Habitat for Humanity by iPn59C

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									  Habitat for Humanity
                EPICS
    Progress Report Spring 2002
            Feb 19th, 2002




           Project partner:
         Habitat for Humanity
        420 South First Street
         Lafayette, IN 47901
              423-4590




Rachel D. Austin      austinr@purdue.edu
      Mike Schilz     schilzm@purdue.edu
Marlana McClain       mmcclain@purdue.edu
Virginia Christian    vfoy@purdue.edu
   Berook Moges       moges@purdue.edu
Vijay Murugesan       vmuruges@purdue.edu
 Jimmy Johnson        johnso29@purdue.edu
     Doug Crook       dcrook@purdue.edu
 Chris Costanzo       costancj@purdue.edu
  Anshul Mangal       amangal@purdue.edu
        Erin May      maye@purdue.edu
     Matt Selvey      selvey@purdue.edu
Executive Summary
       Habitat for Humanity International and their local city affiliates work to provide
quality, affordable homes to low-income families. The final cost of the home is based
upon the material costs and the quality of the techniques used in construction.
According to the Habitat for Humanity International website, www.habitat.org, low-
income homeowners pay proportionally more of their salaries for utilities and rent than
homeowners in middle or upper class.
       The EPICS program has been working with Habitat for Humanity for several
years to assist Habitat in improving their quality of service, reducing the costs of the
houses and making them more energy efficient. The current EPICS Habitat for
Humanity Team functions as three main sub-teams; the D-base team, the Solar team
and the Home and Energy Analysis Team (H.E.A.T.).
       The main goals of the H.E.A.T. are to inform Habitat homeowners of potential
energy savings and to implement new ideas to further save money. Setback
thermostats, home efficiency guides, and identifying substandard housing are various
projects that contribute to the overall goal of Habitat for Humanity.
       The D-Base team this semester is working primarily on coding and
implementation of the database. This database will be located in the resale store and
run off a personal computer.
       The Solar team is currently in the process of constructing a solar powered attic
fan that will lead to lower cooling bills in the summer and keep houses cooler. This
project is proposed to be in testing stages by the end of the semester.
       As the semester continues progress is being made in all areas. The teams are
focused on the tasks at hand and are concentrating on reaching the goals set at the
beginning of the semester. All three teams are working towards our main goal of
making a Habitat home more energy efficient, more economical and of better quality.




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                         Table of Contents
                                                               Page
Executive Summary……………...…………………………………..……..………………1

Project Tasks……………..……………………………………………...….……………….3

      SOLAR……...…………………………………………………….……………….3

      D-Base………………….………………………………………....………………6

      HEAT……………………………………………………………..……………….9

Project Planning…………………………………………………………………………….13

      Team Continuity Plans…………………………………………...………………13

      Expected Semester Outcomes……………………………………..…………..14

      Team   Organization……………………………………………………….………14

Appendix A: Solar Team Design Details………….……..………………………………15

Appendix B: Point Of Sales Database Design Details.…………………………………20




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Project Tasks


Solar Team
       The Solar team’s tasks this semester consist of the continuation of the design
and construction of a solar attic fan. In the previous semester, we successfully
designed a model of the attic fan. We are currently working out the bugs in the various
components and completing the testing phase. We have also come up with many ideas
on how to mount the fan on top of the roof. This semester, we will implement one of the
plans and mount the fan on the roof of the resale store. We will also collect data and
make conclusions.


Solar Powered Attic Fan
       The purpose of our solar powered fan project is to implement a cost effective and
low maintenance way to provide air circulation in a Habitat for Humanity home. Low air
circulation is a problem because during the summer, a typical attic can reach
temperatures in excess of 150 degrees Fahrenheit. At such a high temperature, the
attic acts as an additional heating source. In homes with air conditioners, this added
heat would add an extra cooling load and lead to the energy bills. In homes without air
conditioners, the air temperature in the house would be approximately 10 degrees
warmer than a house with a properly ventilated attic (www.attic-fan.com).
       With the task at hand being to properly ventilate the attic, we have decided to use
solar power for our fan because of the direct correlation between high attic
temperatures and direct overhead sun. In essence at the peak hours of heat (when the
fan is needed most) the potential for collecting solar power is at it’s highest. With the
possibility of lower than adequate sunlight to keep the fan running at other times, a
battery will be in place to store the solar power and keep supplying continuous power to
the fan. With this basic combination of solar cell and battery, our goal is to be able to
keep the temperature of the attic at the temperature of the outside air.
       All members of the solar team are working on this project, including:
       Matt Selvey
       Anshul Mangal


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      Mike Schilz
      Vijay Murugesan
      Lafayette Habitat for Humanity has worked in conjunction with us on this project
and also on the previous form of this project. The previous solar powered attic fan was
not installed due to incorrect analysis and project approach as shown below. Because
of previous work on this project, our project partner has been an asset to our team
because they can give us reasons why the other project failed and what we can do to
ensure success of this project.
      The previous solar powered fan project was started in the fall of 1996 and the
final proposal was given in the fall of 1998. Because of the adolescent stages of solar
power at that time, solar panels were more expensive and not as efficient as those that
meet today’s standards. The previous team’s analyses led them to purchase a 75W
solar panel, a charge controller, deep cycle battery (12V), AC/DC inverter and an 8”
inch AC fan. Their setup configuration is shown below:




     Solar Panel
       75 W                Charge
                          Controller     12 V       AC/DC             Fan
                                        Battery     Inverter

                         Figure 1: Previous solar powered fan design
      Figure 1 shows a solar cell used to generate power at 12VDC and supply the
charge controller. The charge controller regulates the charging of the battery. It makes
sure the battery is not over or under charged. After the power goes through the charge
controller, it charges the battery. The battery then feeds into the AC/DC converter. The
AC/DC converter is necessary because the fan operates on alternating current power
and the battery output is direct current. After the AC/DC conversion, the power is



                                                                                          4
supplied to the fan at a continuous 120VAC. The final results show the successful
running of this solar fan configuration. The solar fan was able to successfully cool the
attic, but the problem was the cost. Because cost is a big concern of Habitat for
Humanity, the cost efficiency of the design is of essence. With a total cost of over $700,
the project was not expected to save the homeowner money in a reasonable amount of
time.
        There are many reasons why we have been able to cut costs on this project.
First, the cost of solar panels and other various supply costs have decreased over the
past three years. Second, solar panels are more efficient in design and can produce
more power per square inch of solar panel. Third, we expect to be able to use smaller
(< 225 W) solar cells than initially designed because of the implementation of a tracking
system. We also will design and build our own charge controller, which will save
money. Last, there are many areas of the previous project that caused power loss and
are not needed. The biggest loss of power was incurred during the DC to AC
conversion, which we solved by using a DC, rather than an AC, fan.
        The following analysis justifies our solar powered fan revision. We are using the
same basic concept as the original solar fan, but will take care of the problems
discussed previously. We will begin our changes with the fan. As discussed previously,
we are using a DC powered fan that provides 500 CFM. This fan motor will allow
fluctuations in the voltage coming from the battery (the fan will work between 10-16V
DC). With an all DC power system, we will not need an AC/DC converter. The only
trade off to a DC fan is that it is about 40-50 dollars more expensive than the AC fan.
However, if the price of the AC/DC converter plus the AC fan is compared to the price of
the DC fan by itself, the DC fan is slightly cheaper. Other than modifications to the fan,
we also changed the size and power of the solar panel. After researching various
market products and the energy needs of our DC fan, we concluded that we can use a
solar panel that supplies a max power of 10W. The previous project consisted of three
75W solar panels. Our panel is 15” by 10” instead of the previous 3’ by 4’ panel. The
final differences in our system is a charge controller and tracking mechanism, allowing
maximum sun exposure to the solar panel at peak times of the day. In the past, a




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charge controller was purchased, but we designed and built our own to save money.
The total cost estimate breakdown of our system is as follows:


                         Solar Panel                        $90
                         Battery                            $50
                         DC Fan                           $110
                         Tracking System                    $25
                         Charge Controller                   $5
                         Miscellaneous Items                $20
                                                   Total $300


      Last semester, the technical progress that was made included determining the
amount of power that is needed from the solar panel to power the fan. We also made
various design drawings of how the solar panel will connect to the rest of the system.
Additionally, we worked on various design issues, including preliminary designs for a
charge controller and for the actual tracking system. This semester, design work has
been concluded on the orientation and settings of both the sensors and the logic behind
the tracking device, and the charge controller is fully functional. Simple issues remain,
such as mounting the fan on the roof and minor debugging of the charge controller and
tracking system.


Data Base Team
      The D-Base Team’s objectives this semester included the continuation and
completion of the resale store database project. The database involved designing a
bar-coding system and updating its interface and content according to HFH’s feedback
on the prototype delivered this semester. The access database interface with visual
basic will be completed by the end of this semester.


Home Construction Guide
      The Home Construction Guide (HCG) pages were designed to assist those who
are involved with the construction process. Specifically, the HCG contains a


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construction timeline, volunteer tutorials, and a materials list for each floor plan. The
construction timeline was created to serve as a resource for construction members. It is
set as a standard 10-week build for Habitat for Humanity of Lafayette. A section is
highlighted to show the days in which work should be done and completed for a specific
task. Also, many of the tasks listed have links to volunteer tutorials. The volunteer
tutorials are divided into multiple sections based on their order in the home building
process. Each tutorial guides the reader through a step-by-step process for completing
the task. Included in each tutorial are an equipment list and a brief outline of the
process. Last semester, Renae Hopf enhanced and modified the tutorials, which are
equipped with diagrams, digital photographs, and video taken from building sites during
construction. The main goal of this project was to improve the effectiveness of the
tutorials in preparing the volunteers before they reach the worksite. The team had
received negative feedback from the Purdue University chapter of Habitat for Humanity
from the previous semester, and this led to adding multimedia tools to the tutorials.
Also, at the request of Doug Taylor, Executive Director of Lafayette HFH, the tutorials
have been simplified and made more concise so that they may be as effective as
possible. The different tasks outlined by the current tutorials were re-evaluated and
replaced with more desirable ones. This section of the HCG will undergo many
revisions over time according to future feedback received from Habitat for Humanity of
Lafayette and its volunteers. The Blitz Build that took place last semester was a
valuable source for the multimedia additions and for a better-defined set of jobs that the
volunteers usually participate in.


Database Project
       The resale store database project will be enhanced with a bar coding system and
any necessary updates to the internal structure of the product database. The bar
coding system will include a login and verification portion that accesses a separate
database filled with user information. The product database interface section will accept
the user’s requests to the product database and process them accordingly.
       The first implementation of the database is currently being evaluated by Habitat
for Humanity. Jimmy Johnson has taken a PC with the access database on it for



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Habitat to test and evaluate. Based on Habitat’s feedback, changes are expected.
Currently, the D-Base team is working on interfacing the Access database with Visual
Basic (VB), giving VB all control. This would eliminate some security concerns. The D-
Base team has also decided to change the layout of the application for aesthetic
purposes and for easier navigation through the user interface. The D-Base team has
adapted a tab look for the form. This idea is credited to Chris Costanzo. The layout
form will have 4 tabs. The first tab is the “View” tab. This feature is being designed by
Berook Moges. This tab will have four options, which will display all products, all
product types, all donors or all invoices. The second tab, which is also designed by
Berook, allows the user to search all fields either manually or using a bar-code scanner.
The third tab, which is the “Add” tab, is being designed by Chris Costanzo. This feature
will allow a user to add new information to the database. The fourth tab is the “Delete”
tab. This feature is restricted to only the administrator thereby providing security to the
database. Jimmy Johnson is designing this feature. Erin May is working on changing
the login format. For the sake of uniformity, the team has decided to change the format
from last semester. Erin May will also improve the user interface of the access
database, time permitting.
       The bar coding system will employ a cordless hand held CCD (Charge Coupled
Device) to allow unrestricted movement through the resale store while using the
database. This system will speed the operations of the store by adding simplicity to the
database interface. Instead of added bookkeeping and tedious typing of product ID’s
and other information, the bar coding system will introduce a “scan-and-go” aspect to
the resale store’s operation. The system’s design will be conducted using Visual Basic
because of its advanced Access database interfacing capabilities and its availability.
The feedback that Habitat provides over the next few semesters will determine where
the interface and the database internals are headed. Regardless, these tasks will be
completed using normal Microsoft Access wizards, SQL, and Visual Basic. The
database will be upgraded so that reports may be generated for product lists, records,
and audit information. The interface menu will be changed to fit whatever is needed to
achieve maximum understanding and usefulness by the volunteers at the resale store.




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H.E.A.T. (Home and Energy Analysis Team)
       International Habitat for Humanity works to provide quality, affordable homes to
low-income families. The final cost of the home is based upon the materials and the
quality of the techniques used in construction. The goal of the Guide to Energy Efficient
Construction (GEEC) sub-group is to create an educational manual to inform Habitat for
Humanity volunteers and staff of energy efficient construction techniques and designs.
The idea was submitted by the project partner point of contact Doug Taylor, who
expressed interest in a manual that could incorporate simple ways for volunteers to
make homes more energy efficient. The guide will include these techniques, as well as
energy efficient design recommendations from previous EPICS groups’ results.
       Habitat for Humanity International has enacted the 21st Century Challenge which
helps communities develop a feasible plan to eliminate substandard housing in their
area. The first step to achieving that goal is to develop a procedure to identify
substandard housing. The intent of the substandard housing project is to define a
process for identifying substandard housing and document the results.


Guide to Energy Efficient Construction (GEEC)
       The intended audience of the GEEC is not the ordinary volunteer, but the site
coordinator who directs the home construction and the local affiliate staff who make
decisions for home construction design.
       The GEEC will be broken into 2 parts: energy efficient construction techniques
and design recommendations. The construction techniques section entails methods
used by volunteers during the construction phase that will decrease heat and air
leakage out of the home. Such measures include installing fiberglass insulation around
windows, sealing joints, decreasing the leakage around dryer vents as well as other
energy saving techniques. The second portion of the guide will be devoted to design
guidelines that reduce energy use and including central air conditioning, setback
thermostats, and other recommendations made by previous EPICS Habitat for
Humanity groups.
       The GEEC sub-group already has research done by Energy Team groups of
previous semesters. The manual provides a way to publicize and distribute those


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results. Before the results are distributed in this format, the output from the building
energy simulation tool (Energy 10) must be verified. Results from the Energy 10
simulation tool will be compared to real world energy use as well as another energy
simulation modeling package.


Energy 10 Issues
       Energy 10 was inoperative at the beginning of the semester. This is a problem
that is faced from time to time, but has never been fully addressed or documented.
There are two issues: accessing the materials library on the EPICS software lab
computers and running HFH house models from previous semesters with HFH specific
plans and materials.
       When Energy 10 is installed on computers in the EPICS software lab, the
materials library is not accessible due to restricted computer access privileges for
students. In previous semesters, this was fixed by making the materials library globally
accessible. This was not a feasible solution this semester, so lab managers Nick
Fellicelli and Jason Sherman gave students “power user” access on the two computers
with Energy 10 installed on them. This allows everyone to access the material library
files. When Energy 10 is installed on new computers, this issue will have to be
addressed.
       The Habitat for Humanity house plan models in the Energy 10 program contain
specific inputs not found in the provided software package. For example, several of the
houses have windows that are not found in the set of predefined window types. When
the file is opened, an error is produced. In order to make Energy 10 work correctly,
these materials must be entered into the program.


Energy 10 Verification
       Research was conducted on Energy 10 and other energy analysis packages on
the Internet. The accuracy of Energy 10 had been demonstrated using BESTEST, a
verification process adopted by the Department of Energy. Other energy analysis
packages we researched were DOE-2 and Energy Plus.           Next, we began putting
together a spreadsheet that compares Energy-10 data obtained from simulations



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conducted in 1999 on Habitat houses with actual gas and electricity bills from those
houses. We are still working on this spreadsheet.


Energy Efficient Construction Research
       Research will be conducted to find ways to incorporate energy efficient
techniques in the construction phase. Doug Taylor suggested some procedures, such
as insulation installation, which will be added to the manual. The Internet and local
libraries will be consulted for further information. In addition, John Sears, from the
Lafayette Habitat for Humanity chapter, attended a conference for the Green Team in
Denver, CO, last year. His knowledge and resources will be utilized as well.
       After the information is assembled, the exact layout will be designed based on
the available data as well as other similar guides.




Substandard Housing
Our approach to completing this project consists of eight objectives. The current status
of these objectives is indicated in parenthesis.
   1. Meet with project partner and define exact parameters of study. (completed- met
       with Don Biddle of HFH Lafayette 2/12/02)
   2. Review documentation completed by freshman engineering class (completed).
   3. Identify housing rated C and/or D by freshman class (completed).
   4. Define rating system for foundation, exterior walls &windows, landscaping,
       roofing and overall appearance (in progress).
   5. Define documentation process (in progress).
   6. Acquire data (not started).
   7. Complete Prospect File (not started).
   8. Present results (pending).




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Objective 1
The HEAT Team met with Don Biddle, procurement manager of HFH Lafayette, on
February 12, 2002 to discuss what results from this project would be the most beneficial
for HFH. The following results were identified from the meeting:
      To formulate an in depth rating system for housing rated C and or D by freshman
       class.
      To complete a Prospect File for each housing unit rated C and or D by freshman
       class.
A Prospect File is a form for HFH that lists information about potential construction sites.
Included on the form is the name of the property owner, address, key number, existing
liens, and zoning among other information. All this information can be found through
public records.


Objective 2
The Substandard Housing Team has obtained and reviewed the documented results
obtained by the freshman class.


Objective 3
The Substandard Housing Team has sorted through the documentation in order to
separate the houses rated C and/or D by the freshmen class. The housing rated C
and/or D will be the focus of our project.


Objective 4
The Substandard Housing Team has done research via the Internet for existing housing
regulations. By researching these regulations, a rating system for foundation, exterior
walls and windows, landscaping, roofing and overall appearance will be determined.
Some sources found are http://www.hud.gov,
http://www.fedstats.gov/qf/states/18/18157.html, http://www.habitat.org/build/21st/.


Objective 5
The Substandard Housing Team has not yet identified the documentation process.


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Objective 6
No data have been taken.


Objective 7
No Prospect Files have been completed


Objective 8
No results to report.


Project Planning


Team timeline
Week 1-2: Orientation and meeting with project partner
Week 3-4: Beginning of projects and team integrations
Week 5-6: Continuation of projects in individual groups and preparing for midsemester
reports and poster.
Week 7: Midsemester report due and poster due
Week 8: Alternative meeting for in lab meeting?
Week 10-11: install projects that are being tested
Week 12: Finishing up work for semester and delivering other projects
Week 13-14: Test projects and prepare for final presentation


Team Continuity Plan
Our team’s continuity plan consists of keeping everyone in the sub-team well informed
of what is going on in each dimension of the group. This leads to complete knowledge
about all aspects of the design. Therefore when one group member is not present, or
leaves after the semester, the rest of the group can continue with the project. Also,
complete documentation and thorough reports are always up kept in the chance of no
returning members.




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Expected Semester Outcomes
Solar: Implementation of the completed prototype of the solar powered attic fan.
Beginning of testing of the unit once installed on Habitat roof.


D-Base: Completion of the Database coding and install in the resale store.


HEAT: Completion of Setback thermostat study, thorough start on the GEEC and
substandard housing.


Team Organization

HEAT Team:

      Rachel Austin - Team Leader
      Doug Crook
      Virginia Christian
      Marlana McClain
D-Base Team

      Berook Moges - Team Leader
      Jimmy Johnson
      Erin May
      Chris Costanzo
Solar Team

      Anshul Mangol - Team Leader
      Matthew Selvey
      Mike Schilz
      Vijay Murugesan
Overall Team Leader: Matthew Selvey

ESAC Representative: Rachel Austin



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Webmaster: Chris Costanzo

Liason: Doug Crook

Key Keepers: Jimmy Johnson, Matthew Selvey




Appendix A: Solar Team Design Details



Charge Controller for Solar Powered Attic Fan
Specifications
Night-time current drain: 0.6 mA
Operational current drain: 19 mA
Maximum solar panel current: 3-10 Amps
Voltage drop during charging: 0.5 Volts at 1 Amp


Parts List
U1           1458 dual op-amp
U2           741 op-amp
U3           4011 CMOS quad nand gate IC
U4           78L05 or 7805 voltage regulator IC
Q1           IRFZ34 power MOSFET
Q2           2N3906 PNP silicon transistor
D1           80SQ045, or MBR1045GI Schottky
             diode
D2           Red LED
D3           Green LED
D5-D7        1N4148 silicon switching diode
C1-C8,
C21,C23 0.1uF ceramic disc capacitor
C9           0.001uF ceramic disc capacitor


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C20        100uF 16V electrolytic capacitor
R1-R3,
R7         100KOhm 1/4w resistor
R4         39KOhm 1/4w resistor
R6, R10    2.2KOhm 1/4w resistor
R8         47KOhm 1/4w resistor
R9         1MOhm 1/4w resistor
R11-R13 100K potentiometer
F1         DC fast blow fuse
L2         ferrite bead on a 22KOhm 1/4w
           resistor




Theory Behind The Charge Controller
       During charging, current flows from the solar panel through diode D1, transistor
Q1, fuse F1, and into the battery. Q1 is the main switching device in the circuit. When
the battery is in need of charging and power is available from the solar panel, the
charge controller connects the solar panel to the battery. Diode D1 is a Schottky device
and prevents back currents from flowing from the battery to the solar panel. Fuse F1
provides a safety device in the event of a short.
       Comparator U2 is used to control power to the rest of the circuit. When battery
voltage is greater than solar panel voltage, for example at night, the rest of the circuit is
disabled. When the battery voltage is less than the solar panel voltage, the transistor
Q2 is switched on and the rest of the circuit has power.
       Comparators U1A and U1B monitor the battery voltage and switch states when
the battery is fully charged or needs charging. There is a flip flop circuit consisting of
U3A and U3D whose output drives two LEDs used to indicate battery charging or fully
charged.
       There is also an equalizing switch, which allows for an occasional over-charge of
the battery. Equalizing is designed to bring lower voltage cells in the battery up to a full
charge.


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*Specific components are shown in the circuit diagram labeled Figure 2




                        Figure 2 – Charge Controller Circuit Diagram


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Solar Powered Fan Tracking System
The purpose of the tracking mechanism is to optimize the amount of power that the
solar panel is able to create.   This will allow cost savings due to a smaller surface area
of solar panel actually used. Various websites for single axis tracking systems claim
power gains between 40% and 300%. This is based on maximizing the direct sun
exposure to the panel to nearly 8 hours instead of the regular 4.


There are 4 main parts to the tracking mechanism.
          1)     The first converts a small voltage gain that an LED senses into a
                 voltage capable of “tripping” relays:




                                         Figure 3A
2)     Below is a diagram showing the locations of the 6 sensors that will be “detecting”
the location of the sun in the sky. The dashed line represents the axis for which the
panel will be rotating about.


                     A1                                  A2


                     B1                                  B2


                     C1                                  C2
                                         Figure 3B
In this step a summing amplifier will be used to sum A1 with A2, B1 with B2, and C1
with C2. This summing amplifier circuit is shown below:




                                                                                         18
            A1
                                                  V(A)
           A2




                                        Figure 3C
3)     The next step is to compare the voltages that are coming in from these “three”
sensors. The purpose of this is so that when the sensors that are directly on the axis of
rotation (center) are not the highest, then the panel will rotate towards the highest
sensed voltage.


Figure 3D shows a circuit using a basic 741 Op Amp.


           V(A)


           V(B)
                                        Figure 3D
Likewise there is a similar circuit for comparing V(B) and V(C). Whenever either V(A) or
V(C) is greater than V(B) the output V(D1) or V(D2), respectively, becomes high.


4)     Finally, the voltages from V(D1) and V(D2) are connected to relays. These
relays both connect to the same motor. One relay, when tripped, sends a positive
signal to the motor, and the other sends a negative signal, depending on the orientation
of the motor and the respective sensors output.




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Appendix B: Point of Sales Database Design Details


Microsoft Access Database
   The point of sales database contains five tables. The first table, “Donor,” will hold all
    the relevant donor information. The second table, “Invoice,” will contain information
    about sales made at the resale store. The third table, “Product,” will hold detailed
    information about the products in the resale store. The fourth table, “ProductType,”
    will hold product descriptions. Finally, the last table, “SoldItem,” will contain
    information about products sold at the store. The schema is given below.
   Schema
       Table Donor
                  DonorID
                  FirstName
                  LastName
                  Line1 (Address)
                  Line2 (extra line for address)
                  City
                  State
                  Zipcode
                  Phone
           Primary Key (DonorID)
       Table Invoice
                  InvoiceNum
                  Date
                  Total Sale
           Primary Key (InvoiceNum)
       Table Product
                  ProdID
                  ProdType (foreign key)
                  DonorID (foreign key)



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                  ProdDesc
                  ProdPrice
                  ProdCond
           Primary Key (ProdID)
       Table ProductType
                  ProdType
                  TypeDesc
           Primary Key (ProdType)
       Table SoldItem
                  ProdID
                  InvoiceNum (foreign key)
           Primary Key (ProdID)

   There are Queries in the database. Queries are searches given specific parameters
    that are used on the database. The different queries that can be made are
    “AllDonors,” “AllInvoices,” “AllProdTypes,” “AllProducts,” “SearchDate,”
    “SearchDonorID,” “SearchInvoiceNum,” “SearchProdID,” and “SearchProdType.”



   There are forms that the resale store can complete to add information into the
    database. The different forms are “AddDonor,” “AddInvoice,” “AddProduct,”
    “AddProductType,” and “AddSoldItem.”



   Reports can be created based on information in the database. The only report that
    will allow the user to print out information about a product that was sold at the resale
    store is “Solditem.”



   The resale store will use a menu to choose ways to manipulate the database. A
    user can add information, search, or print out reports.




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*The relationships between the five tables are shown in Figure 4




                    Product                           SoldItem
                    ProdID
                                                       ProdID
                   ProdType
                                                     InvoiceNum
                   DonorID
                   ProdDesc
                   ProdPrice
                   ProdCond

                                                           Invoice

                                    ProductType          InvoiceNum
                    Donor                                    Date
                                     ProdType              TotalSale
                  DonorID
                  FirstName          TypeDesc
                  LastName
                    Line1
                    Line2
                     City
                     State
                   ZipCode
                    Phone



         *** The fields in bold are the primary keys of the corresponding tables

                    Figure 4 – Relationship between the POS tables


Bar Code and Labeling System
      Visual Basic 6.0 (VB) was chosen to interface the point of sales database with
the Bar Code and Labeling System because of its powerful interfacing tools for
Microsoft Access. The scanner will be connected to the keyboard, and it will use the
keyboard to input information into a menu of searches and forms created using Visual
Basic. The keyboard will provide an input of bar code information read by the scanner
directly into a field located in the VB menu. The VB menu interface will then search
through the point of sales database and locate the desired data and display it for the
user. The VB interface will also accept input from the user and place it in the database.


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This will be accomplished by the VB interface using specialized functions that are being
written. Users will login to the Access interfacing software in order to use the database.
The user’s information will be stored in a separate database also created with Microsoft
Access.
        The bar code scanner SCLR17 and the Bar Code Active X Control labeling
software were purchased from Bars and Stripes for use in the Bar Code and Labeling
System. A hand held scanner was chosen because of its flexibility in supporting the
constant movement required by the resale store employees. This specific scanner was
chosen because of its ability to read bar codes from acceptable distances (11.8”), its
compatibility with many bar code symbologies, its large scanning width, and its
convenient keyboard interface. The labeling software was chosen because it can use a
standard Windows driver printer, is compatible with VB 6.0, and is easy to use.
Straight- forward use, considering the resale store’s employees lack of experience with
extensive computer technologies, is an important requirement. The relevant
specifications for the scanner and labeling software are listed below:


   SCLR17
       Automatically discriminates between bar code symbologies
       Width of window: 62mm
       Scanning width: 150mm
       Resolution: Max. 0.127mm (5 mils)
       Light source: 660 nm red visible LED
       Scanning rate: 45 (scans/second)
       Interface: Keyboard wedge, RS-232-C, Wand emulation
       Working temperature: 0-50c
       Working humidity: 20-80% RH
   Bar Code Active X Control Labeling Software
       Compatible with MS Access 97 and 2000
       Works with Visual Basic 6.0
       Supports 11 symbologies
       Control bar code orientation, size and placement


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      Control bar code color
      Control bar code text font


       The user login software is the first of two pieces of the bar coding system. The
second is the product database interface. The login software accesses a database
separate from the products to obtain and modify user information. The purpose of the
login portion is to provide more security for the product information. Only resale store
employees will be given access to the database. With this login software there are two
different types of users, those with administrator privileges and those without.
Administrators will have the ability to add new database users, change a current user’s
information, display a current user’s information, and change his/her login and/or
password. The non-administrator user will only be able to change his/her login and/or
password. After the user verification is complete, the user will be allowed to continue to
the database interface software. Here only the administrator will be allowed to delete
product records and modify invoices. All other functions will be granted to all resale
store employees.
   The Visual Basic Data Access Object tools were used to transport information to and
obtain information from the user database. The code to the login software is located on
the HFH ‘T’ and is in the VB project file named “login.vbp.” All forms used to guide the
user are in this VB project file also.




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