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    BATCH-02

    UNDER GUIDANCE OFMR.V.VIJAYARAMARAJU

    PROFESSOR, DEPT. OF EEE

    QUASARMETER

    RS-485C0MMUNICA

    TIONCIRCUIT

    PC

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    Contents Introduction

    QUASAR METER

    QUASAR MODBUS DETAILSNI LABVIEW MODBUS

    DESIGN OF RS-485 COMMUNICATION CIRCUIT

    LABVIEW SIMULATION AND RESULTS.

    DSP METER

    CONCLUSION

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    INTRODUCTION Smart metering generally involves the installation of an intelligent meter at

    residential customers , offices etc., and the regular reading , processing and

    feedback of consumption data to the customer.

    The intelligence of the meter is incorporated in the electricity meter whichuses DSP technology.

    Energy meter is an electrical measuring device, which is used to recordElectrical Energy Consumed over a specified period of time in terms ofunits.

    The electricity meter communicates by means of a communication circuitand reads all parameters that measured by a meter.

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    QUASAR METER QUASAR is a 96 x 96 mm , flush mounted , single screen

    multiple parameter display digital panel meter for measuring

    electrical parameters.

    The parameters are displayed over all screens which can be

    scrolled up and down by front panel push buttons.

    The meter is designed with DSP technology.

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    The front panel has one LCD display , 4 PBs and a LED.

    The LED flashes at a rate proportional to the kwh in the feeder.

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    FRONT PANEL PUSH BUTTONS

    There are four Push buttons (PBs) on the front panel to do following functions:

    a) scrolling thro display

    b) min/max/present values selection

    c) reset of min/max values

    d) front panel programming.

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    FUNCTIONS OF FRONT PANEL PUSH BUTTONSDisplay scroll PBS &

    All screens of display can be viewed by pressing

    or PBs of front panel. Pressing & simultaneously will take

    display to auto scroll mode. The display will scroll through allscreens at a fixed rate of 3 secs.

    Max / min values selector PB MODE

    The PB designated as 'MODE is meant to read max/min values.

    Normally latest updated values will be displayed. By pressing thepush button MODE, the display can be switched to Min., Max. orpresent values one after the other. The display will remain in Min &Max modes until the PB is pressed again.

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    Reset push buttonResets the max/min values, except power demand & energies.

    Pressing reset key on front panel clears off all the max./min.

    values except the following parameters.

    a) Power demand max. value can be cleared only in the

    programming mode.

    b) Energy counters can be cleared only in programming mode.

    Programming mode can be entered from front panel by

    pressing simultaneously and Mode keys. Meter restarts

    after coming out of programming mode.

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    QUASAR MODBUS DETAILS

    MODBUS Protocol:

    The RS485 interface uses MODBUS Protocol in RTUmode. Communicating with the meter involvessending commands to the meter for reading andwriting the particular register. The meter can be

    addressed with specific user defined meter address(slave ID) from 1-255.

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    MODBUS DETAILSMODBUS is a serial asynchronous protocol.

    The Modbus protocol does not specify the physical interface.

    The typical physical interfaces are RS-232and RS-485.

    The Interface Module uses the RS-485 interface.

    RS485 interface is available to communicate with the meter.

    The interface is available at the terminals.( refer slide 9)

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    CONTInterface Standard:

    The configuration details to communicate with the meter are

    given below-

    Standard RS485 (half duplex)

    Baud rate Selectable- 9600, 4800 bps Parity Selectable- None, odd or even

    Start bit 1 Stop bit 1

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    There are various things to be considered in this modbus protocal:

    Details of communication interface

    Details of MODBUS protocol

    Exception responses Explanation of various functions

    Memory map

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    CONTPROTOCOL

    The RS485 interface uses MODBUS Protocol in RTU mode.

    Communicating with the meter involves sending commands to

    the meter for reading and writing the particular register.

    The meter can be addressed with specific user defined meter

    address (slave ID) from 1-255.

    MODBUS protocol uses half-duplex communications,regardless of the hardware.

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    NI LABVIEW MODBUS

    The MODBUS protocol follows a client/server(master/slave) architecture where a client will requestdata from the server. The client can also ask the serverto perform some action.

    Serial Implementation In Modbus:

    There are two serial modes that the MODBUSapplication layer can follow: RTU and ASCII.

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    Mod bus library

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    RS-485 COMMUNICATION CIRCUIT In this communication circuit we design a pcb which converts

    quasar meter output to TTL logic (using max485) and

    thereafter converting TTL logic to usb mode (using ft232rl) .

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    MAX-485The MAX485 is low-power transceivers for RS-485 and RS-

    422 communication.

    The IC contains one driver and one receiver. The driver slew

    rates of the MAX485 is not limited, allowing them to transmit

    up to 2.5Mbps.

    These transceivers draw between 120A and 500A of supply

    current when unloaded or fully loaded with disabled drivers.

    All parts operate from a single 5V supply.

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    CONT..Drivers are short-circuit current limited and are protected

    against excessive power dissipation by thermal shutdown

    circuitry that places the driver outputs into a high-impedance

    state.

    The receiver input has a fail-safe feature that guarantees a

    logic-high output if the input is open circuit.

    The MAX485 is designed for half-duplex applications.

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    FEATURES Low Quiescent Current: 300A

    -7V to +12V Common-Mode Input Voltage Range

    Three-State Outputs

    30ns Propagation Delays, 5ns Skew

    Operate from a Single 5V Supply

    Allows up to 32 Transceivers on the Bus

    Data rate: 2.5 Mbps

    Current-Limiting and Thermal Shutdown for Driver OverloadProtection

    The transmitter outputs and receiver inputs are protected to15kV Air ESD

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    APPLICATIONS Low-Power RS-485 Transceivers

    Low-Power RS-422 Transceivers

    Level Translators

    Transceivers for EMI-Sensitive Applications

    Industrial-Control Local Area Networks

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    PIN CONFIGURATION

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    RS-485 COMMUNICATIONWith this option, the meters can be networked and various

    parameters can be monitored on a central PC.

    All parameters will be available via the RS 485 port.

    Set up configuration is also possible through this port.

    Protocol: MODBUS in RTU mode.

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    QUASAR OUTPUT TO TTL LOGICThe chips' data sheets label the non-inverted RS-485 line asline A, and the inverted line as line B.

    An RS-485 receiver must see a voltage difference of just200mVbetween A and B.

    If A is at least 200mV greater than B, the receiver's output is alogic high.

    If B is at least 200mV greater than A, the output is a logic low.

    For differences less than 200mV, the output is undefined.

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    RS-485 TO USB CONVERTER

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    Cont`d When a network needs to transfer small blocks of information

    over long distances, RS-485 is often the interface of choice. Thenetwork nodes can be PCs, microcontrollers, or any devicescapable of asynchronous serial communications.

    An RS-485 network can have as many as 32 unit loads, with oneunit load equivalent to an input impedance of 12k. By usinghigh-impedance receivers, you can have as many as 256 nodes.

    An RS-485 link can extend as far as 4000 ft., and can transferdata at up to 10 Mbps, but not both at the same time. At 90 kbpsthe maximum cable length is 4000 ft; at 1Mbps, it drops to 400ft, and at 10Mbps, to 50 ft. For more nodes or very long distances,

    you can use repeaters that regenerate the signals and begin a newRS-485 line.

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    Cont`d The Each USB-RS485 cable contains a small internal

    electronic circuit board, utilizing the FT232R,which isencapsulated into the USB connector end of the cable. Theother end of the cable is bare, tinned wire ended

    connections by default, but can be customized usingdifferent connectors to support various applications.

    RS232 or RS485 and are compatible with all popularcommercial software programs that support the ModbusRTU protocol.

    The series provide computer monitoring and control ofdevices through solid-state relays or TTL signals. The statusof digital inputs and outputs is communicated to the hostin Modbus RTU

    http://www.ftdichip.com/Products/ICs/FT232R.htmhttp://www.ftdichip.com/Products/ICs/FT232R.htmhttp://www.ftdichip.com/Products/ICs/FT232R.htm
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    FTDI Driver Installation

    Follow the steps below to install driver of USB-High Speed Serial Converter: 1. Power on your computer and make sure that the USB port is enabled and

    working properly. 2. Plug in the USB-High Speed Serial Converter into the USB port, the PC

    should then detect the new hardware, or if not, then run the Add New

    Hardware Wizard to assist you in setting up the new device. 3. If the PC detect the new hardware it ask you to insert the USB-HS Serial

    Converter software driver (FTDI USB driver) into the CD-ROM drive and clicknext to continue. It is also a possible to download the driver from Web sitewww.jvl.dk/download.

    4. Windows will now detect the driver (FTSER2K.SYS). The Path on theCD_ROM is

    D:\Driver\ATC820\For Windows 98&Me \For Windows Vista x 64 \For Windows XP Click Next to continue installation.

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    LABVIEW SIMULATION & OUTPUT

    f

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    from QUASAR meter

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    Uploading to ethernet To create an interactive Excel

    web page that takes advantage

    of Microsoft's Office Web

    Components.

    The spreadsheet web page is created by embedding anExcel XML file in a Html file

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    Excel sheet saved as

    web page

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    CONT

    We don't need to spend money on web design programs.

    Although HTML, the code for making webpages, may lookcomplicated, it's quite easy.

    The only thing needed to make

    a website is a browser and a

    simple word processor suchas notepad.

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    Web Server Once you have a website put together you need a web

    address to go with it.

    Now that you have made your website you require theservices of a web host. Web hosts provide a place onthe internet where folks like you can put a website sothat everyone can see it. This web space is called a "webserver".

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    Uploading Once we have a place for our website

    we need to copy our website files from our

    computer to the web server, either by means of acontrol panel in your web hosting account or by

    a program called ftp.

    This process is referred to as "uploading".

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    FTP

    What is FTP?

    How to Transfer Files from Your Hard Drive to WebSite?

    FTP stands for File Transfer Protocol. There are lotsofFTP software programs available, and they will work

    on similar principles.

    http://www.thewebseye.com/upload-a-web-page.htmhttp://www.thewebseye.com/upload-a-web-page.htm
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    CONTWith each we need the IP address of ourweb host,

    your username and your password.

    There are a number of good free

    FTP programs available. In fact many

    website design programs come with

    in-built FTP "publishing" tools.

    http://www.thewebseye.com/find-a-web-host.htmhttp://www.thewebseye.com/find-a-web-host.htm
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    DSP METER DESIGNING A CIRCUIT FOR GENERATING A

    VOLTAGE LESS THAN OR EQUAL TO 3.3V.

    SIMULATING IT IN MULTISIM.

    DESIGNING OF THE PCB IN EAGLE.

    BLOCK DIAGRAM FOR SENSING VOLTAGE ANDCURRENT SIGNALS

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    CONT DSP circuit is designed so that it can modify the rated

    3-phase voltages and currents (obtained from thesupply 415V, 50Hz) in such a way that they can be

    given to the DSP. The DSP works only with inputs withvalues less than 3V. Also, the signals given as inputs tothe DSP must be entirely positive, i.e., there shouldnot be any zero-crossing in the signal waveform. The

    offset given is then removed using softwareprogramming, i.e., after signals have been acquired bythe DSP.

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    CIRCUIT DIAGRAM & SIMULATION

    RESULTS

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    enera on o v us n sp

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    enera on o . v us n sptechnology.

    oc agram or sens ng vo age

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    oc agram or sens ng vo agesignals

    Pin diagram of LM1458N dual

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    Pin diagram of LM1458N dual

    OpAmp

    o age an curren s gna s a a

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    o age an curren s gna s a aacquisition.

    The 3-phase voltages are first sensed using 230V/3Vpotential transformers and the 3-phase currents byusing 5A/0.038A current transformers. The currents

    thus sensed are converted to voltage signals using a 100ohm resistor in each phase.

    Sinusoidal signals of RMS value 3V are thus obtainedfrom the current and potential transformers. Eachsignal is given to a potential divider made of three 1Kohm resistors connected in series, thus giving a dropof 1V (RMS) across each resistor.

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    CONCLUSION Details about QUASAR intelligent panel meter is studied.

    Interfacing of QUASAR meter with PC using RS-485communication circuit is studied.

    Learnt about MODBUS protocol.

    Connections of block diagram in LabView software.

    Updating the data to WEB page using FTP software.

    Successful Hardware implementation by connectingSchematic and making Board layout in EAGLE .

    Voltage and current data acquisition using the designedpcb.

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    BY BATCH-02

    GAYATRI DEVI B J 08241A0210

    JYOTHSNA Y 0824140214THASLEEMA NASREEN 08241A0251

    SANTOSHI K V 09245A0204


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