COMMUNICATIONSYSTEMFORCONTROLLING - …irep.iium.edu.my/5899/1/01684818.pdfSherozKhan', RafiqulIslam2,Dr Othman 0Khalifa3 Janaluddin Omar4, AbubkarHassan5,IsmailAdam6 1,2 DepartmentofECE,

COMMUNICATION SYSTEM FOR CONTROLLING SMART APPLIANCESUSING POWER LINE COMMUNICATION

Sheroz Khan', Rafiqul Islam2,Dr Othman 0 Khalifa3Janaluddin Omar4, Abubkar Hassan5, Ismail Adam6

1,2 Department ofECE, International Islamic University Malaysia3 4Department ofElectrical Engineering, UNITEN, Malaysia

5Electronics Department, University Kuala Lumpur, Malaysia

AbstractMicrocontroller-based master and slave units are

designed with serial ports for communication with acomputer and a transmission port to couple the signalto modems at both ends. The programming of themicrocontrollers at either end for formatting the databits before they are sent down the power line and thedevelopment of software for putting in place therequired master and slave protocols is presented.

Coupling data signals to power line throughinterfacing circuits is a challenging task as power lineand the communication system operate at two extremes- very lowfrequency and high powerfor thepower linewhile communication is working at very highfrequencyand very low voltage and current levels. Hence, thecoupling circuit to be designed must be capable towithstand the high power system side in order toprevent a damage being done to the electronic side ofthe communication system. At the same time it must bereliable enough to make sure that data bits aretransferred on to the power line with high accuracy.The interfacing circuits are designed and tuned tofrequency contents making the bits of data. Thefrequency performance of these coupling circuits ispresented, showing the range a power line can be usedfor communication ofsuch data.

1. INTRODUCTIONThe use of the power line communication

networks has attracted much attention and has becomea mature subject of research in the last few years.Power Line telecommunications is a rapidly evolvingtechnology, aiming at the utilization of the electricitypower lines for the transmission of data [1]. Thus, theemerging PLT technology opens up new opportunitiesfor the mass provision of local access at a reasonablecost. In addition, PLT can provide a multitude of newservices to the users which are difficult to implementby other technologies including SCADA (e.g., remoteelectricity meter reading, appliance control andmaintenance, energy management,) and large scaleapplications for home automation [2-4].

Some of the problem areas are challengingsuch as unpredictability of connected loads, Frequencyand time dependence of impedance, attenuation andtransmission characteristics; impulse and backgroundnoise and their wide variability; limited bandwidth;harmonic Interference. These issues have beenaddressed in the forn of modeling power before usingit as a reliable communication medium [5-7]. Thecommunication potential of power line communicationhas been properly explored for the application ofcondition monitoring of electric motors [8].

The work in this paper is mainly designed forthe purpose of controlling electric appliances inpremises such flood light control of golf courses or thecontrol of high power lights on highways. The sendingmaster and receiving end slaves modules are designed,properly coupling circuits are developed, and thesoftware both fro the master and slave is written usingC programming language with the help of a microchipdebugger.

2. OVERALL BLOCK DIAGRAMSYSTEM OVERVIEW

The master that having the display unit (LCD)and input console (board) is coupled to power line atthe sending end for sending data to the slaves devicesat other ends of the power line (Fig. 1). The master hasthe features to encode, modulate the commands beforethey are sent down the power line, while the slave hasbeen designed to demodulate and decode thecommands received from the power line.

In the case of a wrong command being keyedin, the master prompts the user. The modulated signalcontains start bits, control bits, address bits and stop bitfor system control and identification. If the signaldetected is for the specific slave device, the slavedecodes the control bit appended to the signal andresults into the appropriate action accordingly.

The system has been developed for workingwith a maximum number of eight slave devices insimplex mode. Hence, the protocol and algorithmdeveloped were developed to suit such application only.

The microcontroller is used to handle theinput from the key board, display the data on the LCD,

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read the data displayed on the LCD, analyze the dataon the LCD and produce the appropriate serial data tobe fed into the PLDC modem. The single phase couplerpasses only the modulated signal into the power lineand protects the modem from the enormous power lineover shoot voltages. The darken line from microcontroller to the PLDC modem and from PLDCmodem to single phase coupler marked the direction ofthe signal from the microcontroller. Even the data isnot received in other direction but, it has beenconnected appropriately for future work.

Similarly a more detailed block diagram forthe slave devices is shown in Fig. 2. The microcontroller is programmed to detect and decode the datasignal (data out) received from MODEM and drive theLED's array accordingly.

Again, there is single phase coupler whichallows the signal of interest to pass and attenuateanother signal including that of the power line voltage.The darken line from the single phase coupler into thePLDC modem and from PLDC modem to themicrocontroller shows the direction of the signal. Theconnection for data to be transmitted in other directionhas been spared for future work.

The schematic for the master is presented inFig. 3, where power unit obtained form the mainsprovides dc for the MODEM, LCD, microcontrollerand keyboard. The modulated signal from theMODEM is serially tapped in to the power line via thesingle phase coupler which passes to the slave devicesvia the power line. Figure 4 shows the circuit diagramof the slave device. The modulated signal is fed intothe PLDC modem via the single phase coupler and asmall signal amplifier is used to amplify the receivedmodulated signal attenuated while traveling down theline. Figure 5 shows the circuit diagram of three phasecoupler which provides an interfacing between thedifferent phases by allowing only the modulated signalto passes across the different phases.

4. COMMUNICATION REGIME

The reliability of any data transmission isinfluenced substantially by modulation and codingschemes, as the sensibility against disturbances andnoise pickup could be reduced significantly by efficientmodulation procedures, error correction codes andcheck sums. Figure 6 shows that the transmit dataconsists of the start bit, on/off bit, devices/ pointsaddress, slave devices address, select bit, parity bit andstop bit.

The start and stop bits were used forsynchronization of the data. They ensure the datatransmit has to be detected in a frame. The stop bitinforms the slave devices the status of the frame. If it isnot detected, then the data has overrun error. The paritybit is included to ensure there is no enter symboldetection occurred in the data transmitted. The sites areidentifiable with the help of a 3-bit address code, with000 through 111 means SITEO through SITE7.

Similarly after the salve address the next 3-bits aresued to identify one of the eight devices.

At idle the data line is pulled up, once it ispulled down the transmission started. Then, theappropriate data for specific command will be sentfollows the format discussed above. The data is fed tothe PLDC modem by appending the start bit, parity andthe stop bit to the data. The corresponding bits of someof the commands are detailed in Figure 7.

Using the interrupt capability of the controller,the start bit can be detected by the microcontroller ofthe slave devices. Once the start bit detected, the slavewill test again the start bit at the 2/3 of the data pulsewidth to ensure the right timing on the data detectionand to get rid of the bouncing effect of the line. If thestart bit is detected successfully, the slave will read allthe data transmitted and the parity bit referred to thedata pulse width. The parity and the stop bit will bechecked by the slave. If any one of them failed, all thedata will be ignored. The experiment has been set up asshown in Figure 8 below. The three phase system iscontrolled by switching on and off the three phaseisolator.

6. RESULTS AND CONCLUSION

The system is designed to work as expectedand has been tested to be showing good response in anoise free environment. The device identity codes sentdown the line are properly received and identified bytheir respective slaves and devices. Also, the slaves actto result into appropriate action on the devicesconnected to the slaves concerned. However, thecircuit shows picking up noise in environment withloads such as exhaust fans, air conditioners and floodlamps. Hence, in the ongoing work, the filter circuitsare to be made altered to have high selectivity, whichcan be improved by increasing the order of the filter(coupler) or replacing the passive by an active filter.

AcknowledgementFinancial support by the Ministry Of Science

and Technology (MOSTE), Malaysia in the form ofIRPA Project No: 03-02-08-0307-EA003 is gratefullyacknowledged.

References

[1] "Power Line Telecommunications Report ontrnamsission of data over the electricity powerlines," prepared by Hans Akkermans (AKMC,The Netherlands), David Healey (Spectrum,United Kingdom), and Hans Ottosson(EnerSearch, Sweden), 1998

[2] A. Treytl, T. Sauter, G. Bumiller. "Real-timeenergy management over power-lines andInternet"; Proceedings of the 8th InternationalSymposium on Power-Line Communications and

0-7803-9521-2/06/$20.00 §2006 IEEE. 2,36

its Applications, vol. ISPLC'04 no. 8, March2004, pp. 306-411.

[3] G. Pratl, M. Lobashov. "Remote Access toPower-Line Networked Nodes: Digging theTunnel"; WFCS 2004 5th InternationalWorkshop on Factory Communication Systems,Vienna, Austria; Sept. 2004; p. 323-326.

[4] M. Lobashov, G. Pratl, T. Sauter, "Implicationsof Power-line Communication on DistributedData Acquisition and Control System", IEEEConference on Emerging Technologies andFactory Automation, Lisbon, Portugal, 2003.

[5] Bilal O., et., "Design of Broadband CouplingCircuits for Power line Communication," 7thISPLC Proceedings, April 2004.

[6] Manfred Z., Klaus D., "Analysis and Modelingof Impulsive Noise on in Broadband Power LineCommunications," IEEE Trans. ElectromagneticCompatibility, Vol. 44, pp. 249-258, February2002.

[7] T.C. Banwell, S. Galli, " A New Approach tothe Modeling of the Transfer Function of thePower Line Channel", IEEE InternationalSymposium on Power Line Communicationsand its Applications, ISPLC'01, Malo, Sweden,April -6, 2001.

[8] Jero A., "Applicability of Power lineCommunications to data transfer of On-lineCondition Monitoring of Electrical Drives,"Doctoral Thesis, Lappeenranta University ofTechnology, ISBN 951-764-783-2.

Fig. 1: Block Diagram of the Master Device

Fig. 2: Block Diagram of the Slave Device

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FIGURE 3: Circuit Diagram of the Master Device

Fig. 4: Circuit Diagram of the Slave Device

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N EUTRtALHO L E-SKBM

7 7N

Fig. 5: Circuit Diagram of the Three Phase Coupler

Fig. 6: Data Transmit and Receive Format and Checking Protocol

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YELLOW F2 02 L2

HO LE-SKE F U 22 Mo2 tl F tl H

BLUE F3 03 L3 TR1

On/off bit Point add Slave add Select bit

STA BO Bi B2 B3 B4 B5 B6 B7 PAR STO

RIT BBT T

Data Transmit Format

On/off bit Point add Slave add Select bit

I STA BO Bi B2 B3 B4 B5 B6 B7 PAR STO

IDL t p IDLData Receive Format and Checkingprotoc BIT

Data Receive Format and Checking protocol

i

2699

COMMANDS DATA

a o01 101 11110110

ai f f01 101 11011 011

S X f ' f11000-111 11000-ill 1101

s X a I IonIx I 0 n ~~~~~~~~~~~~~011000-ill 1010 11 0

s X a I I f f0 11000 -ill 11010 11 1

X CAN BE 0 TO 7Y CAN BE 0 TO 7WHEREX IS THE ADDRESS OF THE DISTRIBUTED POINTS ALLONG THE POWER LINE NETWORK ANDY IS THE ADDRESS OF SWITCHES IN THE SPECIFIC POINT

Fig. 7: Commands and Transmit Data Relationship

/ SLAW THREE PHAJE DISTRIBUTION BOARD

MASTER THREE PASE COUPLER

Fig. 8: Experimental Setup of Overall System

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