Project report on design and fabrication of temperature measurement setup

DESIGN AND FABRICATION OF TEMPERATURE

MEASUREMENT SET UP

A PROJECT REPORT
Submitted by
ARUN KUMAR.S (105914144005)
RAJESH KUMAR.M (105914144039)
RAJSHEKAR.S (105914144040)
SEENIVASAGAN.R (105914144047)

In partial fulfillment for the award of the degree of
BACHELOR OF ENGINEERING
IN
MECHANICAL ENGINEERING

RAJA COLLEGE OF ENGINEERING AND
TECHNOLOGY, MADURAI
ANNA UNIVERSITY: CHENNAI 600 025
APRIL 2013

ANNA UNIVERSITY: CHENNAI 600 025
BONAFIDE CERTIFICATE
Certified that this project report "DESIGN AND FABRICATION OF TEMPERATURE MEASUREMENT
SETUP" is the bonafide work of "ARUN KUMAR.S (105914144005), RAJESH KUMAR.M (105914144039),
RAJSHEKAR.S (105914144040), and SEENIVASAGAN.R (105914144046)" who carried out the project

work under my supervision.

SIGNATURE
Prof. P.SUGUMARAN M.E., Ph.d
HEAD OF THE DEPARTMENT

SIGNATURE
T.KATHIRAVAN B.E
SUPERVISOR
Assistant professor

Mechanical Engineering

Mechanical Engineering

Raja College of Engg&Tech,

Raja College of Engg &Tech,

Madurai- 625020.

Madurai- 625020.

Submitted for the project vice-voce held on ……………

INTERNAL EXAMINER

EXTERNAL EXAMINER

ACKNOWLEDGEMENT
This project has been successfully completed owing comprehensive endurance of many distinguished
persons.
First and foremost we would like to thank the almighty, our family members , and friends for
encouraging us to do this project.

2

We extend our heartfelt thanks to our beloved Chairman PDG.Lion. G. Nagarajan , M.A and our Principal
Dr. S.M. Sekkilar, M.E., Ph.D for their advice and ethics inculcated during the entire period of our study
We are extremely indebted to Prof. P. Sugumaran, B.E. (Distn), M.E., Ph.D, The Head Of Department of
Mechanical Engineering for the devoted attention, love and affection shown on us in making this project
grand success.
We profusely thank our internal guide, Mr. T. Kathiravan, B.E., Asst. professor, Mechanical Engineering
for his support throughout the project. His suggestions and participative encouragement throughout the
project will ever hold a memorable place in our hearts.
Finally, we thank one and all for their valuable support in this project work.

ABSTRACT
This can be used for measuring, controlling and acquisition of the temperatures
in the engineering systems. The apparatus is used mainly to observe the source temperature by
sensor and to generate graph between temperature and time by using the program in the
microcontroller. Graphs can be drawn between a temperature and time.

3

TABLE OF CONTENTS

CHAPTER NO

TITLE

PAGE NO.

ABSTRACT
LIST OF TABLES

7

LIST OF FIGURES

1.

4

8

INTRODUCTION

9

4

1.1 Temperature

10

1.2 Temperature control

SENSOR

11

2.1 Sensor

12

2.2 Sensor deviation

2.

10

12

2.3 Resistance thermometer

13

2.4 R Vs T relationship of various metals

13

2.5 Element types

15

2.6 Function

15

2.7 Advantages and limitations

16

2.8 Sources of error

17

2.9 RTDs vs thermocouples

17

2.10 Construction

17

2.11 Classifications of RTDs

18

2.12 Applications

18

2.13 History

19

2.14 Pt100 Platinum Resistance Thermometers
3.

TEMPERATURE READER (CONTROLLER)

23

3.1 Introduction to Temperature Controllers
3.2 Different Types of Controllers, and How Do They Work?

5

19

24
24

3.3 SELEC TC303
4.

26

PIC16F877A and RS232
4.1 PIC16F877A

30

4.2 RS232

5.

29

31

GRAPHICAL DISPLAY

37
5.1 Graphical LCD 128*64

38

5.2 Interfacing of PIC16F877A with 128x64 graphical display

6.

PROCEDURE

41

6.1 PROCEDURE

42

COST ESTIMATION

42

CONCLUSION

43

LIST OF TABLES
TABLE 4.1.1

38

PAGE NO

FEATURES OF PIC16F877A

31

TABLE 4.2.1

SIGNALS IN RS232

33

TABLE 4.2.2

PIN ASSIGNMENTS

34
6

LIST OF FIGURES
FIG 2.10.1

CONSTRUCTION OF RTD

FIG 2.14.1

Pt100 SENSOR

FIG 3.2.1

PAGE NO
18

STANDARD PANEL SIZES

20
26

7

FIG 3.3.1


FIG 4.1.1

PIC16F877A

FIG 4.2.1

RS232 cable

FIG 5.1.1

28
31

36

Graphical LCD 128*64

38
FIG5.2.1
FIG 6.1

Interfacing of PIC16F877A with 128x64 graphical display

40

BLOCK DIAGRAM OF TEMPERATURE MEASUREMENT SETUP 42

CHAPTER1

8

INTRODUCTION

1.1 Temperature:
Temperature is a physical quantity that is a measure of hotness and coldness on a numerical scale. It is a
measure of the thermal energy per particle of matter or radiation; it is measured by a thermometer,
which may be calibrated in any of various temperature scales: Celsius, Fahrenheit, Kelvin, etc.
Temperature is an intensive property, which means it is independent of the amount of material present;
in contrast to energy, an extensive property, which is proportional to the amount of material in the
9

system. For example a spark may well be (very briefly!) as hot as the Sun.
Empirically it is found that an isolated system, one that exchanges no energy or material with its
environment, tends to a spatially uniform temperature as time passes. When a path permeable only to
heat is open between two bodies, energy always transfers spontaneously as heat from a hotter body to
a colder one. The transfer rate depends on the thermal conductivity of the path or boundary between
them. Between two bodies with the same temperature no heat flows. These bodies are said to be in
thermal equilibrium.
In kinetic theory and in statistical mechanics, temperature is the effect of the thermal energy arising
from the motion of microscopic particles such as atoms, molecules and photons. The relation is
proportional as given by the Boltzmann constant.
1.2 Temperature control:
Temperature control is a process in which change of temperature of a space (and objects collectively
there within) is measured or otherwise detected, and the passage of heat energy into or out of the
space is adjusted to achieve a desired average temperature.

CHAPTER 2

10

SENSOR

2.1 SENSOR:
A sensor (also called detector) is a converter that measures a physical quantity and converts it into a
signal which can be read by an observer or by an (today mostlyelectronic) instrument. For example,
a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of
a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an
output voltage which can be read by a voltmeter. For accuracy, most sensors are calibrated against
knownstandards.
Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and
lamps which dim or brighten by touching the base. There are also innumerable applications for sensors
11

of which most people are never aware. Applications include cars, machines, aerospace, medicine,
manufacturing and robotics.
A sensor is a device which receives and responds to a signal when touched. A sensor's sensitivity
indicates how much the sensor's output changes when the measured quantity changes. For instance, if
the mercury in a thermometer moves 1 cm when the temperature changes by 1 °C, the sensitivity is
1 cm/°C (it is basically the slope Dy/Dx assuming a linear characteristic).
A good sensor obeys the following rules:
•

Is sensitive to the measured property only

•

Is insensitive to any other property likely to be encountered in its
application

•

Does not influence the measured property

The sensitivity is then defined as the ratio between output signal and measured property. For example,
if a sensor measures temperature and has a voltage output, the sensitivity is a constant with the unit
[V/K]; this sensor is linear because the ratio is constant at all points of measurement.
2.2 Sensor deviations:
If the sensor is not ideal, several types of deviations can be observed:
1) Sensitivity error
2) An offset or bias.
3) Non linearity.
4) Dynamic error.
5) Drift (telecommunication).
6) Long term drift
7) Noise
8) Hysteresis
9) Aliasing errors.

All these deviations can be classified as systematic errors or random errors.
12

2.3 Resistance thermometer:

Resistance thermometers, also called resistance temperature detectors (RTDs), are sensors used to
measure temperature by correlating the resistance of the RTD element with temperature. Most RTD
elements consist of a length of fine coiled wire wrapped around a ceramic or glass core. The element is
usually quite fragile, so it is often placed inside a sheathed probe to protect it. The RTD element is made
from a pure material, platinum, nickel or copper. The material has a predictable change in resistance as
the temperature changes; it is this predictable change that is used to determine temperature.
They are slowly replacing the use of thermocouples in many industrial applications below 600 °C, due to
higher accuracy and repeatability.
2.4 R Vs T relationship of various metals
Common RTD sensing elements constructed of platinum, copper or nickel have a unique, and repeatable
and predictable resistance versus temperature relationship (R vs T) and operating temperature range.
The R vs T relationship is defined as the amount of resistance change of the sensor per degree of
temperature change. The relative change in resistance (temperature coefficient of resistance) varies
only slightly over the useful range of the sensor.
Platinum is a noble metal and has the most stable resistance-temperature relationship over the largest
temperature range. Nickel elements have a limited temperature range because the amount of change in
resistance per degree of change in temperature becomes very non-linear at temperatures over 572 °F
(300 °C). Copper has a very linear resistance-temperature relationship, however copper oxidizes at
moderate temperatures and cannot be used over 302 °F (150 °C).
Platinum is the best metal for RTDs because it follows a very linear resistance-temperature relationship
and it follows the R vs T relationship in a highly repeatable manner over a wide temperature range. The
unique properties of platinum make it the material of choice for temperature standards over the range
of -272.5 °C to 961.78 °C, and is used in the sensors that define the International Temperature
Standard, ITS-90. Platinum is chosen also because of its chemical inertness.
The significant characteristic of metals used as resistive elements is the linear approximation of the
resistance versus temperature relationship between 0 and 100 °C. This temperature coefficient of
13

resistance is called alpha, α. The equation below defines α; its units are ohm/ohm/°C.

the resistance of the sensor at 0°C
the resistance of the sensor at 100°C
Pure platinum has an alpha of 0.003925 ohm/ohm/°C and is used in the construction of laboratory grade
RTDs. Conversely two widely recognized standards for industrial RTDs IEC 60751 and ASTM E-1137
specify an alpha of 0.00385 ohms/ohm/°C. Before these standards were widely adopted several
different alpha values were used. It is still possible to find older probes that are made with platinum that
have alpha values of 0.003916 ohms/ohm/°C and 0.003902 ohms/ohm/°C.
These different alpha values for platinum are achieved by doping; basically carefully introducing
impurities into the platinum. The impurities introduced during doping become embedded in the lattice
structure of the platinum and result in a different R vs. T curve and hence alpha value.
Calibration
To characterize the R vs T relationship of any RTD over a temperature range that represents the planned
range of use, calibration must be performed at temperatures other than 0°C and 100°C. Two common
calibration methods are the fixed point method and the comparison method.
1) Fixed point calibration
2) Comparison calibration
2.5 Element types:
There are three main categories of RTD sensors; Thin Film, Wire-Wound, and Coiled Elements. While
these types are the ones most widely used in industry there are some places where other more exotic
shapes are used, for example carbon resistors are used at ultra low temperatures (-173 °C to -273 °C).
1) Carbon resistor elements
2) Strain free elements
3) Thin film elements
4) Wire-wound elements

14

5) Coiled elements
The current international standard which specifies tolerance, and the temperature-to-electrical
resistance relationship for platinum resistance thermometers is IEC 60751:2008, ASTM E1137 is also
used in the United States. By far the most common devices used in industry have a nominal resistance of
100 ohms at 0 °C, and are called Pt100 sensors ('Pt' is the symbol for platinum). The sensitivity of a
standard 100 ohm sensor is a nominal 0.385 ohm/°C. RTDs with a sensitivity of 0.375 and 0.392 ohm/°C
as well as a variety of others are also available.
2.6 Function:
Resistance thermometers are constructed in a number of forms and offer greater
stability, accuracy and repeatability in some cases than thermocouples. While thermocouples use
the Seebeck effect to generate a voltage, resistance thermometers use electrical resistance and require
a power source to operate. The resistance ideally varies linearly with temperature.
The platinum detecting wire needs to be kept free of contamination to remain stable. A platinum wire or
film is supported on a former in such a way that it gets minimal differential expansion or other strains
from its former, yet is reasonably resistant to vibration. RTD assemblies made from iron or copper are
also used in some applications. Commercial platinum grades are produced which exhibit atemperature
coefficient of resistance 0.00385/°C (0.385%/°C) (European Fundamental Interval). [8] The sensor is
usually made to have a resistance of 100 Ω at 0 °C. This is defined in BS EN 60751:1996 (taken from IEC
60751:1995). The American Fundamental Interval is 0.00392/°C, [9] based on using a purer grade of
platinum than the European standard. The American standard is from the Scientific Apparatus
Manufacturers Association (SAMA), who are no longer in this standards field. As a result the "American
standard" is hardly the standard even in the US.
Measurement of resistance requires a small current to be passed through the device under test. This can
cause resistive heating, causing significant loss of accuracy if manufacturers' limits are not respected, or
the design does not properly consider the heat path. Mechanical strain on the resistance thermometer
can also cause inaccuracy. Lead wire resistance can also be a factor; adopting three- and four-wire,
instead of two-wire, connections can eliminate connection lead resistance effects from measurements
(see below); three-wire connection is sufficient for most purposes and almost universal industrial
practice. Four-wire connections are used for the most precise applications.

15

2.7 Advantages and limitations
The advantages of platinum resistance thermometers include:
1) High accuracy
2) Low drift
3) Wide operating range
4) Suitability for precision applications.
Limitations:
RTDs in industrial applications are rarely used above 660 °C. At temperatures above 660 °C it becomes
increasingly difficult to prevent the platinum from becoming contaminated by impurities from the metal
sheath of the thermometer. This is why laboratory standard thermometers replace the metal sheath
with a glass construction. At very low temperatures, say below -270 °C (or 3 K), because there are very
few phonons, the resistance of an RTD is mainly determined by impurities and boundary scattering and
thus basically independent of temperature. As a result, the sensitivity of the RTD is essentially zero and
therefore not useful.
Compared to thermistors, platinum RTDs are less sensitive to small temperature changes and have a
slower response time. However, thermistors have a smaller temperature range and stability.
2.8 Sources of error:
The common error sources of a PRT are:
1) Interchangeability
2) Insulation Resistance
3) Stability
4)

Repeatability

5) Hysteresis
6) Stem Conduction
7) Calibration/Interpolation

16

8) Lead Wire
9) Self Heating
10) Time Response
11) Thermal EMF

2.9 RTDs vs thermocouples:
The two most common ways of measuring industrial temperatures are with resistance temperature
detectors (RTDs) and thermocouples. Choice between them is usually determined by four factors.
1) Temperature
2) Response time
3) Size
4) Accuracy and stability requirements
2.10 Construction:

FIG 2.10.1 CONSTRUCTION OF RTD
These elements nearly always require insulated leads attached. At temperatures below about 250 °C
PVC, silicon rubber or PTFE insulators are used. Above this, glass fibre or ceramic are used. The
measuring point, and usually most of the leads, require a housing or protective sleeve, often made of a
metal alloy which is chemically inert to the process being monitored. Selecting and designing protection
sheaths can require more care than the actual sensor, as the sheath must withstand chemical or physical
attack and provide convenient attachment points.
Wiring configurations
Two-wire configuration
Three-wire configuration
17

Four-wire configuration

2.11 Classifications of RTDs:
Standard platinum Resistance Thermometers (SPRTs).
Secondary Standard platinum Resistance Thermometers (Secondary SPRTs).
Industrial PRTs
2.12 Applications:

Sensor

assemblies can be categorized into two groups by how they are installed or interface with the process:
immersion or surface mounted.
1) Immersion sensors
2) Surface mounted sensors
Immersion sensors generally have the best measurement accuracy because they are in direct contact
with the process fluid. Surface mounted sensors are measuring the pipe surface as a close
approximation of the internal process fluid.
2.13 History:
The application of the tendency of electrical conductors to increase their electrical resistance with rising
temperature was first described by Sir William Siemens at the Bakerian Lecture of 1871 before the Royal
Society of Great Britain. The necessary methods of construction were established by Callendar , Griffiths,
Holborn and Wein between 1885 and 1900.
Resistance thermometer elements can be supplied which function up to 1000 °C. The relation between
temperature and resistance is given by the Callendar-Van Dusen equation,

Here, is the resistance at temperature T, is the

resistance at 0 °C, and the constants (for an

alpha=0.00385 platinum RTD) are

18

Since the B and C coefficients are relatively small, the resistance changes almost linearly with the
temperature.

2.14 Pt100 Platinum Resistance Thermometers(Pt100 SENSORS):
Platinum resistance thermometers (PRTs) offer excellent accuracy over a wide temperature range (from200 to +850 °C). Standard Sensors are are available from many manufacturers with various accuracy

specifications and numerous packaging options to suit most applications. Unlike thermocouples, it
is not necessary to use special cables to connect to the sensor.
The principle of operation is to measure the resistance of a platinum element. The most common type
(PT100) has a resistance of 100 ohms at 0 °C and 138.4 ohms at 100 °C. There are also PT1000 sensors
that have a resistance of 1000 ohms at 0 °C.
The relationship between temperature and resistance is approximately linear over a small temperature
range: for example, if you assume that it is linear over the 0 to 100 °C range, the error at 50 °C is 0.4 °C.
For precision measurement, it is necessary to linearise the resistance to give an accurate temperature.
The most recent definition of the relationship between resistance and temperature is International
Temperature Standard 90 (ITS-90).

FIG
2.14.1
SENSOR
This linearisation is done
automatically, in software,
when using Pico signal
19

Pt100

conditioners. The linearisation equation is:
Rt = R0 * (1 + A* t + B*t2 + C*(t-100)* t3)
Where:
Rt is the resistance at temperature t,
R0 is the resistance at 0°C, and
A=3.9083E-3
B =-5.775E-7
C =-4.183E-12(below0°C),or
C = 0 (above 0 °C)
For a PT100 sensor, a 1 °C temperature change will cause a 0.384 ohm change in resistance, so even a
small error in measurement of the resistance (for example, the resistance of the wires leading to the
sensor) can cause a large error in the measurement of the temperature. For precision work, sensors
have four wires- two to carry the sense current, and two to measure the voltage across the sensor
element. It is also possible to obtain three-wire sensors, although these operate on the (not necessarily
valid) assumption that the resistance of each of the three wires is the same.
The current through the sensor will cause some heating: for example, a sense current of 1 mA through
a 100 ohm resistor will generate 100 µW of heat. If the sensor element is unable to dissipate this heat, it
will report an artificially high temperature. This effect can be reduced by either using a large sensor
element, or by making sure that it is in good thermal contact with its environment.
For example, a 100 µV voltage measurement error will give a 0.4 °C error in the temperature reading.
Similarly, a 1 µA error in the sense current will give 0.4 °C temperature error.
Because of the low signal levels, it is important to keep any cables away from electric cables, motors,
switchgear and other devices that may emit electrical noise. Using screened cable, with the screen
grounded at one end, may help to reduce interference. When using long cables, it is necessary to check
that the measuring equipment is capable of handling the resistance of the cables. Most equipment can
cope with up to 100 ohms per core.

20

The type of probe and cable should be chosen carefully to suit the application. The main issues are the
temperature range and exposure to fluids (corrosive or conductive) or metals. Clearly, normal solder
junctions on cables should not be used at temperatures above about 170 °C.
Sensor manufacturers offer a wide range of sensors that comply with BS1904 class B (DIN 43760): these
sensors offer an accuracy of ±0.3 °C at 0 °C. For increased accuracy, BS1904 class A (±0.15 °C) or tenth–
DIN sensors (±0.03 °C). Companies like Isotech can provide standards with 0.001 °C accuracy. Please
note that these accuracy specifications relate to the SENSOR ONLY: it is necessary to add on any error in
the measuring system as well.
The function for temperature value acquisition (C++)
The following code estimates a Pt100 or Pt1000 sensor's temperature from its current resistance (input
parameter r).
float GetPt100Temperature(float r)
{
float const Pt100[] = { 80.31, 82.29, 84.27, 86.25, 88.22, 90.19, 92.16, 94.12, 96.09, 98.04,
100.0, 101.95, 103.9, 105.85, 107.79, 109.73, 111.67, 113.61, 115.54, 117.47,119.4, 121.32, 123.24,
125.16, 127.07, 128.98, 130.89, 132.8, 134.7, 136.6,138.5, 140.39, 142.29, 157.31, 175.84, 195.84 };
int t = -50, i = 0, dt = 0;
if (r > Pt100[0])
while (250 > t)
{
dt = (t < 110) ? 5 : (t > 110) ? 50 : 40;
if (r < Pt100[++i])
return t + (r - Pt100[i-1]) * dt / (Pt100[i] - Pt100[i-1]);
t += dt;
};
return t;
}
float GetPt1000Temperature(float r)
{
return GetPt100Temperature(r / 10);
21

3.2 What Are the Different Types of
Controllers, and How Do They Work?
3.1 Introduction to Temperature Controllers

There are three basic types of

How do Temperature Controllers work?

controllers: on-off, proportional and

To accurately control process temperature without extensive operator

PID. Depending upon the system to

involvement, a temperature control system relies upon a controller,

be controlled, the operator will be

which accepts a temperature sensor such as a thermocouple or RTD as

able to use one type or another to

input. It compares the actual temperature to the desired control

control the process.

temperature, or set point, and provides an output to a control element.
The controller is one part of the entire control system, and the whole

On/Off Control

system should be analyzed in selecting the proper controller. The

An on-off controller is the simplest

following items should be considered when selecting a controller:

form of temperature control device.

1. Type of input sensor (thermocouple, RTD) and temperature

The output from the device is either
on or off, with no middle state. An

range
2. Type of output required (electromechanical relay, SSR, analog

on-off controller will switch the
output only when the temperature

output)

crosses the setpoint. For heating
3. Control algorithm needed (on/off, proportional, PID)

control, the output is on when the

temperature is below the setpoint,
4. Number and type of outputs (heat, cool, alarm, limit)
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. On-off control is
usually used where a precise control is not necessary, in systems which cannot handle having the energy turned
on and off frequently, where the mass of the system is so great that temperatures change extremely slowly, or for
a temperature alarm. One special type of on-off control used for alarm is a limit controller. This controller uses a
latching relay, which must be manually reset, and is used to shut down a process when a certain temperature is
23

reached.
Proportional Control
Proportional controls are designed to eliminate the cycling associated with on-off control. A proportional
controller decreases the average power supplied to the heater as the temperature approaches setpoint. This has
the effect of slowing down the heater so that it will not overshoot the setpoint, but will approach the setpoint and
maintain a stable temperature. This proportioning action can be accomplished by turning the output on and off for
short time intervals. This "time proportioning" varies the ratio of “on” time to "off" time to control the
temperature. The proportioning action occurs within a “proportional band” around the setpoint temperature.
Outside this band, the controller functions as an on-off unit, with the output either fully on (below the band) or
fully off (above the band). However, within the band, the output is turned on and off in the ratio of the
measurement difference from the setpoint. At the setpoint (the midpoint of the proportional band), the output
on:off ratio is 1:1; that is, the on-time and off-time are equal. if the temperature is further from the setpoint, the
on- and off-times vary in proportion to the temperature difference. If the temperature is below setpoint, the
output will be on longer; if the temperature is too high, the output will be off longer.
PID Control
The third controller type provides proportional with integral and derivative control, or PID. This controller
combines proportional control with two additional adjustments, which helps the unit automatically compensate
for changes in the system. These adjustments, integral and derivative, are expressed in time-based units; they are
also referred to by their reciprocals, RESET and RATE, respectively. The proportional, integral and derivative terms
must be individually adjusted or “tuned” to a particular system using trial and error. It provides the most accurate
and stable control of the three controller types, and is best used in systems which have a relatively small mass,
those which react quickly to changes in the energy added to the process. It is recommended in systems where the
load changes often and the controller is expected to compensate automatically due to frequent changes in
setpoint, the amount of energy available, or the mass to be controlled.
OMEGA offers a number of controllers that automatically tune themselves. These are known as autotune
controllers.
Standard Sizes
Since temperature controllers are generally mounted inside an instrument panel, the panel must be cut to
accommodate the temperature controller. In order to provide interchangeability between temperature
24

controllers, most temperature controllers are designed to standard DIN sizes. The most common DIN sizes are
shown below.

FIG
3.2.1 STANDARD
PANEL SIZES
3.3 SELEC TC303:
Selec TC303
temperature
controller is a
single set point
controller.
//Manufacturer
SELEC Controls Pvt. Ltd Code No SELEC TC303//
Features:
Single display
4 digits
7 segment LED
TC / RTD input PID
ON/OFF control
Single set point °C / °F
selectable Field selectable control output (Relay or SSR)
Auxiliary output: Relay

25

Easy to use.FF
SFIG 3.3.1 TEMPERATURE READER
(CONTROLLER)
FIGFI

CHAPTER4

26

PIC16F877A and RS232

4.1 PIC16F877A:
This powerful (200 nanosecond instruction execution) yet easy-to-program (only 35 single word
instructions) CMOS FLASH-based 8-bit microcontroller packs Microchip's powerful PIC® architecture into
an 40- or 44-pin package and is upwards compatible with the PIC16C5X, PIC12CXXX and PIC16C7X
devices. The PIC16F877A features 256 bytes of EEPROM data memory, self programming, an ICD, 2
Comparators, 8 channels of 10-bit Analog-to-Digital (A/D) converter, 2 capture/compare/PWM
functions, the synchronous serial port can be configured as either 3-wire Serial Peripheral Interface
(SPI™) or the 2-wire Inter-Integrated Circuit (I²C™) bus and a Universal Asynchronous Receiver
Transmitter (USART). All of these features make it ideal for more advanced level A/D applications in
automotive, industrial, appliances and consumer applications.
Features

2 PWM 10-bit
256 Bytes EEPROM data memory
ICD
25mA sink/source per I/O
Self Programming
Parallel Slave Port
Parameter Name

Value

Program Memory Type

Flash

Program Memory (KB)

14
27

CPU Speed (MIPS)

5

RAM Bytes

368

Data EEPROM (bytes)

256

Digital Communication Peripherals

1-A/E/USART, 1-MSSP(SPI/I2C)

Capture/Compare/PWM Peripherals

2 CCP

Timers

2 x 8-bit, 1 x 16-bit

ADC

8 ch, 10-bit

Comparators

2

Temperature Range (C)

-40 to 125

Operating Voltage Range (V)

2 to 5.5

Pin Count

40
TABLE 4.1.1 FEATURES OF PIC16F877A

FIG 4.1.1 PIC16F877A
4.2 RS232:
In telecommunications, RS232 is the traditional name for
a series of standards for serial
binary singleended data and control signals connecting between a DTE (data terminal equipment) and a DCE (data
circuit-terminating equipment). It is commonly used in computer serial ports. The standard defines the
electrical characteristics and timing of signals, the meaning of signals, and the physical size and pinout of
connectors. The current version of the standard is TIA-232-F Interface between Data Terminal
Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, issued in
1997.
An RS-232 serial port was once a standard feature of a personal computer, used for connections
28

to modems, printers, mice, data storage, uninterruptible power supplies, and other peripheral devices.
However, the low transmission speed, large voltage swing, and large standard connectors motivated
development of the Universal Serial Bus, which has displaced RS-232 from most of its peripheral
interface roles. Many modern personal computers have no RS-232 ports and must use an external USBto-RS-232 converter to connect to RS-232 peripherals. RS-232 devices are still found, especially in
industrial machines, networking equipment, or scientific instruments.
History
RS-232 was first introduced in 1962 by the Radio Sector of the EIA. The original DTEs were
electromechanical teletypewriters, and the original DCEs were (usually) modems. When electronic
terminals (smart and dumb) began to be used, they were often designed to be interchangeable with
teletypewriters, and so supported RS-232. The C revision of the standard was issued in 1969 in part to
accommodate the electrical characteristics of these devices.
Many fields (for example, laboratory automation, surveying) provide a continued demand for RS-232 I/O
due to sustained use of very expensive but aging equipment. It is often far cheaper to continue to use
RS-232 than it is to replace the equipment. Additionally, modern industrial automation equipment, such
as PLCs, VFDs, servo drives, and CNC equipment are programmable via RS-232. Some manufacturers
have responded to this demand: Toshiba re-introduced the DE-9M connector on the Tecra laptop.
Serial ports with RS-232 are also commonly used to communicate to headless systems such as servers,
where no monitor or keyboard is installed, during boot when operating system is not running yet and
therefore no network connection is possible. An RS-232 serial port can communicate to some embedded
systems such as routers as an alternative to network mode of monitoring.

Signals:
The following table lists commonly used RS-232 signals and pin assignments. [9] See serial port
(pinouts) for non-standard variations including the popular DE-9 connector.
Signal
Name
Data Terminal

Origin

Typical purpose

Abbreviation

Indicates presence of DTE to DCE.
29

DTE

DTR

●

DCE

DB-25 pin
20

Ready
Data Carrier

DCE is connected to the telephone line.

Data Set Ready

DCD

●

8

DCE is ready to receive commands or data.

Detect

DSR

●

6

RI

●

22

DCE has detected an incoming ring signal on

Ring Indicator

the telephone line.

Request To Send
Clear To Send

DTE requests the DCE prepare to receive
data.
Indicates DCE is ready to accept data.

RTS

●

4
●

CTS
●

5

Transmitted Data Carries data from DTE to DCE.

TxD

Received Data

RxD

●

3

Common Ground

GND

common

7

Protective Ground

PG

common

1

Carries data from DCE to DTE.

2

TABLE 4.2.1 SIGNALS IN RS232

The signals are named from the standpoint of the DTE. The ground signal is a common return for the
other connections. The DB-25 connector includes a second "protective ground" on pin 1.
Data can be sent over a secondary channel (when implemented by the DTE and DCE devices), which is
equivalent to the primary channel.
Pin assignments are described in following table:
Signal

Pin

Common Ground

7 (same as primary)

Secondary Transmitted Data (STD)

14

Secondary Received Data (SRD)

16

Secondary Request To Send (SRTS)

19

Secondary Clear To Send (SCTS)

13

Secondary Carrier Detect (SDCD)

12

TABLE 4.2.2 PIN ASSIGNMENTS
Ring Indicator' (RI), is a signal sent from the modem to the terminal device. It indicates to the terminal
30

device that the phone line is ringing. In many computer serial ports, a hardware interrupt is generated
when the RI signal changes state.
Certain personal computers can be configured for wake-on-ring, allowing a computer that is suspended
to answer a phone call.
Cables:
The standard does not define a maximum cable length but instead defines the maximum capacitance
that a compliant drive circuit must tolerate. A widely used rule of thumb indicates that cables more than
50 feet (15 m) long will have too much capacitance, unless special cables are used. By using lowcapacitance cables, full speed communication can be maintained over larger distances up to about 1,000
feet (300 m). For longer distances, other signal standards are better suited to maintain high speed.
Other serial interfaces similar to RS-232:
RS-422 (a high-speed system similar to RS-232 but with differential signaling)
RS-423 (a high-speed system similar to RS-422 but with unbalanced signaling)
RS-449 (a functional and mechanical interface that used RS-422 and RS-423 signals - it never caught on
like RS-232 and was withdrawn by the EIA)
RS-485 (a descendant of RS-422 that can be used as a bus in multidrop configurations)
MIL-STD-188 (a system like RS-232 but with better impedance and rise time control)
EIA-530 (a high-speed system using RS-422 or RS-423 electrical properties in an EIA-232 pinout
configuration, thus combining the best of both; supersedes RS-449)
EIA/TIA-561 8 Position Non-Synchronous Interface Between Data Terminal Equipment and Data Circuit
Terminating Equipment Employing Serial Binary Data Interchange
EIA/TIA-562 Electrical Characteristics for an Unbalanced Digital Interface (low-voltage version of EIA/TIA232)
TIA-574 (standardizes the 9-pin D-subminiature connector pinout for use with EIA-232 electrical

31

signalling, as originated on the IBM PC/AT)
SpaceWire (high-speed serial system designed for use on board spacecraft).
Serial line analyzers are available as standalone units, as software and interface cables for generalpurpose logic analyzers, and as programs that run in common personal computers.

FIG 4.2.1 RS232 cable

CHAPTER 5

32

GRAPHICAL DISPLAY

5.1 Graphical LCD 128*64:
Description:
This is a framed graphical LCD 128*64 with LED backlight. This unit is a very clear STN type
LCD with a simple command interface. This new module includes the negative voltage circuitry
on board!
Dimensions:
•

Overall: 75x52.7mm

•

Viewable area: 55.01x27.49mm

FIG 5.1.1
Graphical
LCD 128*64
5.2 Interfacing of PIC16F877A
with 128x64 graphical display:
Components/ Softwares:
MPLAB IDE (PIC microcontrollers simulator) PIC BURNER 3 with software to load the code LCD
(Displaytech 162A) Computer System with Windows operating system and RS 232 cable PIC16F877
Microcontroller +5V D.C Power Supply Resistors - 10K Ω-1,50Ω-1 Capacitors - 27 µ F-2 Potentiometers 34

10K Ω -1 20MHz Crystal oscillator SPST switches -1
Procedure:
Write the assembly code in MPLAB IDE simulator , compile it and check for errors Once the code was
error free, run it and check the output in the simulator. After checking the code in the simulator, load
the code (in .HEX format) into PIC16F877 microcontroller using PIC BURNER3. Make connections as
shown in the circuit diagram. Switch on the power supply and observe "IITK" displayed in the LCD.
Initializing LCD by sequence of instructions Executing commands depending on our settings in the LCD
Writing data into the DRAM locations of LCD in the Standard Character Pattern of LCD
MPLABIDE is a free software which can be downloaded from the websitewww.microchip.com
Working with MPLABIDE :
MPLABIDE is a simulator for PIC microcontrollers to write and edit the code in assembly language,
compile it and also to run the code. Output can be verified using simulator. Steps to Use MPLABIDE
After Installing the software MPLABIDEv7.2, open MPLABIDE. To built a new project, open Project
Project Wizard Project wizard New Device 16F877 Location (C:ProgramFiles-MicrochipMPASM
SuiteMPASMWIN.EXE) Next <Project name>&<Project Directory> Next (Add file "f877tmpo.asm" which
was located in programfiles microchip MPASM Suite Template Object) (Add file "16f877.lkr" which was
located in program files microchip MPASM Suite LKR) Next Finish To have more clear refer to MPLABIDE
help files. After building the project open the editor f877tmpo.asm and write the assembly code After
writing the assembly code in the editor, build the project by clicking on the following option Project
Build all Check for the errors in the output window View Output Once the error free code was made,
simulate the code by following option Debugger Select Tool MPLAB SIM Simulator options are Step into
- Each time only one instruction will be executed (Single stepping mode) Run - To run the whole code at
once. Animate - to animate the executing the code Additional things: To view DRAM, program memory,
SFRs, and External memory use the option VIEW To set break points in the code (where simulation stops
at that point). Debugger Breakpoints To stop the simulation Debugger Halt
After checking the code in the simulator, the code (file with .HEX extension) is loaded into 16F877
35

microcontroller using PIC BURNER 3. PIC BURNER3
PIC BURNER3 can be used to program PIC microcontrollers. The steps to be followed to program the IC
safely are as follows.
Connect the PIC BURNER3 through RS232 Port to computer system with windows98 as operating
system. Execute the file "icprog" which was in the software that comes with PIC BURNER3. Set the
device as PIC16F877 Switch on the power supply of PIC BURNER3 Settings Hardware { JDM
Programmer,Com1,Direct I/O} Settings Hardware check 1. on clicking "Enable Data out", Data in must be
clicked automatically 2. on clicking Enable MCLR, red LED on the PICBURNER3 must glow Settings
Options Confirmation [ Erasing the devise,Code Protecting the Devise] Settings Options MISC Process
Priority Normal Settings Options Programming Verify After Programming. Remaining options keep them
at default settings. [Refer Manual of PICBURNER3 for detail] Now insert the 16F877 microcontroller into
the slot provided on the PICBURNER3 as the direction specified in the manual of PICBURNER3. load
the .hex file File open file Command Erase All Command Blank Check Then there should be a notice on
the window that "Device is Blank " Command Program All Command Blank Check Then there should be a
notice on the window that "Device is not blank at address 0x0000H". Close the window, remove the IC
from the PIC BURNER3 and switch off the power supply for PIC BURNER3.

FIG5.2.1 Interfacing of
PIC16F877A with 128x64
graphical display
CHAPTER6

36

PROCEDURE
6.1 PROCEDURE:
Ensure proper electrical connections.
Place the sensor (tip probe) in a heat source.
It will be read and shown in selecTC303.
Then, the output from it is given to the microcontroller and program gets
executed.
From the PIC16F877A, RS232 cable is linked to system and values are seen.
Then, it is given to graphical display.

FIG6.1 BLOCK DIAGRAM OF TEMPERATURE
MEASUREMENT SETUP:
TEMPERATURE
SENSOR
(Pt100)

TEMPERATURE
READER/CONTROLLER

PIC16F877A
MICROCONTROLLER
37

RS232

128*64
GRAPHICAL
DISPLAY
UNIT

COST ESTIMATION:
Sensor
Temperature controller
Microcontroller chip(kit)
Graphical display

Rs.480
Rs.1200
Rs.2500
Rs.800

CONCLUSION

This can be used for measuring, controlling and acquisition of the temperatures in the
engineering systems such as IC Engines, Boilers, etc. Graphs can be drawn between a
temperature and time.

38

Project report on design and fabrication of temperature measurement setup

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Project report on design and fabrication of temperature measurement setup