition
The program user interface was developed in the C#
programming language via the Visual Studio IDE. In
developing this program, the team was seeking to provide a
friendly graphical user interface. The analog process variables
can be displayed by means of gauges and graphics. The
change of the state of digital variables can be perceived by the
change of color of a symbol that identifies this variable. The
load drive can be accomplished through the click of a button.
The button colors indicate whether the device is on or off. In
addition, the system provides analog outputs, which can easily
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978-1-4799-1908-6/15/$31.00 ©2015 IEEE 18-20 March 2015, Tallinn University of Technology, Tallinn, Estonia
2015 IEEE Global Engineering Education Conference (EDUCON)

have their values changed by adjusting the bars in progressive
supervisory program.
This program also performs data acquisition, allowing the
user to save the state of the system variables over time in a
text file or an Excel spreadsheet. The Fig. 1 shows the
simplified flowchart of this software.
B. Drive unit and interface device
The drive unit and interface device was developed using a
PIC18F4550 microcontroller and various electronic
components such as resistors, capacitors, buttons,
potentiometers, LEDs, among others. The Fig. 2 shows the
electronic design of this device.
This device presents: two analog and four digital inputs;
two analogue and six digital outputs; USB interface; recording
circuit for ICSP (In Circuit Serial Programming); connector
for communication UART (Universal Asynchronous Receiver
or Transmitter); and eight-pin port can be used as either digital
inputs or digital outputs.
The microcontroller firmware was developed in the C
programming language. The data on the state of digital input
ports and values of the analog-digital conversion result are
sent via USB to the supervisory program at intervals of
100ms. The control commands from supervisory program are
sent asynchronously according to the user decisions. The Fig.
3 shows the simplified firmware flowchart.
The Figs. 4 and 5 show the design of the printed circuit
board (PCB) of this device. The Fig. 6 shows a 3D view of the
board. This view shows more clearly how the elements are
distributed. The PCB was manufactured by the method of
thermal transferring. The holes were made using a power drill
bench and the elements were soldered using a soldering
station.
Start
Graphical interface initialization.
Global variables declaration.
USB communication initialization.
USB
connected?
One second timer
event occurred?
Insert a new point in graph and refresh the data
acquisition list.
USB data
arrived?
Data processing.
Refresh the gauge, graph and digital inputs
state.
Fig. 1. Simplified flowchart of supervisory software.
Button pushed or
scroll bar modified?
Sending USB data
Yes
No
No
Yes
No
Yes
Yes
No
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Fig. 2. Electronic design.
Page 538

Fig. 3. Simplified firmware flowchart.
Fig. 4. Bottom Copper design of PCB.
Fig. 5. Top copper design of PCB.
Start
Header files inclusion.
Fuses, delay and ports configuration.
Global variables declaration.
Configuration of the peripherals: Timers,
ADC, CCP and USB.
USB
connected?
Half second timer
event occurred?
Send the digital inputs state and the ADC
results.
USB data
arrived?
One millisecond delay.
Refresh of the PWMs duty cycles.
Refresh of the digital outputs.
Yes
No
Yes
No
No
Yes
Page 539

Fig. 6. 3D view of the PCB.
III. RESULTS AND DISCUSSION
The prototype system presented was developed and
fulfilled the desired requirements. The Fig. 7 shows the main
screen of the supervisory program. At the top of the program
there is a “file” (represented by the Portuguese word Arquivo)
menu that allows the user to connect the USB communication
and configure the data acquisition, i.e., the user can export the
data of the status of all system variables over time in a text
file or an Excel spreadsheet.
The two gauges present in the program allow the user
view the status of the analog input channels of the system.
This information is displayed in millivolts or by the result of
the analog-digital conversion performed by the 10-bit
microcontroller. It was discussed with the students the need
of adjust the range of the analog signal to 0 up 5 volts by a
signal conditioning circuit. Furthermore, according to the
transducer sensibility, a mathematical function should be
included in supervisory software for showing correctly the
measurement result. To give an example, these channels
could be used to measure the temperature of a liquid and the
pressure in a production process, using a temperature
transducer, and a pressure transducer, respectively.
Below the gauges, the user can select which of the two
analog inputs he wants to present the voltage graph, in
millivolts, over time. This type of visualization allows the
user to analyze the temporal evolution of the measured signal
and observe the dynamics of the system.
Under the title “Digital Inputs” (represented by the
Portuguese words Entradas Digitais) it is shown the states of
four digital inputs. If the symbol is black, it means that the
input is logic low, and if it is red, high logic level. These
inputs could be used to verify status changes of digital
sensors, such as buttons, limit switches, presence detectors,
among others.
Fig. 7. Main screen of the supervisory program.
Page 540

Under the title “Analog Output” (represented by the
Portuguese words Saídas Analógicas) the user can select the
duty cycle of two PWM outputs (Pulse Width Modulation).
In class, it was discussed how to convert these PWM signals
to analog outputs, indeed. To achieve this, transistor driver
and a low pass filter should be included in the system.
In the table titled "Digital Output" the user can change the
status of four digital outputs of the system. The symbol color,
red or black, indicates the state of these outputs, which
indicate whether the device is on or off, respectively. On that
way, the user can turn on or off the devices clicking over this
symbol. For example, a motor could be driven using this
digital output. However, a transistor driver and a relay
interface should be designed according to electrical
specifications of this motor.
The Fig. 8 shows a prototype of the drive device and the
computer interface developed in this work. This is a simple
and inexpensive device. On its development less than US$
25.00 were spent.
Fig. 8. Drive unit and interface device.
For two consecutive semesters this system was presented
to students of the discipline Microcontrollers Applied to
Control Engineering and Automation. The students showed
great interest in this system, because all the stages of its
development were shown in detail. This inexpensive tool
provided students to visualize concepts in practice about
Electronics, Embedded Systems, Interfacing Systems and
Computer Programming. At the end of these semesters a
course evaluation questionnaires were distributed to students,
to have a feedback of the methodology adopted (PBL) during
the course. It is noteworthy that the final works in this
discipline have produced other learning tools, tutorials,
research projects and final projects related to the major. The
Tab. 1 shows the results of a questionnaire answered by 16
students.
TABLE I. ANSWERS TO THE SURVEY
Answers A(%) B(%) C(%) D(%) E(%)
The project has
motivated me to
conclude the
engineering course.
100.0 0.00 0.00 0.00 0.00
The project is related to
the theoretical content
of the subject.
93.75 6.25 0.00 0.00 0.00
The project has
motivated me to learn
more about the subject.
100.0 0.00 0.00 0.00 0.00
I would recommend
other students to attend
this subject with this
methodology adopted.
93.75 6.25 0.00 0.00 0.00
The project contributed
to my professional
career.
75.00 18.75 6.25 0.00 0.00
Skills and knowledge
earned during the
project will contribute
to my course final
project.
62.50 6.25 25.00 0.00 6.25
A= Strongly agree, B=Agree, C=Neutral, D=Disagree, and
E=Strongly disagree
It is really necessary to highlight the importance of this
discipline in motivating students both in undergraduate
engineering program conclusion and in learning more about
the topics discussed. On both issues, 100% of students
strongly agreed on this motivational aspect that discipline
provides.
Some students made written comments about the
methodology adopted in this discipline, mainly:
1. “It was a great experience. Practices helped a lot in
preparing the final work and I learned a lot
throughout the semester. Thank you”.
2. “This methodology is very good, my learning was
greater. I had the opportunity to review, apply and
refine some concepts previously seen”.
3. “This methodology is extremely interesting and
important for the students. It is a way of teaching the
subject and explain how to solve practical problems,
which is what will happen in the workplace”.
4. “Very good! Practical learning, with real problems”.
IV. CONCLUSION
The results of this study show that a simple and low cost
SCADA system can be used in learning embedded systems
projects, USB communication, data acquisition and
supervisory systems creation. The use of this system has
motivated students in developing projects and contributed to
the development of several final projects related to the major.
REFERENCES
[1] I. J. Oleagordia, M. Barrón, J. I. San Martín, F. J. Asensio. "Active
Methodology Applied in Engineering by PBL. I-Approach."
Tecnologias Aplicadas a la Ensenanza de la Electronica (Technologies
Applied to Electronics Teaching)(TAEE), 2014 XI. IEEE, 2014.
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[2] M. Avhad, V. Divekar, H. Golatkar, S. “Microcontroller based
Automation system using Industry standard SCADA.” Annual IEEE
India Conference (INDICON), 2013.
[3] O. Krejcar. "Complete low cost SCADA system of the intelligent
house." Applied Machine Intelligence and Informatics (SAMI), 2012
IEEE 10th International Symposium on. IEEE, 2012.
[4] R. C. Hsu, W. C. Liu. "Project based learning as a pedagogical tool for
embedded system education." Information Technology: Research and
Education, 2005. ITRE 2005. 3rd International Conference on. IEEE,
2005
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LOW COST SCADA SYSTEM FOR EDUCATION

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