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A temperature monitoring system which can be used to monitor the temperature of
industrial processes has been designed and implemented in the course of this project. This
system relied upon a controller which is connected to temperature sensors. The controller
compares the actual temperature to the desired control temperature, or set point, and
provides an output to a control element. Mostly the control element is a heater. The
controller is connected to a Personal Computer (PC) using RS232 protocol, so that the
current temperature can be seen on the PC. This system offers flexibility to controlling
operations by providing a user-interface from which the temperature set-point can be
easily changed. It is believed that this project will remove rigorous and unnecessary
monitoring and controlling activities and hence ensure cheaper and faster product output.
This project has been read and approved, having met the requirements of the department
of Electronic and Computer Engineering for the award of Master of Engineering
(M.Eng.) in Electronic and Computer Engineering.
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Title page —————————————————————————————i
Certification page ——————————————————————————ii
Approval page ———————————————————————————-iii
Acknowledgement —————————————————————————–iv
Dedication —————————————————————————————v
Abstract —————————————————————————————–vi
Table of contents ——————————————————————————vii-xi
List of figures ———————————————————————————-xii-xiii
List of tables ———————————————————————————–xiv
1.1 Project background ——————————————————————-1
1.2 Aims and objectives ——————————————————————5
1.3 Significance of the study ————————————————————6
1.4 Scope of the work ——————————————————————–12
1.5 Block diagram overview of the project stages ————————————14
1.6 Project report organization ———————————————————-16
2.1 Review of works on temperature controllers ————————————19
2.1.1 Principle of operation —————————————————————-21
2.1.2 Technologies available ————————————————————–25
2.1.3 New trends —————————————————————————-27
2.2 Set-up overview ———————————————————————-30
2.2.1 Temperature measurement and sensors ——————————————-30
2.2.2 Microcontroller ———————————————————————–38
2.2.3 Serial communication –RS 232 technology ————————————–40
3.1 Methodology ————————————————————————-44
3.1.1 Structured analysis and design method ——————————————-44
3.1.2 Top-down design ——————————————————————–49
3.1.3 Bottom-up design ——————————————————————–50
3.1.4 Choice design approach ————————————————————50
3.2 Limitations of the existing system ————————————————52
4.1 System specification —————————————————————–54
4.2 Hardware subsystem design ——————————————————–55
4.2.1 Input interface ———————————————————————–55
4.2.2 The control system design ———————————————————62
4.2.3 Interfacing relay drivers to the microcontroller output port ——————66
4.3 Software subsystem design ———————————————————73
4.3.1 Program block diagram and control algorithm ———————————-73
4.3.2 Configuring the serial port of the microcontroller ——————————77
4.3.3 Configuring the PC serial port —————————————————-80
4.4 The input/output arrangement of the project ————————————-83
4.5 The project block diagram ———————————————————-84
5.1 Hardware subsystem implementation ———————————————85
5.1.1 The input interface implementation ———————————————-85
5.1.2 The control system implementation ———————————————-87
5.1.3 The output interface implementation ———————————————89
5.2 System testing ————————————————————————91
5.2.1 The test plan of the project ——————————————————–91
5.2.2 Hardware subsystem testing ——————————————————-92
5.2.3 Software subsystem testing ——————————————————–93
5.3 Performance evaluation ————————————————————-94
5.4 Project packaging ——————————————————————–94
6.1 Summary of achievement ———————————————————–95
6.2 Problems encountered and solution ————————————————95
6.3 Recommendation ———————————————————————97
6.4 Suggestions for further improvement ———————————————-99
6.5 Conclusion —————————————————————————-100
REFERENCES ——————————————————————————100-101
APPENDIX A: Full schematic diagram ————————————————–102
APPENDIX B: Software details ———————————————————-103-117
1.1 Background of the project
Cutix Plc Nnewi, a leading manufacturer of indigenous cables, produces all kinds of
cables ranging from house wiring cables to aluminum and copper conductors for high
tension installation. Cutix was founded back in 1981, and started actual production in
1984. The company has many production machines which are highly durable and rugged.
A production chart of Cutix Plc Nnewi reveals that a finished product must have passed
through the stages of wire drawing, first and second insulation, spark testing and the
finishing (coiling and sealing) line. More critical of these is the first and second
insulation stages which make use of high temperature to melt polyvinyl chloride (PVC)
materials required for coating the cables. Such situation requires a given temperature to
be kept stable to ensure smooth and uniform insulation.
Cutix, like most other manufacturing industries, makes use of analog temperature
controllers. Such controllers can accept thermocouple or RTD inputs and offer imprecise
temperature control over a range such as 75°C to 100°C. This seemed to pose no
disadvantage to them since their products still sell in the market. However, this type of
controllers used by these industry, unknowingly, possess no readable display, lack of
sophistication for more challenging control tasks, and no communication ability, all of
which most often expose the industry to the following problems:
• non-uniform heating rate for a point that requires more than one heating element, thus
causing delay in start-up of production.
• wastage of raw of materials in test-running the line to ensure that the temperature has
reached the minimum required value.
• poor package outlook because the sealers are not heated uniformly.
• extra man-power for each extrusion line- one at the take-off and another at the panel- to
ensure that the machine is stopped immediately there is a sign of poor quality due to
failure of one or more of the heaters.
• frequent damage of heating elements as a result of no precision in control which often
leads to over-heating the elements beyond upper temperature range.
Figure1.1: Production flow chart of Cutix Plc, Nnewi.
Wire drawing: diameter,
concentricity, surface checks &
annealing check (if applicable)
Cu and Al rods-diameter, tensile
strength, elongation % & resistance
Lab test 1: concentricity, diameter,
elongation%, tensile strength, resistance.
Cu & Al raw
Extrusion Line 1- Insulation:
concentricity, core diameter, spark test,
surface colour & smoothness
Lab test 2- insulation thickness, tensile
strength, enlongation voltage & flame
Laboratory test 3- Sheathing: Thickness,
tensile strength, elongation5, High
voltage and repeat of lab test 2
Coiler; Spark test, length and weight per
coil; surface colour and smoothness
Sealing and Wrapping Line: Surface
Final Inspection
Finished Goods in Store
Raw materials: PVC (resin
density), presence of pores &
moisture), PVC master batch
resin density and colour
PVC Compounding line: weight
or Hardness
1. Raw materials- wrapping sheets,
lettering and thickness.
2. labels- colour cable type& size, etc.
Fine wire
line: fine
In view of the above limitations, and more, a pc-based automatic multi-point temperature
monitoring and control is hereby proposed to remove the limitations of analog controllers
and even add flexibility to the control process.
Today, with the continuous price erosion and performance increase of pc, industrial
control is moving from an expensive, analog proprietary hardware base to one with
foundation of pc-based software. Pc-based temperature control runs on personal or
industrial hardened computers and provides answers to initiatives for lean control
With the inherent advantages of a pc-based control which include flexibility, high
performance, customization, convenience, easier development, better integration with
existing hard wares, portability and access, the proposed system should be able to help
Cutix (and other manufacturing industries) solve their problems by providing uniform
heating, precision in measurement and control, self monitoring and extension of usage to
remote, inaccessible locations in the manufacturing floor.
1.2 Aims and Objectives
This project “PC-based automatic multipoint temperature monitoring and control” is
aimed at designing a temperature monitoring and control device which can be used to
monitor and control the temperatures of industrial machines. Thus, the completed work
can be viewed as a system having three main features which serve as the objective of the
•PC-based temperature monitoring and control.
•Automation facility, which enables the system to be self monitoring.
•Multi-point approach, a feature that makes it possible for more than one point to be
Hence, this project is meant to offer flexibility to monitoring operations by allowing or
providing a PC-interfacing feature which allows an operator to monitor the ongoing
process from his PC located at amore convenient and easy-accessible place. It is believed
that this project will be able to remove the rigorous activities of monitoring temperatures
by personnel, and engage him with other production activities, all aimed at ensuring
cheaper and fast product output.
1.3 Significance of the Study
The beginning of a sweeping change is upon the control and instrumentation world with
the availability of robust hardware, open technology and real-time, window-based
operating system. PC-based control is emerging as a new control paradigm for increasing
manufacturing productivity. PC-base automatic multi-point temperature monitoring and
control offers open and more intuitive traditional solutions at a lower total system cost
and easier migration to future technologies. Easier development, integration, portability,
and access, ensure a flexible and efficient solution. Some of the inherent advantages of
PC-based automatic multipoint temperature monitoring and control include the
•Custom user-interface for supervisory control.
For low-end PID (Proportional Integral-Derivative) controllers to high end
programmable logic controllers (PLC) system, visualizing the control application can be
very challenging. Many stand-alone controllers have fixed digital displays for
configuring control set-points and viewing I/O values. PC-based automatic multipoint
temperature controller, being an advanced system, on the other hand, have no display and
typically requires a separate software package and human machine interface (HMI) to
view and interact with automation systems.
•Easy integration with existing system
One may already have a control system that works well for most needs but could benefit
from additional measurement I/O or advanced control functionality to optimize certain
specialized tasks. A big advantage to using data acquisition hardware and an open PC
platform is the number of options you have for connecting to existing equipment.
Whether you are communicating with process instrument, PLC, or single loop
controllers, you have a variety of ways to integrate a PC-based control system with
existing hardware, this is exactly what a PC-based automatic multipoint temperature
monitoring and control does in the case of temperature measurement.
•Software-defined control flexibility.
A PC-based automatic multipoint control system offers you complete flexibility in
defining system functionality and I/O operations. In addition, even without prior
technical skill in wiring a temperature controller, PC-based automatic multipoint control
system enables an operator to carry out initial installation since the system just requires
relocating it to another sight without rewiring process [5]. Also such unskilled operator
make changes in the initial setting using the window-based control interface.
•Multipoint monitoring and control for performance and reliability.
Beside single point digital temperature controllers which can control only one process,
multipoint digital temperature controllers control more than one point, meaning they can
accept more than one input variable. Generally speaking a multipoint controller can be
thought of as a device with many individual temperature controllers inside one chassis.
These are typically mounted behind the panel in some industrial applications, as opposed
to the front-to-panel (FTP) [9]. Multipoint temperature controllers provide a compact
more modular system that operates either within a stand alone system or in a PLC
environment. They provide a single point of software to access all control loops.
•Enhanced security
PC-based automatic multipoint temperature monitoring and control systems also have
enhanced security such as not having buttons for a person to use and change critical
settings. By having complete control over the information being read from or written to
the multipoint controller, the machine builder can limit the information that any given
operator can read or change, preventing undesirable conditions from occurring, such as
setting a set point too high to a range that may damage products or the machine.
Today, manufacturers around the world look to PC to play a bigger role in their control
systems. PCs are already an accepted platform for supervisory control, monitoring and
reporting, as well as off-line data management and analysis. Manufacturers have already
realized the flexibility of the PC and the easy-to-use open architecture of window-base
software applications for manufacturing environment.
Following the trend, PC-based automatic multipoint temperature monitoring and control
has emerged to facilitate efficient monitoring and control process for manufacturing
industries. Such temperature controllers are used in a wide variety of industries to
manage manufacturing processes or operations. Some common applications include the
•Heat Treat/ Oven
Temperature controllers are used in ovens and in heat treating applications within
furnace, ceramic kilns, boilers and heat exchangers.
Temperature controllers must maintain a uniform level at designated temperatures and
process time length. This helps to ensure a high quality product output.
Temperature control in the plastic industry is common on portable chillers, hoppers and
dryers, and molding and extruding equipment, temperature controllers are mused to
precisely monitor and control temperatures at different critical points in the production of
•Health care
Temperature control is required in laboratory and test equipment, autoclaves, incubators,
refrigeration equipment and crystallization growing chambers and test chambers where
specimens must be kept or test must be run within specific temperature parameters.
•Food and beverage
Common food processing applications involving temperature control include brewing,
blending, sterilization and cooking and baking ovens. Controllers regulate and/or process
time to ensure optimum performance.
•Cable manufacturing
Insulation materials require a specific temperature which must be maintained uniformly
throughout the barrel and nozzle zones to ensure good quality of product. Efficient
temperature monitoring and control systems are required to achieve this.
Finally the steps taken to incorporate PC to temperature monitoring and control is one of
the many steps required for a complete computer automation of industrial processes.
Thus other parameters, such as pressure, colour, texture and so on, can be computerized,
providing a platform for a unified process control.
1.4 Scope of the work
This work covers the following areas.
•Temperature measurement
Temperature sensors are reviewed and choice made on the most applicable sensors. The
sensor measures the temperature of the points and converts the reading to a voltage
value. This value is then sent to the microcontroller which compares it with the set-point
value, takes appropriate action in order to restore tolerable limits.
•Hardware programming.
High level C-programming language is used to develop codes for the microcontroller to
enable it read the values sent by the sensors and take appropriate actions. The Visual
Basic Window-based software will be used to communicate with the PC operating
system and the C program running on the hardware in order to read the user set-point
values and current temperatures.
•Window-based software programming.
Communication between the hardware and the PC (serial communication) is facilitated
by programming the PC to be able to communicate with the serial port. The Visual Basic
Window-based software will be used to communicate with the PC operating system and
the C program running on the hardware in order to read the user set-point values and
current temperatures.
•Level conversion
In order to ensure a compatible voltage level between the hardware and the PC, the MAX
232 technology is employed. This converts the hardware voltage level to a voltage which
can be handled by the serial port in the PC.
1.5 Block Diagram Overview Of the Project Stages
Fig1.2 Block diagram of a pc-based temperature controller
A temperature control system relies upon a controller, which is connected to a
temperature sensor. It compares the actual temperature to the desired control
temperature, or set point, and provides an output to a control element. Mostly the control
element is a heater. The controller is connected to a Personal Computer using RS232
protocol. The Current Temperature can be seen on the PC. Whereas the Temperature Set
Point can also be changed through the PC. The different sections of this project are:
1. Microcontroller.
2. Analog to Digital Converter (ADC).
3. Temperature Sensor.
4. Relay.
5. MAX 232.
It is the heart of the unit. It performs all the functions like getting data from ADC,
Comparing the current temperature to set temperature, Turning ON/OFF the relay &
communicating with the PC.
Analog to Digital Converter
The ADC Converts the Analog voltage received from the Temperature Sensor into
digital format and gives it to the microcontroller.
Temperature Sensor
The temperature sensor measures the current temperature and sends value in form of
voltage to the microcontroller. Some IC (e.g. LM35) sensors have output proportional to
the input temperatures.
Communication with the PC is done through the SERIAL PORT. The protocol of serial
port is RS-232, for interfacing the controller to the PC using RS 232 protocol we require
MAX 232 IC.
1.6 Project Report Organization
The design and implementation of the project, PC-based automatic multipoint
temperature monitoring and control system, followed a systematic approach which
reveals a step by step analysis of an existing system, taking Cutix Plc Nnewi as a case
study, until a realizable, better system is arrived at. This report covers the entire steps
followed to arrive at the complete envisaged system. Diagrams and tables are employed,
where necessary, to illustrate facts and results.
Chapter one of this report is an introduction to the project. It covers the following areas:
the project background, aims and objectives of the work, justification and scope of the
work, and the block diagram overview of the project stages.
Chapter two is a literature review of related works. In this chapter, the general concept of
temperature control is x-rayed; different technologies of relevant components are also
In third chapter, the temperature control technique as used by Cutix Plc Nnewi is
analyzed and shortcomings of the existing system outlined. Different methods of
achieving a better system are also explored. Then, choice is made among all the available
options. The option chosen is basically dependent on the nature of the envisaged system.
Chapter four describes the proper system design. The input, output and software
interfaces are systematically modularized and designed. The block diagram of the
modules (put together) is also given towards the end of this chapter.
The whole of chapter five is concerned with the implementation of the designed system.
This involves the wiring schedules, full schematic diagram and integration of the
different modular designs and schematics, testing and performance evaluation, costing
and deployment of the achieved work.
Finally, the last chapter deals with the summary of achievement, problems encountered
during the project design and implementation stages and the solution proffered.
Recommendations and suggestions for further improvement are also included.


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