Implementing IoT Technology in Practice:

Monitoring the Supply Chain for Sustainable Operation

CHRISTOS PECHLIVANIS

Sector of Industrial Management and Operational Research, School of Mechanical Engineering,

National Technical University of Athens,

9, Iroon Polytechniou str., 15772, Zografou, Attica,

GREECE

Abstract: The Internet of Things (IoT) is proliferating, with thousands of new sensors and equipment going live

each month. Despite its lengthy evolution, the Internet of Things has only recently begun to take off in the mass

market due to low-cost, reduced-power elements, ubiquitous web access, and high business and consumer

interest. The Internet of Things includes anything from intelligent kitchen appliances to smart buildings, smart

lighting on streets to automated manufacturing processes, and adaptive home heaters to autonomous vehicles.

This research concerns studying and applying Internet of Things (IoT) technology to monitor the supply chain

and achieve more sustainable operations by ensuring accurate and real-time data monitoring. In this context, an

experimental device is developed to read the values of selected physical quantities from the wine supply chain

environment through appropriate sensors. The values are then sent to an IoT platform to facilitate the remote

monitoring of the above physical quantities and extract valuable insights from the large volume of data

generated. The results show that crucial information can be gathered in real-time, enabling quick decision-

making and ensuring safer and more sustainable supply chain operations.

Key-Words: Internet of Things; Supply Chain; Sensors; Real-time Monitoring; Sustainability

Received: July 9, 2022. Revised: March 1, 2023. Accepted: March 17, 2023. Published: March 24, 2023.

1 Introduction

The Internet of Things (IoT) is a system of linked

devices, electronic and mechanical machines, items,

and living beings, that have unique identifiers

(Unique Identifiers – UIDs) and can transfer

information through a network without the

requirement of human-to-human or human-to-

computer interaction. A thing in the internet of

things could be a human wearing a smartwatch, a

farm animal with a micro / nano transmitter, a

vehicle with integrated sensing devices that alert

people when gas leakage is detected, or any other

organic or artificial entity that can be appointed an

Internet Protocol (IP) identifier and can transfer data

over a network [1–3].

IoT enables individuals to live and work more

efficiently and acquire total control over their life.

IoT is vital for companies in addition to providing

mobile smart devices for operation automation [4].

IoT enables organizations to monitor their systems'

performance in real-time, delivering data on

anything from machine performance to supply chain

and logistics procedures[5]. The Internet of Things

allows companies to streamline operations and cut

personnel expenses. In addition, it lowers waste and

enhances service delivery, reducing the cost of

production and delivery of goods and enhancing the

transparency of consumer interactions.

Consequently, IoT has become an essential

technology and will keep growing as increasing

numbers of organizations see the possibilities of

interconnected devices to enable them to survive

and thrive[6].

The IoT network is rapidly expanding, with

countless new devices and sensors coming into play

each month. Despite its relatively long track record,

the Network of Things is only now commencing to

take off due to the availability of low-cost, low

energy needing solutions, extensive network access,

and the high level of business and consumer interest

[7, 8]. The Internet of Things includes anything

from intelligent kitchen appliances to smart

buildings, tracking devices in distribution networks

to healthcare monitoring devices, and adaptive

heaters to self-driven vehicles [9, 10].

Today, more than ever, developing IoT

applications is becoming more cost-effective,

simpler, and much more generally accepted than

ever before, resulting in modest waves of

advancement throughout the market. IoT is

advancing as an intriguing premise for the coming

years. This can be seen in today's applications, such

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as automated vehicles and smart homes, which are

constantly becoming more effective and accessible

[11, 12]. The retail industry and the supply chain

generally have a considerable potential to become

more intelligent. Proximity advertising through

Beacons and innovative inventory management

technologies used in stores with no cash registers

are prime examples [6,13]. However, IoT devices

and apps in retail usage extends beyond the buying

experience. It allows hotel, food, and

beverage service providers and other companies to

monitor their resources and gather valuable data.

This can give merchants complete control over their

supply chain operations by automating many

manually performed actions. [14]. Thus, business

owners can avoid placing large orders, effectively

limit staff members who abuse their privileges and

manage logistics and trade costs more efficiently.

The above benefits, in turn, lead to high adoption

rates of all IoT products along the supply chain [15].

The benefits of IoT in supply chain management are

summarized as follows [16–18]:

 enhanced supply chain transparency

 automated check-in and check-out of goods

 monitoring the location of the goods and the

storage conditions in the warehouse

 preventive maintenance of the equipment

 inventory management and theft prevention

 improving the shopping experience and customer

service

 detection and early notification of any problems

during transport

 warehouse demand notification

 route optimization

This research builds on the massive potential of the

supply chain sector and presents an application of

Internet of Things (IoT) technology to monitor the

supply chain and achieve more sustainable

operations by ensuring accurate and real-time data

monitoring. To achieve this goal, it is necessary to

use a few critical parts of an Internet of Things

application, such as Sensors and Deployment

Boards, for reading the potential of physical

quantities, converting them into electrical

potential/voltage, translating them into data,

processing and sending them, and IoT Platforms,

which allow the end user to monitor the desired

variable within the supply chain. This research

differs from most existing ones by connecting

theory with practice as it has a theoretical

contribution and presents a working IoT application

developed to demonstrate a simple, flexible and

cost-effective solution for more sustainable supply

chain operations.

In the remainder of the paper, in section 2, the

architecture of the Internet of Things is analyzed,

including the necessary components and some

information on how each layer works. Section 3

presents the basic parts that make up a typical

Internet of Things application. More specifically,

this section provides information on the sensors,

actuators, development boards and IoT platforms

necessary to develop any IoT application. Finally,

section 4 concerns the case study of the research and

includes a description of the parts that make up the

developed experimental setup, as well as the way of

its implementation, i.e., the circuit and the codes

that were created for connecting devices and

communicating. Finally, the developed dashboard is

presented through which users can monitor, in real-

time, the values of the selected physical quantities.

2 ΙοΤ Architecture & Characteristics

As seen in Figure 1, an IoT ecosystem includes

internet-enabled, smart devices that employ

intelligent systems such as processing units, sensors,

and devices that communicate to collect, transmit,

and act on environmental data. IoT devices

exchange the sensor data they acquire by connecting

to an IoT Gateway, from which the information is

either transferred to the Web or processed in a local

environment. Occasionally, these devices connect

with other interconnected smart objects and act in

response to the data they receive [19]. Most tasks

are performed by equipment without interaction

between people; however, individuals can engage

with these devices to make them work, provide

them with directions, or monitor the information.

These web devices' connection, infrastructure, and

protocols significantly rely on the deployed IoT

applications. IoT may also utilize artificial

intelligence (AI) and machine learning (ML)

technology to make data-collecting procedures more

dynamic and efficient [20].

Fig. 1: IoT Ecosystem

Established decades ago, the Transmission Control

Protocol (TCP) / IP protocol stack is currently used

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by the World wide web to interact among nodes.

Nevertheless, the Internet of Things links thousands

of items, increasing bandwidth and necessitating

significantly greater storage space. Moreover, IoT

confronts several privacy and security

difficulties[19]. Thus, the newly suggested Internet

of Things (IoT) infrastructure must handle various

elements, such as scaling, interoperability,

dependability, service quality, etc. [20]. Considering

IoT links each and every individual in order for

them to exchange information, internet traffic and

data transfer will expand dramatically. Therefore,

the growth of IoT depends on technological

progress and the creation of new applications and

economic models. The fundamental IoT architecture

consists of five levels, as seen in Figure 2.

Fig. 2: Basic IoT Architecture

This basic IoT architecture consists of five main

layers [21]:

1. Perception Layer: This is also referred to as the

"device layer". Material entities and sensing

devices constitute its composition. Depending on

the manner of object detection, the sensors may

be RFID, 2D-barcode, or infrared sensors. This

layer is primarily focused on the recognition and

information gathering of entities via sensing

devices. Depending on the kind of devices, the

information may be associated with a plethora of

physical aspects. The gathered information is

subsequently sent to the network layer for safe

transmission to the data processor.

2. Network Layer: This is often referred to as the

transport layer. This layer transmits the

information collected by the sensing devices to

the data processor securely. The communication

method may be cable or wirelessly, depending on

the sensing devices. Consequently, the network

layer sends data from the perception layer to the

middleware layer.

3. Middleware Layer: This layer oversees managing

IoT services and database connections. This layer

gathers information from the network layer and

stores it in a repository. It analyses the input,

performs omnipresent computations, and makes

choices automatically based on the outcomes.

4. Application Layer: This layer enables global

application administration based on item

information processed in the middleware layer.

Applications of IoT have a vast variety and may

include smart buildings and cities, smart

cultivations, smart supply chains, etc.

5. Business Layer: This layer is accountable for

controlling the IoT ecosystem, encompassing

apps and data. It develops business strategies and

models using information collected from the

application layer, including graphs, diagrams,

etc. The true success of an IoT ecosystem also

depends on effective business strategies, and this

level helps determine subsequent decisions and

business strategies based on examining the

outcomes.

3 Components of an IoT Application

The world of the Internet of Things (IoT) continues

to grow and evolve rapidly, effectively framing the

capabilities of the cloud. Broadly speaking, IoT is a

network of physical objects that exchange data over

the internet. Every advancement in the IoT market

leads to an increase in businesses benefiting from

the technology, which is becoming more and more

advanced over time. The benefits of IoT cannot be

ignored, with its use in sectors ranging from home

automation and agriculture to medicine and supply

chains. Technology has the potential to assist

different businesses with multifaceted requirements

[22, 23]. This section presents the main components

necessary for developing any IoT application.

Sensors are the leading component, and today,

more than ever, are used in a plethora of industrial

operations. Industrial enterprises and organizations

have been using various kinds of sensors, but the

invention of the Internet of Things has taken the

evolution of sensors to a whole different level. IoT

platforms operate and deliver various types of

intelligence and data using a wide range of sensors.

They serve to collect data and send and share it

across a whole network of connected devices. All

this collected data allows devices to operate

autonomously, and the entire ecosystem is

becoming increasingly "intelligent" every day [24].

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By combining a set of sensors and a

communication network, devices share information

with each other and improve their efficiency and

functionality. For example, Tesla vehicles. All the

sensors in a car record the information they receive

from the environment, which they upload to a vast

database. The data is then processed, and all

important new information is sent to all other

vehicles. It is an ongoing process through which an

entire fleet of Tesla vehicles becomes smarter every

day [25, 26]. The primary sensors used in industrial

IoT applications are for receiving data and

monitoring the following physical aspects:

1. Temperature

2. Proximity

3. Pressure

4. Water Quality

5. Chemical Properties

6. Gas

7. Smoke

8. Infrared Rays

9. Fluid Level

10. Image Transformation

11. Motion Detection

12. Acceleration

13. Gyroscope

14. Humidity

15. Optical Rays

Another critical component is the actuators. In IoT,

actuators provide the ability to perform a physical

action or movement based on data coming from one

or more sensors. The transformation of the data

collected by the sensors into action follows the

following sequence [27]:

 Sensors that detect sense a change occurring in the

natural world.

 Sensors turn event-related data into electrical

impulses sent to a controlling device, whose

system calculates when and what action is

required.

 The controlling device commands the actuator to

execute the needed motion.

 The actuator performs its function by transforming

electricity into real action.

For instance, an Internet of Things application that

controls a fridge contains sensing devices that read

its temperatures. As designed, the sensors provide

heat information to the management unit. The

control mechanism checks these measured data

compared to the preset ideal temperature range. If

the data is above or below this spectrum, the

management system transmits an order to an

actuator to activate or deactivate the fans. In several

IoT solutions, the sensor, controller, and actuator are

distinct physical components that connect through

wireless or cabled networking and a Web service. In

other instances, these three components are

incorporated into a single physical device. A basic

definition of an actuator is a mechanism that

converts power into activity or movement [28, 29].

As the IoT ecosystem grows, so does the need for

IoT development boards, which can be used for both

testing and mass production. A development board

is only a component that connects containing

electrical circuits and hardware intended to facilitate

experimentation with a specific microcontroller. IoT

developers mostly utilize them to construct trials

before launching the finished versions. There are

three classes of IoT boards [30, 31]:

1. Microcontroller-based boards: These boards

include a miniature computer built on a metal

oxide semiconductor circuit chip.

2. System-on-chip (SoC) boards: An SoC board

incorporates all the required electrical parts and

circuit system components on a single Si chip.

3. Single Board Computers (SBC): A SBC is a

computer constructed entirely on a single printed

circuit board. It contains all functional computer

components and is mainly used for

demonstrating purposes.

IoT platforms are the last component essential for

every IoT solution. The Internet of Things (IoT)

platform industry is expanding, with the value of the

worldwide IoT market anticipated to reach $1.1

trillion by 2026 [32]. This significant growth in

demand for IoT applications is due to the rise of IoT

solutions and other associated components. IoT

sensors and many connected components need a

coordinator - IoT platforms - to collaborate and

operate smoothly within the same ecosystem and

provide the highest potential competitive

advantages. IoT platforms are middleware systems

that link IoT solutions to the cloud and enable

smooth data interchange across the network. They

serve as intermediaries between the application

layer and the hardware resources. There are

currently several IoT platform suppliers on the

marketplace and every one of them has its unique

method for simplifying and scalability IoT

integration and administration [33].

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4 Case Study: Developing an IoT

Application for the Wine Supply

Chain

It was decided to select the wine supply chain as a

case study for developing an IoT application. This

specific supply chain needs significant

improvements for traceability and protection against

counterfeit activities as it is highly vulnerable.

Moreover, ineffective traceability may lead not only

to economic losses but also to severe health risks as

wines are found to be frequently adulterated. In the

present case study, it was decided to monitor the

temperature and humidity conditions of wines to

ensure that no quality deterioration exists during the

aging process of the wines. However, to effectively

combat counterfeit activities, many more physical

aspects would be required to be monitored.

Figure 3 presents the selected IoT components as

they were analyzed in section 3.

Fig. 3: Selected IoT Components for the Case Study

A Digital-output, relative Humidity, and

Temperature (DHT11) sensor monitors the

temperature and humidity prevailing inside the

storage area. There are many different versions of

this sensor. In the present work, a sensor of this type

with four pins was used. The DHT11 is a relative

humidity meter. The definition of relative humidity

is the ratio of the quantity of water vapor in the air

to its saturation point. At the saturation point, water

vapor condenses and collects on surfaces,

generating dew. The saturation point varies with air

temperature. Cool air can trap less water vapor

before saturation occurs, unlike warm air which has

a higher saturation point. The relative humidity is

expressed as a percentage. In other words,

condensation occurs when we have 100% relative

humidity, while when we have 0% relative

humidity, the air is completely dry.

The DHT11 measures the electrical resistance

between two electrodes to detect water vapor. The

moisture sensing device is a moisture-retentive

substrate with surface-mounted electrodes. When

the substrate absorbs water vapor, ions are

discharged from its surface, increasing the

conductivity between the electrodes. The ratio of the

change in resistance between the two electrodes to

the relative humidity is proportionate. Lower

relative humidity raises the resistance between the

electrodes, while higher relative humidity reduces

the resistance. The DHT11 uses a Negative

Temperature Coefficient (NTC) temperature sensor

to monitor temperature (thermistor). Thermistors are

a type of resistor whose value is affected by

temperature much more than ordinary resistors. The

thermistor used in the DHT 11 is NTC, which

means that the resistance decreases with increasing

temperature.

Using jumper cables and a breadboard, the

DHT11 sensor is connected to the Raspberry Pi

through the General-Purpose Input/Output (GPIO)

pins. Specifically, pin 2 is a serial data (SDA) pin

used for data transfer and is connected to GPIO 17,

pin 1 is a Voltage Common Collector (VCC) pin

related to power and is connected to GPIO 3V3

power, which provides an output voltage of 3.3V,

pin 4 is a Ground (GDN) pin connected to GPIO

Ground, while pin 3 is Not Connected (NC)

somewhere as it has no functional purpose for the

external circuit. To get the data from the sensor, the

dht11.py library was used which is imported at the

beginning of the code. First, the numbering method

that will be used to determine the GPIO pins

through which communication takes place between

the sensor and the Raspberry Pi, specifically GPIO

17, is determined. In this particular case, the

Broadcom (BCM) numbering method GPIO.BCM is

used where the various GPIO pins are identified by

their number, i.e., for GPIO 17 we simply write 17.

Another way of numbering is GPIO.BOARD in

which the identification of GPIO pins is done by

writing the number of the position as they are

physically arranged with the numbering starting

from 1 and reaching up to 40. Then, using the

dht11.py library, we construct an object of the

DHT11 class inside the above library. Creating the

above object requires determining the GPIO pin to

which SDA pin 2 of the sensor is connected.

Finally, it is possible to read the temperature and

humidity values through the read method.

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Raspberry Pi 4 Model B was used as a development

board in this work. Raspberry is a credit card-sized

computer developed by the Raspberry Pi Foundation

in Great Britain and first sold in 2012. Although

initially promoted as a means of teaching computer

science in developing countries, it has also seen

great commercial success in other areas, such as

robotics. This has led to the release of several

versions, including improvements over previous

versions in terms of computing power, using a faster

processor and more RAM, as well as Raspberry

connectivity, with Wi-Fi and Bluetooth integration,

without the need to add an external adapter.

Finally, Ubidots was used as a development

platform. Ubidots is a platform that supports the

development of IoT applications. It enables the user

to record, monitor, and manage in real-time the data

collected by the sensors through any networking

technology, and turn it into useful information. In

addition, it allows configuring actions and alerts

based on the state of the system as determined

through sensor readings. It also offers powerful data

visualization tools, some of which were utilized in

the current implementation. Finally, the platform is

available in two versions. The first is for personal or

academic use and is complimentary, while the

second, which comes with more features, is for

businesses and requires paying fees. The

complimentary version of the Ubidots platform,

Ubidots STEM, was used in the current work.

To transfer the data from the sensor through the

Raspberry Pi to the Ubidots platform, the MQTT

communication protocol was used, which is a

publish-subscribe protocol as opposed to the more

widespread HTTP communication protocol, which

is of the get-request type. This protocol consists of

three entities, the publisher, the subscriber, and the

broker. Communication using this protocol is done

through topics. Specifically, the publisher publishes

some values on a topic. On the other hand, the

subscriber subscribes to a topic to be informed about

its prices. Finally, the broker manages all the

publications in the various topics from the

publishers and then informs the subscribers in each

topic about the new prices.

To connect the Raspberry Pi to the Ubidots

platform through the MQTT communication

protocol, we first created a device on the Ubidots

platform named "raspberrypi". Then we created two

variables in this virtual device, one with the name

"temperature" and one with the name "humidity". In

this way, we created the necessary topics in which

the Raspberry Pi will publish the new temperature

and humidity values that the sensor reads. Finally,

The UbidotsIoTDevice class was developed as a

wrapper of the "paho – mqtt" library, which enables

connection to an MQTT broker to publish and

receive messages by subscribing to topics using the

MQTT communication protocol. The above class

aims to hide, as much as possible, the complexity

involved in the process of creating code to establish

communication between an internet-enabled

computing device and the Ubidots STEM platform

from the user-programmer. The body of the

UbidotsIoTDevice class is listed in Appendix A.

Figure 4 presents the physical circuit as it was

developed. In addition to the sensor and the

Raspberry Pi, together with its GPIO Extension

Board to avoid damage to the GPIO pins, a

breadboard and jumper wires were used to

implement the circuit.

Fig. 4: The Physical IoT Circuit

A breadboard is a board used to make temporary

circuits. It has multiple holes in horizontal or

vertical groups that share the same potential through

metal cables that connect them and are under the

plastic cover. The great advantage of this board is

that it offers a quick, direct, and non-permanent way

of connecting and disconnecting electronic

components to each other without any risk of

damaging them, provided that the various

components are handled with the required care. This

makes it the most efficient way to test circuits.

As far as jumper wires are concerned, they are

simple cables with the appropriate configuration at

their ends, either pins or recesses, thus allowing the

possibility of connecting two points without

welding. They are usually used together with a

breadboard to change the wiring of a circuit directly.

There are three types of jumper wires: Male to

Male, Male to Female, and Female to Female. The

difference is that the male termination corresponds

to a pin, while the female termination corresponds

to a socket (each cable has two terminations).

Additionally, an appropriate code was

developed in the PYTHON programming language

to read the temperature and humidity values from

the Raspberry Pi 4 Model B development board

through the DHT11 temperature and humidity

sensor. This code is also used for sending the values

from the Raspberry Pi 4 Model B development

board to Ubidots STEM platform using the

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UbidotsIoTDevice class. This code is presented in

Appendix B.

Finally, to create the interface through which

the user will be able to monitor the temperature and

humidity values in real-time during the transfer

stage, the tools offered by the Ubidots STEM

platform environment were used. The interface is

shown in Figure 5. On the left, in the two widgets,

the user can read the temperature and humidity

values in real-time, while on the right, in the two

graphs, they can monitor the evolution of these

values over the last 24 hours.

Fig. 5: Dashboard for Monitoring Temperature and

Humidity Values

5 Conclusion

It has been predicted that the demand for IoT

technology will grow much faster to cover billions

or even trillions of wireless devices and sensors in

the coming years. However, this increase will

depend to some extent on the ability of

manufacturers to reduce the cost of IoT devices

while also meeting all users' needs. The developed

IoT application attempted to present a cost-effective

solution for measuring temperature and humidity in

the wine supply chain. The application uses a

DHT11 sensor that measures temperature and

humidity. The sensor is connected to the Raspberry

Pi 4 Model B development board using a GPIO

Extension Board, a breadboard, and jumper wires.

The development board connects to the Ubidots

platform through the developed UbidotsIoTDevice

class. Finally, the appropriate PYTHON code

enables reading temperature and humidity data from

the sensor. The IoT application was tested in a lab

environment and both the temperature and humidity

data were confirmed to be highly accurate.

The developed application is a simple, flexible,

and cost-effective method to monitor temperature

and humidity in the wine supply chain. Applying

such solutions in business operations presents a

massive opportunity to build a sustainable and

prosperous future. IoT technology may help

organizations reduce their environmental effect,

adjust to a new context, and increase their

production and effectiveness. Notably, in the supply

chain, IoT technology can significantly reduce the

carbon footprint of activities and lead to a more

efficient use of available resources.

The application proposed in this work can be

used, with some additions and improvements,

throughout the supply chain, even in crops or fields,

to monitor soil temperature and humidity. To install

the device in an outdoor environment, it is necessary

to place it in a waterproof housing and to be

powered by a rechargeable battery, possibly

connected to a photovoltaic panel, so that charging

is done automatically. It can also be expanded so

that, in addition to the monitoring part, it also

implements automation, such as the automatic

notification of companies when the temperature and

humidity levels go beyond the permissible limits. In

fact, the notification can be made in real-time so that

the necessary measures are taken immediately, and

the quality of the products is not altered.

In addition, the application can be enriched

relatively quickly with a variety of other suitable

sensors to enable efficient monitoring of the entire

supply chain. Examples of sensors that could be

used are motion sensors to detect attempted

sabotage, chemical sensors to detect changes in the

quality of wine, fluid level sensors to detect

attempts to dilute wine, accelerometers, and

gyroscopes to detect unwanted movements and even

location devices to monitor the wine transportation.

Therefore, as it becomes clear, IoT technology

presents a massive potential for more accurate, safe

and sustainable supply chain operations.

6 Appendix A: UbidotsIoTDevice

Class

---Start of Code---

import paho.mqtt.client as mqtt

import socket

import time

# Ubidots

HOST = "things.ubidots.com"

PORT = 1883

TOPIC = "/v1.6/devices/"

class UbidotsIoTDevice:

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def __init__(self, device_token: str,

device_label: str, *variables_to_subscribe:

str):

self.__connected = False

self.__subscribed = False

self.__published = False

self.__reconnected = -1

self.__device_token = device_token.strip()

self.__device_label =

device_label.strip().lower()

self.__variables = dict()

for variable in variables_to_subscribe:

self.__variables[variable.strip().lower()] = -1

self.__client = self.__create_mqtt_client()

self.__create_subscriptions()

def __del__(self):

self.__client.loop_stop()

self.__client.disconnect()

def __on_connect(self, client, userdata, flags, rc):

if rc == 0:

self.__connected = True

self.__reconnected += 1

if self.__reconnected:

self.__create_subscriptions()

def __on_subscribe(self, client, userdata, mid,

granted_qos):

self.__subscribed = True

def __on_publish(self, client, userdata, mid):

self.__published = True

def __create_mqtt_client(self):

client = mqtt.Client()

client.username_pw_set(username=self.__devi

ce_token, password="")

client.on_connect = self.__on_connect

client.on_subscribe = self.__on_subscribe

client.on_publish = self.__on_publish

while not self.__connected:

try:

client.connect(host=HOST, port=PORT)

client.loop_start()

time.sleep(1)

except socket.gaierror:

pass

return client

def __create_subscriptions(self):

for variable in self.__variables.keys():

callback = self.__create_callback(variable)

self.__client.message_callback_add(TOPIC

+ self.__device_label + "/" + variable +

"/lv", callback)

while not self.__subscribed:

self.__client.subscribe(TOPIC + self.__device_label

+ "/" + variable + "/lv", qos=1)

time.sleep(1)

self.__subscribed = False

def __create_callback(self, variable):

def on_message(client, userdata, message):

self.__variables[variable] =

float(message.payload.decode("utf-8"))

return on_message

def read(self, variable: str):

return self.__variables[variable.strip().lower()]

def write(self, variable: str, value):

while not self.__published:

self.__client.publish(TOPIC +

self.__device_label + "/" +

variable.strip().lower(), value, qos=1)

time.sleep(1)

self.__published = False

---End of Code---

7 Appendix B: PYTHON Code for

Data Gathered from the Raspberry Pi

4 Model B

---Start of Code---

# modules

import RPi.GPIO as GPIO

import dht11

import time

from Ubidots_IoT_Device import

UbidotsIoTDevice

# numbering scheme

GPIO.setmode(GPIO.BCM)

WSEAS TRANSACTIONS on SYSTEMS

DOI: 10.37394/23202.2023.22.38

Christos Pechlivanis

E-ISSN: 2224-2678

356

Volume 22, 2023

# pins

dhtPin = 17

# sensors

myDHT = dht11.DHT11(dhtPin)

# globals

delay = 10

# Ubidots IoT Devices

raspberrypi = UbidotsIoTDevice("BBFF-

iGovTvMQDrbISlaUE5KkEs6qyZhTcJ",

"raspberrypi")

# main

while True:

result = myDHT.read()

if result.is_valid():

raspberrypi.write("temperature",

result.temperature)

raspberrypi.write("humidity", result.humidity)

time.sleep(delay)

---End of Code---

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Contribution of Individual Authors to the

Creation of a Scientific Article (Ghostwriting

Policy)

Christos Pechlivanis carried out the

conceptualization, formal analysis, investigation,

project administration, supervision, validation, data

curation, methodology, resources, software,

visualization, writing of the original draft, and

review and editing of the paper.

Sources of Funding for Research Presented in a

Scientific Article or Scientific Article Itself

The author declare no funding sources.

Conflict of Interest

The authorshas no conflict of interest to declare

that is relevant to the content of this article.

Creative Commons Attribution License 4.0

(Attribution 4.0 International, CC BY 4.0)

This article is published under the terms of the

Creative Commons Attribution License 4.0

https://creativecommons.org/licenses/by/4.0/deed.en

_US

WSEAS TRANSACTIONS on SYSTEMS

DOI: 10.37394/23202.2023.22.38

Christos Pechlivanis

E-ISSN: 2224-2678

359

Volume 22, 2023