centralized power monitoring system report

7/30/2019 Centralized Power Monitoring System Report

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CENTRALIZED POWER MONITORING SYSTEM

1 | P a g e N I L O T P A L M R I N A L

CHAPTER-1

INTRODUCTION


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INTRODUCTION

In this project an attempt has been made to observe consumption of Electrical energy b

means of an energy meter and the data is sent to a computer. Energy meter is generally o

the electro-dynamic type. An electronic type of energy meter is used. The calculation circuis a PCB which calculates the power consumption of each appliance which is connected

explicitly. CALCULATION CIRCUIT would be installed at the back of switch boxes.

Two transformers a voltage and a current transformer each samples current and voltage i

used to deliver voltage and current to calculate energy consumed in KWH. The circuit ca

handle up to 20A current. The meter converts energy consumed to pulses of resolution 6.4

Imp/Wh. The pulses converted are then transmitted to modulator and communicated via

non-linear channel to the demodulator circuit.

At demodulator circuit, connected to personal computer, signal is demodulated and using

microcontroller sent to personal computer via LPT. A VB6 program reads port and saves th

received data to an .dat file.

A power supply unit delivers the power required by the I Cs at demodulator circuit. Powe

supply unit consists of a transformer and 78XX series voltage regulators for regulated suppl

at +5V.

Demodulation Circuit would be at back side of PC and DATA COLLECTION SOFTWARE i

PC. Altogether the energy consumption at switches will be recorded on PC.


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CHAPTER-2

BLOCK DIAGRAM


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In this chapter the idea and conceptual block diagram will be demonstrated to provide clea

understandings of the project.

2.1CONCEPT

CALCULATION CIRCUIT is installed at the back side of switch boxes, and DAT

COLLECTION SOFTWARE at PC. The calculation circuit is a PCB which will calculate th

energy consumed by each appliance which is connected. The calculation circuit is in paralle

with every switch and is to be assembled behind switch box.

Figure 2.1: Conceptual Diagram


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2.2 BLOCK DIAGRAM

The transmission media to be used is selected as telephone cable because it is economica

and has minimum loss. Demodulator is connected to PC with less than 3ft D25 connecto

cable.

The Block diagram is shown in Figure 2.2.

Figure 2.2: Block Diagram


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2.2.1 Calculation Circuit

Two transformers a voltage and a current transformer each samples current and voltage i

used to deliver voltage and current to calculate energy consumed in KWh. The circuit ca

handle up to 20A current. The meter converts energy consumed to pulses of resolution 6.4

Imp/Wh. The pulses converted are then transmitted to modulator and communicated via a

non-linear channel to the demodulator circuit.

2.2.2 Transmission Media

The transmission media to be used is selected as telephone cable because it is economica

and has minimum loss over distance.

2.2.3 Demodulator Circuit

At demodulator circuit (connected to PC), first ASK is demodulated to get the same analo

signal at the output of watt meter. Using 89C4051 the analog signal is converted and

interfaced to parallel port of PC.

2.2.4 Computer

A simple PC is used with Windows Platform installed with Pratham v7.1, a VB6 program t

control and receive data from parallel port of computer. Demodulator is connected to PC wit

less than 3ft D25 connector cable. Pratham v7.1, program reads port automatically an

saves the received data to an .ini file.

2.2.5 Power Supply unit (PSU)

Power Supply Unit consists of a Transformer (15-0-15), 7815, 7805 and 7915 voltag

regulators. It provides required power for the I Cs.


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CHAPTER-3

WORKING


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In this chapter the circuit diagrams will be explained for all of the constituent circuits. First is

calculation circuit.

3.1CALCULATION CIRCUIT

The circuit diagram of calculation circuit is shown in Figure 3.1.

Figure 3.1: Calculation Circuit

A potential and a current transformer is used to sample current and a microcontroller base

energy kit CD2299 is used to convert energy usage into pulses of resolution 6.4Im/Wh. A

electro mechanical interface shows the traditional readings. An analog MUX converts pulse

into ASK. The ASK is then transmitted to demodulator circuit that is remote to the calculatio


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circuit. An oscillator using LM353 creates sine wave at frequency 43.3 KHz. This sine wave is

used as carrier for ASK message signal.

Due to most of the transmission lines are non linear the ASK is best suited for no

synchronous modulation. However the error in ASK generation and detection results i

change of pulse width but the relevant change in pulse width does not affect the outcome

The frequency of pulse is too small, in order of few hertz hence, practically the outcome o

project merely depends upon the number of pulses which on the later circuit will be counted

after demodulation inside microcontroller programmed to perform interfacing with computer.

Error in modulation scheme is hence avoided by using microcontroller based counter.

3.2 DEMODULATOR CIRCUIT

The circuit diagram of demodulation circuit is shown in Figure 3.2.

Figure 3.2: Demodulator Circuit


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The output of calculation circuit is provided to opto-coupler which provides electric isolatio

between circuits. The output of opto-coupler is fed to an comparator using uA741 whic

demodulates ASK. A microcontroller AT89C4051 is used to count pulses and convert th

count to hexadecimal.

The hexadecimal number represents the energy consumed in resolution of 10 Wh/uni

74244 buffer is used to interface the output data of microcontroller to computers parallel po

using D25 connector. The buffer provides reading of output nibble-wise. i.e. The hexadecima

output is read one nibble at a time by VB program. The program then joins the data an

makes byte form nibbles.

3.3 POWER SUPPLY UNIT

The circuit diagram of Power Supply Unit is shown in Figure 5.

Figure 3.3: Power Supply Unit Circuit


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Power Supply Unit consists of a Transformer rated 15-0-15, three 78XX series voltag

regulators and it provide required power for the circuitry.

First a Bridge Rectifier converts AC into DC. The rectified output from bridge rectifier is then

regulated and filtered using 78XX series voltage regulators. 7815 produces +15V, 7915

produces -15V and 7805 produces +5V. Altogether the constituents provide a stable and

reliable power supply unit for I Cs. Transformer chosen is a 15-0-15, 1 Amp type. For inpu

and output filtering capacitors are used so that the ripple in output can be reduced. All diodes

are 1N4001/1N4007.

3.4 SOFTWARE

A simple PC is used with Windows Platform installed with Pratham v7.1, a VB6 program t

control and receive data from parallel port of computer. Demodulator is connected to PC wit

less than 3ft D25 connector cable. Pratham, program reads port and saves the received dat

to a .dat file.

Snapshot of the program is depicted in Figure 6.

Figure 3.4 : Main Window (Pratham v7.1)


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The software can work in two modes one is automatic another is manual. The software itse

is capable of logging data with date and time. It converts the data received to Watt-Hour and

logs it in a file at application directory under name of data.dat. It reads output nibble b

nibble and then by using a function joins nibbles to form a complete byte.


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CHAPTER 4

Components and Their Configurations


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4.1 OPERATIONAL AMPLIFIER

4.1.1 LM741

The LM741 series are general purpose operational amplifiers which feature improve

performance over industry standards like the LM709. The amplifiers offer many feature

which make their application nearly fool proof, over load protection on the input and outpu

no latch up when the common mode range is exceeded as well as freedom from oscillations.

The LM741 has their performance guaranteed over a zero degree Celsius to seventy degre

Celsius temperature range, instead of minus fifty five degree Celsius to one hundred an

twenty five degree Celsius.

Pin Diagram:

Figure 4.1: uA741 Pin Detail

LM741 is used as same as non inverting summer and for demodulation of PWM and ASK.

4.1.2 LF353

The LF353 is a JFET input operational amplifier with an internally compensated input offse

voltage. The JFET input device provides with bandwidth, low input bias currents and offse

currents.


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Pin Details:

Figure 4.2: LF353 Pin Detail

LF353 is used in differential amplifier and sine wave oscillator used in ASK. It has a high slewrate for around 30V/us, that is why it is used in sine wave generation. The circuit diagram fo

sine wave generator is depicted below if Figure 15.

Oscillation Circuit :

Figure 4.3: Oscillation Circuit Diagram

We need Vout = +/5 V thus Vcc = +/- 5V. To limit the output we use diodes so that forward

current is assumed to be 1mA.


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Design:

Requirement, Vcc = +/- 15V, Vout = +/- 5V, f = 43.3 KHz

Assume, R = 170E , C = 1 / ( 2 * pi * 2.44 * 43.3K) ...Equation 5

Therefore, chosen C = 0.1uF.

For Vout = +/- 5V,

Assume, Id = 1mA, R1 = 3V / (29 * 1mA) ......Equation 6

R3 = 2 * Vf / Id = 2 * 0.7V / 1mA, R3 = 1k4 ..Equation 7

Therefore, R4 = R2R3 = 3k6. Diodes used are OA79.

4.2 VOLTAGE REGULATOR (78XX series)

The LM 7805 series of three positive regulators are available in the TO -220 package an

with several fixed output voltages making them useful in a wide range of applications. Eac

type employs internal circuit limiting, thermal shut down and safe operating area protection

making it essentially in destructible. If adequate heat sinking is provided, they can delive

over one ampere output current. Although the design is primarily as fixed voltage regulator

this device can be used with external components to obtain adjustable voltages and currents

The LM7915 series of three terminal regulators is available with fixed output voltages of -

volt, -8 volt, -12 volt and -15 volt. This device needs only one external component

compensation capacitor at the output. The LM7915 series is packed in the TO-220 powe

package and is capable of supplying 1.5 ampere of output current.

This regulator employs internal current limiting safe area protection and thermal shut down

for protection against virtually all over load conditions.


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Pin Diagram:

Figure 4.4: 78XX Voltage Regulators

4.3 BUFFERS (74LS244)

Three state outputs drive bus lines or buffer memory address resistors, PNP inputs reduce

DC loading, hysteresis at inputs improves noise margin. This octal buffers and line driver

are designed specifically to improve both the performance and density of three state memory

address driver, clock drivers and bus oriented receivers and transmitters. The designer has

choice of selected combinations of inverting and non-inverting outputs, symmetrical G inputs

and complementary G and G^ inputs. These devices feature high fan out, improved fan in

and 400mV noise margin. The pin detail of 74244 buffer is depicted in Figure 20.


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Schematic Diagram:

Figure 4.4: 74LS244 Pin Detail

4.4 TRANSFORMER

A transformer is a static or stationary device which transfers electrical power from one circu

to another without change of frequency. The principle of working of transformer is mutua

induction between two circuits linked by a common magnetic flux.

It consists of two separate coils placed on a laminated core. These coils are electricall

separated and magnetically linked through a path of low reluctance. The two coils possesse

high mutual inductance. If any one of the two coils called primary is connected to a source o

alternating voltage, and alternating flux with the same frequency of as that of supply voltageswill set up in the wave. Most of alternating flux will be linked with the other coil called

secondary and have mutually induced EMF is produced in it. According to the faradays law

of electromagnetic induction, if the secondary circuit is closed with a load, impedance then a

current flows through it. Hence electrical power is transferred from primary to secondar

without change of frequency. In an ideal transformer, the induced voltage in secondar


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winding (Vs) is in proportion to the primary voltage (Vp), and is given by the ratio of th

number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows:

Vs/Vp=Ns/Np

Figure 21 :

Figure 4.5: Transformer Winding

Based on voltage transformation ratio or turns ratio, a transformer may be Step-u

transformer for which number of turns on secondary is greater than number of turns o

primary and in Step-down transformer, the number of turns on secondary is less than that o

primary.


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CHAPTER 5

MICROCONTROLLER AND PROGRAMMING


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5.1 MICROCONTROLLER (AT89C4051)

The AT89C4051 is a low-voltage, high-performance CMOS 8-bit microcontroller with 4K

bytes of Flash programmable and erasable read-only memory. This device is made usin

Atmels high-density nonvolatile memory technology and is compatible with the industry

standard MCS-51 instruction set. By combining a versa-tile 8-bit CPU with Flash on

monolithic chip, the Atmel AT89C4051 is a powerful microcontroller which provides a highly

flexible and cost-effective solution to many embedded control applications. The AT89C405

provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 15 I/O lines

two 16-bit timer/counters, a five-vector, two-level interrupt architecture, a full duplex seria

port, a precision analog comparator, on-chip oscillator and clock circuitry. In addition, th

AT89C4051 is designed with static logic for operation down to zero frequency and support

two software-selectable power saving modes. The Idle Mode stops the CPU while allowin

the RAM, timer/counters, serial port and interrupt system to continue functioning. The powe

down mode saves the RAM contents but freezes the oscillator disabling all other chi

functions until the next hardware reset.

RESTRICTION ON CERTAIN INSTRUCTIONS

The AT89C4051 is an economical and cost-effective member of Atmels growing family o

micro-controllers. It contains 4K bytes of Flash program memory. It is fully compatible with

the MCS-51 architecture, and can be programmed using the MCS-51 instruction se

However, there are a few considerations one must keep in mind when utilizing certai

instructions to program this device. All the instructions related to jumping or branching shoul

be restricted such that the destination address falls within the physical program memor

space of the device, which is 4K for the AT89C4051. This should be the responsibility of the

software programmer. For example, LJMP 0FE0H would be a valid instruction for th

AT89C4051 (with 4K of memory), whereas LJMP 1000H would not.

LCALL, LJMP, ACALL, AJMP, SJMP, JMP @A+DPTR. These unconditional branchin

instructions will execute correctly as long as the program keeps the destination branchin

address within the physical boundaries of the program memory size (locations 00H to FFFH

for the 89C4051). Violating the physical space limits may cause unknown program behavior.


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CJNE, DJNZ, JB, JNB, JC, JNC, JBC, JZ, JNZ. With these conditional branching instruction

the same rule above applies. Again, violating the memory boundaries may cause errati

execution. For applications involving interrupts, the normal interrupt service routine addres

locations of the 80C51 family architecture have been preserved.

POWER-DOWN MODE

In the power-down mode the oscillator is stopped and the instruction that invokes power

down is the last instruction executed. The on-chip RAM and Special Function Register

retain their values until the power-down mode is terminated. The only exit from power-dow

is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. Th

reset should not be activated before VCC is restored to its normal operating level and mus

be held active long enough to allow the oscillator to restart and stabilize.

Pin Diagram:

Figure 5.1: AT89C4051Pin Detail


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5.2 PROGRAM

The program for microcontroller is written in C. The reg51.h header file is included fo

embedded C for Atmel series microcontroller operations. At P3.4 the pulses are detected an

counter is initialized to count up to 64. Then at 65th

pulse P1 is incremented. AT80C4051 i

20 pin I C with only two ports P1 and P3. An interrupt service routine is used as subroutin

for incrementing P1.

CODE:

#include

unsigned char i=0;

void incrii() interrupt 1

{

i++ ;

}

void main ()

{

P1=00; TMOD=0x06; TL0=-64; TH0=-64; TR0=1;

T0=1; TF0=0; IE=0x82; i=0;

while(1)

{

P1=i;

}

}


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In this program T0 is set as up counter to count 64. P3.4 is chosen to receive pulses from

demodulator output. After receiving 64 pulses P1 i.e. port 1 is incremented by 1. An interrup

service routine is called for incrementing P1. Using an ISR makes it possible fo

microcontroller to work in multitasking mode The objective of counting 64 is to change the

resolution to 10WH. Later the transmitted data is received at parallel port and converted tKWh.


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CHAPTER 6

Modulation and Demodulation


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ASK (Amplitude Shift Keying)

Amplitude-shift keying (ASK) is a form ofmodulation that represents digital data as variation

in the amplitude of a carrier wave. The amplitude of an analog carrier signal varies i

accordance with the bit stream (modulating signal), keeping frequency and phase constan

The level of amplitude can be used to represents binary logic 0s and 1s. We can think of

carrier signal as an ON or OFF switch. In the modulated signal, logic 0 is represented by the

absence of a carrier, thus giving OFF/ON keying operation and hence the name given. Lik

AM, ASK is also linear and sensitive to atmospheric noise, distortions, propagatio

conditions on different routes in PSTN, etc. Both ASK modulation and demodulatio

processes are relatively inexpensive. The ASK technique is also commonly used to transm

digital data over optical fiber. For LED transmitters, binary 1 is represented by a short pulse o

light and binary 0 by the absence of light. Laser transmitters normally have a fixed bias

current that causes the device to emit a low light level. This low level represents binary 0

while a higher-amplitude light wave represents binary 1.

6.1 MODULATION

CD4051 is used to generate ASK. CD4051 is analog MUX. Select lines is connected so tha

S2 at pin 11 and S1 at pin10 is connected to ground. S0 at pin 9 is connected to output o

PWM. The signal when high gives output of sine wave of 43.3 KHz at pin as I1 at pin is fed

with output of LF353 oscillator. The circuit diagram of ASK generation is shown in Figure 23.

CIRCUIT DIAGRAM:

Figure 6.1: ASK Generation
http://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Modulationhttp://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Signal_(electrical_engineering)http://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Frequencyhttp://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Phase_(waves)http://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Binary_numeral_systemhttp://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Binary_numeral_systemhttp://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Phase_(waves)http://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Frequencyhttp://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Signal_(electrical_engineering)http://localhost/var/www/apps/conversion/tmp/scratch_3/wiki/Modulation


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6.2 Demodulation

Demodulation is done using uA741 in comparator mode. The output swings between +/-15V

for +/- Vsat. The output of comparator gives back the PWM. The circuit diagram o

demodulator is shown in Figure 23.

CIRCUIT DIAGRAM:

Figure 6.2: ASK Demodulation using Comparator


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CHAPTER 7

APPLICATION AND SCOPE


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7.1 APPLICATION

The project can be used in large malls and commercial building where monitoring i

impossible by inspection.

In large area of installation we can easily set it up by use of amplification circuit o

lines.

Safe house monitoring.

Warehouse energy monitoring.

7.2 SPECIAL FEATURE

It is affordable because software to be used can be made on any platform suiting an

operating system.

A personal computer can be designed in such a way that with minimum configuration

can handle the system in unique.

Project itself can be enhanced in such a way that it administers the complete switchin

in applied area.

Low power consumption and easy to maintain and repair.

Once the information is received at computer, it can be transmitted over a lon

distance via internet and can be administered remotely by executives of company.

7.3 SCOPE FOR FUTURE WORK

The project in total can send the power consumption of a switch to computer and hence the

power consumption can be remotely monitored. The transmission media to be used i

telephone cable and it could transmit data over a large distance without significant loss

economically.

It can be further translated into a circuit which administers the power and every household i

remote areas. It can be used for automatic lighting system when the beholders of house o


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company are not home.

A website supporting java platform can be part of centralized power monitoring system. Suc

as Gmail when password is entered it will let to decide which switch to close/open an

when?. So a simple idea can be turned into industry.


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CHAPTER 8

RESULT AND CONCLUSION


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CONCLUSION

In this project work an attempt has been made and succeeded in monitoring powe

consumption remotely via telephone cable. The PC can be designed in such a way that wit

minimum configuration it can handle the system only.

RESULT

Rating of

Complex

Load

(Watt)

Observed

Reading on

PC

Conversion

Constant

Time

(sec)

Energy

Measured

(Watt-Hour)

Time

(sec)

1000 10

2000 10

Table 1: Result


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BIBLIOGRAPHY

References:

David A Bell, Op-Amps and Linear I Cs, Fourth Edition, 2006, Prentice Hall India,New Delhi.

K Sam Shamugham, Digital and Analog Communication, Fourth Edition, 2006,

John Wiley and Sons, New York.

Jan Axelson, Parallel Port Complete, First Edition, Lakeview Research, Madison

(USA).


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Appendix I

SOFTWARE


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a. Pratham v7.0

Pratham v7.0 is installed on PC with windows operating system. This software is mad

in VB 6. It can be used on any port and baud rate. This software uses an active x

control in VB6. It is for mere illustration and test of the circuit. The user friendly and

more compatible version can be made using C. The software is so simple that it can

be made free source. Further it can be used to put a switch on and off thus, creating

powerful tool. The same can be used to communicate data over the internet.

b. Code

FRMMAIN.FRM

Option Explicit

Const Start% = 8

Const HighNibbleSelect% = &H10

Dim DataIn%(0 To 7)

Dim ChannelNumber%

Dim LowNibble%

Dim HighNibble%

Private Sub cmdReadPorts_Click()

Dim EOC%

For ChannelNumber = 0 To 7

'Select the channel.

DataPortWrite BaseAddress, ChannelNumber


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'Pulse Start to begin a conversion.

DataPortWrite BaseAddress, ChannelNumber + Start

DataPortWrite BaseAddress, ChannelNumber

'Wait for EOC

Do

DoEvents

LowNibble = StatusPortRead(BaseAddress)

EOC = BitRead(LowNibble, 6)

Loop Until EOC = 1

'Read the byte in 2 nibbles.

DataPortWrite BaseAddress, ChannelNumber + HighNibbleSelect

HighNibble = StatusPortRead(BaseAddress)

DataIn(ChannelNumber) = MakeByteFromNibbles()

Next ChannelNumber

DisplayResult

End Sub

Private Sub DisplayResult()

For ChannelNumber = 0 To 7

lblADC(ChannelNumber).Caption = Hex$(DataIn(ChannelNumber)) & "h"

Next ChannelNumber

End Sub

Private Sub Form_Load()

StartUp


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End Sub

Private Sub Form_Unload(Cancel%)

ShutDown

End Sub

Private Function MakeByteFromNibbles%()

Dim S0%, S1%, S2%, S3%, S4%, S5%, S6%, S7%

S0 = (LowNibble And 8) \ 8

S1 = (LowNibble And &H10) \ 8

S2 = (LowNibble And &H20) \ 8

S3 = (LowNibble And &H80) \ &H10

S4 = (HighNibble And 8) * 2

S5 = (HighNibble And &H10) * 2

S6 = (HighNibble And &H20) * 2

S7 = HighNibble And &H80

MakeByteFromNibbles = S0 + S1 + S2 + S3 + S4 + S5 + S6 + S7

End Function

Private Sub Frame1_DragDrop(Source As Control, X As Single, Y As Single)

End Sub

Private Sub mnuPort_Click(Index%)

frmSelectPort.Show

End Sub


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Frmnewportaddress.frm

Option Explicit

Private Sub cmdCancel_Click()

frmNewPortAddress.Hide

End Sub

Private Sub cmdOK_Click()

Dim NewPortAddress%

Dim IndexOfNewPort%

Dim Character$

Dim ValidEntry%

ValidEntry = True

IndexOfNewPort = 3

'Read the port address entered by the user.

'If the address is within the accepted range, hide this form,

'enable the port's option button, and display the address.

'If the address is out of range, display a message.

'If the text box is empty, disable the port's option button.

Select Case txtAddressOfNonStandardPort.Text

Case ""

NewPortAddress = 0

Port(IndexOfNewPort).Address = 0


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Port(IndexOfNewPort).PortType = ""

Port(IndexOfNewPort).Enabled = False

frmSelectPort.optPortName(0).Value = True


UpdateLabels

Case Else

NewPortAddress = CInt(Val("&h" & txtAddressOfNonStandardPort.Text))

If NewPortAddress > 0 And NewPortAddress < &H800 Then

Port(IndexOfNewPort).Address = NewPortAddress

Port(IndexOfNewPort).Enabled = True

frmSelectPort.optPortName(IndexOfNewPort).Value = True


UpdateLabels

Else

MsgBox "The port address must be between 0 and 7FFF. Leave the address blank if

there is no port."

End If

End Select

End Sub


Left = (Screen.Width - Width) / 2

Top = (Screen.Height - Height) / 2

End Sub


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Frmselectport.frm

Option Explicit

Private Sub cboEcpMode_Click(Index As Integer)

SetEcpMode (cboEcpMode(Index).ListIndex)

End Sub

Private Sub cmdAddPort_Click()

'Display a text box to enable user to add a port

'at a nonstandard address.

frmNewPortAddress.Show

End Sub

Private Sub cmdFindPorts_Click()

'Test the port at each of the standard addresses,

'and at the non-standard address, if the user has entered one.

Dim Index%

Dim PortExists%

Dim Count%

Index = 0

'First, test address 3BCh

Port(Index).Address = &H3BC

PortExists = TestPort(Index)

'If there is a port at 3BCh, increment the index.


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If Not (Port(Index).Address) = 0 Then

Index = Index + 1

End If

'Test address 378h

Port(Index).Address = &H378


'If the port exists, increment the index.

If Not (Port(Index).Address) = 0 Then

Index = Index + 1

End If

'Test address 278h

Port(Index).Address = &H278


'Disable option buttons of unused LPT ports

For Count = Index + 1 To 2

optPortName(Count).Enabled = False

Port(Count).Enabled = False

Next Count

If Not (Port(3).Address = 0) Then


Else

optPortName(3).Enabled = False

End If

End Sub


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Private Sub cmdOK_Click()

frmSelectPort.Hide

End Sub

Private Sub cmdTestPort_Click()

Dim PortExists%

Dim Index%

'Get the address of the selected port

Index = -1

Do

Index = Index + 1

Loop Until optPortName(Index).Value = True


Select Case PortExists

Case True

MsgBox "Passed: Port " + Hex$(BaseAddress) + "h is " + Port(Index).PortType + ".", 0

"Test Result:"

Case False

MsgBox "Failed port test. ", 0, "Test Result:"

End Select

End Sub


Dim Index%

Left = (Screen.Width - Width) / 2


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Top = (Screen.Height - Height) / 2

'Load the combo boxes with the ECP modes.

For Index = 0 To 3

cboEcpMode(Index).AddItem "SPP (original)"

Next Index

For Index = 0 To 3

cboEcpMode(Index).AddItem "bidirectional"

Next Index

For Index = 0 To 3

cboEcpMode(Index).AddItem "Fast Centronics"

Next Index

For Index = 0 To 3

cboEcpMode(Index).AddItem "ECP"

Next Index

For Index = 0 To 3

cboEcpMode(Index).AddItem "EPP"

Next Index

For Index = 0 To 3

cboEcpMode(Index).AddItem "reserved"

Next Index

For Index = 0 To 3

cboEcpMode(Index).AddItem "reserved"

Next Index

For Index = 0 To 3

cboEcpMode(Index).AddItem "test"


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Next Index

For Index = 0 To 3

cboEcpMode(Index).AddItem "configuration"

Next Index

'Enable the option buttons for existing ports.

For Index = 0 To 3

optPortName(Index).Enabled = Port(Index).Enabled

Next Index

UpdateLabels

End Sub

Private Sub optPortName_Click(Index As Integer)

'Store the address and index of the selected port.

Dim Count%

BaseAddress = Port(Index).Address

IndexOfSelectedPort = Index

EcpDataPortAddress = BaseAddress + &H400

EcrAddress = BaseAddress + &H402

For Count = 0 To 3

cboEcpMode(Count).Enabled = False

Next Count

cboEcpMode(Index).Enabled = True

End Sub

The code above is only VB6 code for Pratham v7.0. The required dlls can be found o

windows website. There are three forms in application as depicted before. Modules can be

added to fulfill the port logic control using microprocessor of PC itself.


45/45


Thanks to,

Texas Instruments and National semiconductors for online support.

Watt-hour meter is original idea from National Data Handbook, Prentice HallUSA, 1993.

Google Images.

Department of Electrical and Electronics Engineering, SIT, Tumkur.

centralized power monitoring system report

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