Download Controller based Temperature Monitoring System

Controller based Temperature Monitoring System
Jay H. Bhut1, Dharmrajsinh Parmar2
1
ME student of MEFGI, Rajkot, Gujarat - India. Email: [email protected]
M.Tech. Student of CSPIT, Changa, Gujarat - India. Email: [email protected]
2
Abstract: Monitor and control the temperature is an important factor in industrial environments. Sensors are
widely used for measurement of temperature. This paper describes a temperature controller where the user can
pre-adjust the temperature or can give a condition to maintain the temperature of an instrument or of any
instrument body. In addition it records temperature variations in PC using serial communication. The controller
can be easily adapted to different environment and actuating systems to fulfil the local requirements.
Keyword: Microcontroller (PIC), Temperature Sensor (LM35), ADC.
1.
INTRODUCTION
The temperature is one of the important factors which
need to control and monitor as it often affect some
scientific experiments and instruments reading in the
laboratory where an investigation performs. There are
many different cases where the quality of the
experiments depends on a reliable Temperature
control [2].
There are the adaptive requirements which lead us to
include different hardware components as: 1.A
controller board, 2.A Temperature Sensor, 3.A
Personal Computer, and 4.The appropriate Software.
From these a controller board is required to control
the peripheral activity which connected to it. A
temperature sensor is mainly used to measure the
temperature of an instrument body where it connected
and it gives the output in an analog form and output of
that given to A/D IC to convert it into digital form.
2.
TEMPERATURE CONTROLLER
USING PIC:
The controller used in this work is microchip’s PIC
controller which is more popular one among the other
controller so, it also called as industry standard
controller. The other main thing to use PIC controller
is it has inbuilt analog to digital channel which
removes the requirement of an external Analog to
Digital (ADC) IC to convert analog output of a sensor
into digital to give it to a controller as an input [3].
From this one can maintain a temperature through
coil, heater or fan by keeping a condition in controller.
A personal computer is used to display and store the
temperature and to provide quick and easy access
using the RS232 cable of a serial communication to
the mentioned board. Software used to calculate the
temperature through pin connected with a sensor and
set the parameters and maintain the constant
temperature by triggering voltage of the pin which
connected to heater or coil. Software also used to
display the recorded information of temperature
variations and serve a communication link between
the control board and the PC.
Fig 1: Functional Block Diagram of Temperature
Controller
This paper is organized as follows: in the first section
it describes the sensors and control board, which form
the hardware of the system. In the following one that
gives an outline of a mathematical calculation for
calculating the temperature. In the next following
section brief intro of software is provided. Finally, in
the last section it concludes the paper.
Sensors are widely used to measure the room
temperature or of an instrument body. Usually,
temperature sensors are of two types by seeing its
output as some gives voltage whereas few give in
current. LM35 is a one of the popular temperature
sensor which gives its output by converting
temperature into appropriate voltage.
In this presented work temperature controller
describes based on PIC16F887 and LM35 temperature
sensor. A description of a simple temperature
measurement and a display system is described in this
paper.
The above functional block diagram shows a
temperature controller system which having different
blocks which connected to the controller to perform
different functions as explained below. 5V power
supply connected to controller to supply the power
and reset circuit used to reset the circuit. Here from
above block diagram Crystal frequency block
connected to controller is optional as PIC controller
has also an internal crystal oscillator of up to 8MHz.
Personal computer is used to display and store the
temperature data into database throughout the whole
day using serial communication. One can also use a
LCD display and keypad to only display the
temperature without using any serial port. At last Coil
or Heater used as a cooling part to keep maintain the
temperature of an instrument body as per controller
instruction through software. The 10 bit of inbuilt
ADC converter is used in PIC controller to convert
the analog output of LM35 into equivalent digital
sequence and which removes the requirement of an
external ADC IC as it need in other low level
controller.
LM35 temperature sensor’s pin configuration is as
shown in below figure. LM35 temperature sensor
gives temperature in voltage which is linearly
proportional to the temperature in oC (centigrade).
Thus, this is one of the advantages of LM35 over
other which gives temperature in to oK (kelvin), as the
user need to convert it to centigrade [4].
has a linear 10mV/oC of scale factor. So, one can say
that there is a 0V for 0oC and 1V for 100oC [4].
The microcontroller has 10 bit of A/D converter
which gives equivalent digital 10 bits of output which
need to convert into appropriate temperature using
some mathematical calculation as given below [1].
Here reference voltage taken as 5V which is same as
supply voltage of the controller and if we say the
digital 10 bits of output as ADCVoltage then the
voltage comes from the pin is as calculated below.
Voltage (V) =
𝐴𝐷𝐶𝑉𝑜𝑙𝑡𝑎𝑔𝑒
1024
𝑋 5……1
Here 1024 is the 210 as controller has 10 bits of inbuilt
analog to digital channel. So, ADCVoltage divided
with 210 bit and multiply with the reference voltage of
5V. So, the voltage comes from the calculation is
equivalent to the temperature which comes from the
temperature sensor. Now as the linear scale factor of
LM35 is in the mV so to convert the above voltage
into mV it multiplied with the 1000 as shown below.
Voltage (mV) =
𝐴𝐷𝐶𝑉𝑜𝑙𝑡𝑎𝑔𝑒
1024
𝑋 5 𝑋 1000….2
Now as we know the scale factor of LM35 is
10mV/oC. It means that 10mV of temperature varies
per oC (Simply 10mV = 1oC). So, to get above
equation in degree centigrade we divide it with 10 as
from its scale factor.
Temperature (oC) =
𝐴𝐷𝐶𝑉𝑜𝑙𝑡𝑎𝑔𝑒
𝑋 5 𝑋 1000
1024
10
….3
The simple explanation of above equation can be
drawn as by showing it as simple calculation as “If
1oC for 10mV then how many centigrade for above
given voltage in equation 2.”
So, at final the simple equation can be drawn from
above is written as below equation 4 for reference
voltage of 5V.
Temperature (oC) =
4.
Fig 2: LM35 Pin Diagram
3.
MATHEMATICAL CALCULATION
For each degree Celsius change in temperature, the
sensor output changes by 0.01V due to LM35 Sensor
𝐴𝐷𝐶𝑉𝑜𝑙𝑡𝑎𝑔𝑒
1024
𝑋 500….4
SOFTWARE DESCRIPTION
The software code is used to done all this
mathematical calculation as shown in above section.
The software code in present work is written in ‘C’
language using Hi tech c compiler in MPLAB X IDE.
The MS Visual Studio used to create a GUI and to
store temperature data into database. The RS232 port
is used for make serial communication between
controller and personal computer. The flow chart for
software steps is as shown in below flow chart.
5.
CONCLUSION
The work, presented here drawn from the
investigations and implementation that have been
done so far and it is also intended to be of some use in
Small Scale industries, laboratories, or in small
research organization, etc. because Instrument
Automation is often Requirement by industry
especially in smaller research institutions where the
cost is matter. This paper designed in such a way so
that it will helpful to user to make temperature
controller and monitoring system using any different
peripheral and controller also by taking the basic idea
given in presented work.
6.
REFERENCES
[1] AnshumAn BezBorAh, “PIC16F877A-based
Temperature monitoring system”, Electronics for
you magazine, www.efyMag.coM
[2] R. López, S. Galindo, E. Gaytán, R. Juárez,
TEMPERATURE
AND
HUMIDITY
LABORATORY REMOTE CONTROLLER,
Journal of the Mexican Society of
Instrumentation, Vol. 3 Nr. 6/1996, pp 14-20
[3] PIC16F882/3/4/6/7 Datasheet – Microchip
Technology
http://ww1.microchip.com/downloads/en/Device
Doc/41291D.pdf
[4] LM35 Datasheet – National Semiconductor
http://pdf1.alldatasheet.com/datasheetpdf/view/8866/NSC/LM35.html
Fig 2: Flow Chart for temperature monitoring system