A "Primer" on how bar code and RFID work

1. Fundamentals of Automated Data Collection
Automated
Using Bar Code and RFID
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Introduction
1) Introduction
The first commercial use of the UPC bar code was at a grocery store in Ohio in 1973. The package scanned was a pack of
gum. Today we take the technology very much for granted but without bar codes
and bar code scanning technology, life would be very different. UPC Barcode
Imagine what FedEx and UPS would be without bar codes. Imagine how long it
would take to check out at the grocery if every item had to be keyed in by hand.
The list goes on - bar code technology in manufacturing, distribution, transportation
and healthcare reduces the amount of time needed to get products to stores and
hospitals.
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2. The three major benefits of bar code data collection include saving time
time,
reducing costs and increasing productivity Time savings accrue through
productivity
oductivity. Barcode & RFID
the elimination of hand written data. Hand written data is inherently
slow and error-prone. A bar code scan is accurate to within 1 error per 1
•Save time
million characters scanned. Cost reductions automatically flow from •Reduce
•Reduce cost
time savings. If a worker can process 10 orders per hour manually, •Increase productivity
productivity
another worker can process 50 orders or more via bar code scans. The
same is true for productivity gains - a worker who can produce more
results in less time is more productive.
The purpose of this book is to explain the fundamentals of bar code - how it works, how it is used, and how it integrates to
the world around us. In addition there will be an overview of RFID (Radio Frequency Identification) as it relates to
automated data collection.
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3. 2) Symbology
A bar code symbol is made up of alternating lines and spaces. Combining these bars and spaces in specific
ways is similar to using Morse code. Using Morse code to spell out SOS uses 3 dots (...) then 3 dashes (—
) and then three dots again (...). A bar code is a “machine readable
symbol” meaning that it can be decoded (turned back into number
and letters) by any of several types of scanner. The bars and spaces
are analogous to the dots and dashes.
Linear code
Using only bars and spaces, a bar code can represent numbers or
numbers and letters. In fact the entire ASCII character set can be
represented in bar code. When scanned by a laser scanner or imager
Stacked code
ASCII the bar code returns a signal pattern that is then interpreted by the
Characters bar code reader; turning the symbol back into numbers and letters.
Using bar code almost any item can be identified - part numbers, location IDs, packing
slips, shipping documents, driver licenses - the list is endless.
Matrix code
A “linear” bar code is one dimensional; that is, the information is the same whether
“linear”
you scan across the top, bottom or through the center. There are also 2 dimensional bar codes which
included “stacked” (many 1D codes stacked together) and “matrix” (a series of dots or lines).
“stacked”
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4. RFID (Radio Frequency Identification) also represents a ‘type’ of bar code which we will cover in more detail in a separate
section. The key to a bar code that is easy to scan is contained within the specifications for that symbology. Bar code
key symbology.
specifications are the rules on how the bar code is to be produced. Those rules include a few terms we must define.
“X
The “X” dimension - not science fiction but the width in “mils” (thousandths of an
inch) of the narrowest bar. So you will hear of a bar code referred to as 20 mil or 40
mil code; again that measurement is the width of any of the narrow bars in the printed
symbol. The X dimension is important for two reasons - 1) the wider the X dimension
the larger the overall symbol will be when printed. A bar code containing 12
characters will be smaller if the X dimension is 10 mil than if it is 60 mil and 2) the
larger the X dimension the farther away the bar code can be scanned.
Ratio
atio”
The “N Ratio” - the N ratio compares the width of the narrow bar (X dimension) with the width of the wide bar. The
ratio will usually be 2 times, 2.5 times or 3 times the X dimension or, said another way, a 10 mil narrow bar will have a 20
mil, 25 mil or 30 mil wide bar. Again this is important for the same two reasons, 1) the larger the N ratio the larger the
printed symbol will be and 2) the larger the N ratio the easier the bar code will be to scan from a distance as the wider bar
provides a stronger signal when scanned.
The Quiet Zones - are the blank white areas on either end of a bar code symbol. These are important
because if the symbol is printed to close to the edge of a label the bar code scanner may not be able to
pick up where that symbol begins or ends. Typically a quiet zone is defined as being 10X or 10 times
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the X dimension.

5. A device called a bar code verifier is basically a scanner with a
small integrated computer; when you scan bar code symbols
with a verifier it compares what it sees with the built in
specifications for that symbol and returns a letter grade. A, B
and C are acceptable, D or F are not.
Code 39 is used in many manufacturing operations including
the automotive industry; Code 128 encodes information
differently and allows more information to be compressed in
the same space as a larger Code 39 bar code. UPC is used in
retail; I2of5 is called Case Code and is often printed on corrugated
boxes. There are many other symbologies as well.
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6. Printers
3) Printers
The good news is that any type of printer can be made to print bar code symbols.
The bad news is that any type of printer can be made to print bar code symbols. This
is not gibberish; each type of printer has strengths and weaknesses when it comes to
printing bar codes.
Desktop laser and inkjet printers can be used to print shipping labels - both Fedex and
UPS offer online label printing that includes the shipping bar code. PC software is
available to format and print bar coded labels and even to integrate label printing into
other corporate software. Desktop printers are often used to print shipping tickets or
pick tickets and can incorporate bar code symbols into these documents.
The downside of desktop printers is that they are usually not rugged enough to print
high volumes of labels. Additionally the labels you can run through a desktop printer
are not very durable; they don’t have the strength of adhesive to stick to corrugated
boxes and the print can be damaged fairly easily.
Dedicated bar code printers are thermal in nature; that is, they use a print head that becomes hot.
There are two variations - thermal direct uses a hot print head to ‘burn’ the image into a coated paper
stock. Heating this coating turns it black thereby producing an image. Thermal transfer uses a similar
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7. hot print head but also uses a ribbon. The ribbon is melted onto
plain paper labels to produce an image. The labels and ribbons
are referred to as label ‘media’ and are a consumable that must be
replaced from time to time.
Thermal direct is cheaper because there is no ribbon but the label
material is still sensitive to heat and can yellow with time.
Thermal direct is best for labels that will be used within a six
month window of printing. Thermal transfer is more expensive
due to the ribbon but the labels will not change over time and are
not sensitive to heat.
Dedicated thermal bar code printers are also highly durable and
designed to be used under dirty and rough conditions. There are
also portable versions of these types of printers used for receipt
and ticket printing at venues such as outdoor events.
The shortcoming of this type of printer is the greater expense of consumable supplies and the limited print widths
available. Print width on bar code printers is usually 4 inches or 6 inches and the length of the label is
limited only by the length of the roll of bar code media.
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8. Bar code printers can be set up to print in “batch” mode or “on-demand” mode. Batch mode is used to produce a run of
labels ahead of time that will be used to label products. The information encoded on the label typically comes from the PC
itself or possibly from a data source such as a WMS or ERP program. These labels can have multiple bar code symbols that
may include part number, lot number, serial number, and/or a date code.
On-demand printing is utilized to print a bar code label at a specific time and containing specific information. An example
of this is a printer programmed to print a packing label when a manufactured unit comes to the end of the production line.
Bar Code Media is simply another term for the labels, ribbons and tags used in a bar code printer. As an example, Avery
makes a popular address label, the 5160, used to
create mailing labels for letters. If you printed bar
code on these labels they would most likely scan
well. However if you tried to label a batch of boxes
they would eventually peel off as the adhesive is not
that strong.
Labels made for bar code printers typically come in
rolls or in long ‘fan folds’. The most common size is
a 4" by 6" shipping label. The
adhesive on dedicated bar code
media is much more ‘aggressive’
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9. meaning it will stick on many materials and not come off easily.
There are also specialized label adhesives for use in food
preparation and freezing (frozen food plants), adhesive that can be
removed easily (post-it note adhesive) and others.
Ribbons used in Thermal Transfer bar code printers are usually
made of a plastic film coated with carbon. Passing between the
thermal print head and the label stock, the image is ‘melted’ onto
the paper and is very difficult to scratch or remove. The ribbon in
a thermal transfer printer is a ‘one shot’ roll and cannot be reused.
Print heads gradually wear out due to the fact that the moving
labels and ribbons are in direct contact with the print head.
Purchasers of bar code printers should investigate the print head
warranty from the manufacturer to see if they allow the use of
‘foreign’ media without affecting the warranty coverage.
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10. Readers
4) Scanners & Readers
The terms “scanner” and “reader” are often interchanged;
basically anything that can decode a bar code and change
it back into numbers and letters is a “scanner”. Anything
that can accept that decoded information is a “reader” .
For example, the omni-directional laser at your grocery
checkout is a scanner; the cash register is a reader.
For most of us, that particular scanner at the check out is
the one we’re most familiar with. It uses a low power
diode laser to produce a dot of red light. That red dot is
reflected against a spinning, faceted mirror to produce a
pattern of lines. When those lines cross the UPC bar
code symbol on a package of coffee a signal is reflected back to a photo eye inside the scanner itself.
That signal is decoded back into numbers and letters and sent up to the cash register. An important point here is that the
scanning replaces a human being having to type or key those numbers into the cash register - this is the fundamental benefit
of bar code; replacing slow human typing or hand writing with fast electronic scanning. That
replacement speeds up check out (or picking orders in a warehouse) and reduces the chance of error (a
human will make a mistake keying once in every 300 characters typed).
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11. Scanners typically use either a laser or an imager to “look” at the bar code. A hand held laser scanner (again something
most of us have seen at a local retail checkout; even brides-to-be are given a hand held terminal to scan items into their
bridal registry) uses a laser diode to produce a dot of light and a mirror flips the dot back and forth so fast that it appears to
the human eye as a solid line. These laser scanners flip the dot back and forth across the bar code symbol several hundred
times a second. There are specialized “fixed scanners” usually attached permanently to moving conveyor systems that can
scan up to 10,000 times per second and are used to capture bar code reads on items in motion on the conveyor.
An “imager” is related to digital camera. A solid state CCD (charge
coupled device) takes a picture of the bar code symbol; software inside
the device decodes it back into numbers and letters.
A bar code reader can take many forms. The cash register mentioned
before is a form of reader. An automated time clock at a factory or
business is a reader. A PC with a scanner attached is a reader. A hand
held “gun” like the ones used to check inventory at the grocery is a
combined reader AND scanner (which is what often causes the
confusion in terms). Solid State Imager
In manufacturing there may be a fixed terminal (reader) attached to a fork lift which directs the driver
to pick items or put away items and scan the item and location as they work. The scanner is typically
a “gun” form factor attached to the reader by a stretch cord. The scanner in this instance may be a
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12. long range scanner capable of scanning bar codes from a great distance from the bar
code label.
Hand held terminals today have the built in power of a regular PC usually running
Windows Mobile software; able to run very sophisticated programs. Additionally
there are programs running on mobile phones that
turn the built in digital camera into a bar code
reader.
Whatever its form, a bar code reader is designed
Handheld reader with scanner
to run software that automatically collects data as
the worker moves through their tasks. The
program is related to what the company does and
what the particular worker is doing. For example, a worker checking in parts
shipments will be updating the companies inventory by scanning the items as they are
checked in.
Forklift mounted reader
Prior to using a scanning system, someone would have to print a bill of lading and go
over every package by hand, make a manual entry of some kind, and then later key their manual
entries into a computer terminal or PC. The actual inventory of what was on hand would be
inaccurate for the length of time it took to hand count and key in the information. Annual physical
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13. inventory involved people with clipboards, markers and
sticky labels going through the entire physical plant hand
writing as they went.
A worker on the production line might scan bar codes to
indicate how many assemblies they had created or how
many items they had picked. Some companies will install
scanners attached to their time & attendance systems and
have workers scan in and out of the job.
A fully automated operation will use bar code to receive,
manufacture, put away, pick, ship, and inventory.
Hand held and vehicle mounted readers typically communicate wirelessly via a wi-fi network much like a wi-fi hot spot at a
restaurant or store. This allows the readers to update the company software in real time giving a much more accurate
picture of what is happening within their processes.
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14. WLAN
5) Wireless Networking and WLAN used in Data Collection
Once a mysterious area familiar only to the military and ham radio operators, wireless communication is commonplace
today. Not that we necessarily understand it any better but manufacturers of laptops and cell phones have worked hard to
make wireless networking much easier to use.
The wireless ‘hot spot’ your laptop connects to at Starbucks is simply
a way to eliminate the cable plugged into a port on the computer.
Wi-Fi, as it’s sometimes called, stands for “wireless fidelity”; a
throwback to when stereo music was called High Fidelity.
As it relates to bar code data collection, manufacturers and
distribution operations deploy such wireless networks in their
facilities thereby extending the computer network through large
buildings or even groups of buildings.
The hand held and vehicle mounted terminals used to track
inventory or shipping have basically the same radio setup as your
laptop computer which allows information on what is happening in the facility to be updated in real
time. Prior to the wide spread of Wi-Fi, wireless networking was limited to very complicated
installations requiring large amounts of specialized equipment.
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15. Today’s wireless installations carry voice and data and
allow for very sophisticated communications to take
place. In addition to data collection and walkie-
talkie (push to talk) networking, systems may even be
able to communicate with RFID tags to provide real
time location (RTLS) of people, parts or processes.
Care must be taken when installing Wi-Fi in a
manufacturing or distribution facility. Since radio
waves are reflected from certain surfaces and
absorbed by others, an professional experienced at
how radio works in these varying environments is
needed to guarantee radio coverage. In addition,
wireless networking has the potential to open your
network to hackers and phishers looking to steal
information. Additional care must be taken to add
safeguards to the wireless network to prevent these Access Points providing Wi-Fi Coverage
‘invasions’.
A WLAN or Wide Area Local Access Network uses cell phone technology to gather and send data. This
WLAN
technology is used most often in Mobility applications such as store delivery.
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16. 6) RFID basics
An RFID tag is analogous to a bar code label in that they both contain
encoded information. But a bar code always contains the same
information whenever it is scanned. An RFID (Radio Frequency
Identification) tag is a tiny integrated circuit with a tiny antenna
attached that usually encodes a unique number or bit of information
(called ‘static information’) or it may be able to change the information
contained in the chip (read/write tag).
The concept of RFID is that, in place of a bar Assorted RFID Tags
code scanner (laser or imager), an
interrogator (a type of radio that serves as the scanner and reader) fires a radio signal in the
direction of the tag via an antenna. Depending on the type of tag the radio signal strikes the
RFID tag and causes it to “respond” to the by sending back its information which is captured by
the interrogator.
Passive Tags have no internal power but use the energy of the interrogator radio to flash back a
response basically by reflecting the power of the interrogator. An Active
Tag contains a battery that allows the signal to transmit further increasing
RFID Reader
the distance that the tag can be read.
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17. A passive tag may only read from a distance of a few inches to a
foot. An active tag may be able to transmit its information for
several yards. An active tag is also more likely to be programmable,
meaning that the information contained in the tag can be changed
perhaps to reflect it’s location or something that has changed such as
a step in a manufacturing process.
Problems with RFID tags can make them difficult to implement.
Because radio waves reflect much as light waves do, the signal from
an interrogator may reflect in the wrong direction causing the tag to
be missed. RFID-tagged items made from metal may also block the
tag from being read. In fact there are many materials - water
Active RFID Tags content, heavy paper, etc - that can affect the readability of an RFID
tag.
Applications of RFID technology are best suited to places where there is no one attending to the scanning such as tracking
packages traveling down a conveyor line. Some companies have placed RFID tags on finished goods and placed
interrogators on either side of a dock door so that the tag is read as it is placed on the truck thereby verifying the load.
RFID installations are still somewhat of an art and require experienced integrators who understand the
process of placing interrogators and antennas as well as understanding how to choose the proper RFID
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tag technology.

18. Typically Technology
7) Applications Typically using Bar Code or RFID Technology
Receiving - the process of receiving raw materials in a manufacturing
facility or receiving finished goods at a distribution center or store.
This can be a challenging application for bar code. There are three
“if” conditions that must be met before this can work. IF your
suppliers bar code the items they ship to you and IF that bar code has
information your system can use (as opposed to it being THEIR
shipping label) and IF there is a way to compare those items against
orders then it may be possible to receive automatically using bar
code.
If items are not bar coded when they come off the truck, it may be
feasible to label them before putting them into raw goods inventory -
though this adds an additional step in the work process. It can also
be a problem if your facility uses the same dock doors for receiving
and shipping; can your programs differentiate between shipping and
receiving?
Receiving applications typically include a wireless network, hand held terminals, bar code printers, and
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an integrated software application.

19. Manufacturing - the process of combining raw materials
and/or components into a finished product (sometimes
referred to as ‘finished goods’) and WIP (Work in
Process) - the process of tracking an item through
manufacturing for the purpose of scheduling or tracking
the amount of time used in each step.
Knowing the exact location of an item as it is
manufactured can be a powerful Customer Service tool.
By bar coding the steps in the manufacturing process and
scanning the items as they are built, a real time picture of
the overall operation is possible. Customers looking for
updates can be given realistic time-frames for when their
order will be ready for shipment.
Manufacturing applications typically include a wireless
network, bar code labeling of work orders, fixed or
portable readers, and, for some applications, RFID tags
and readers.
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20. Time & Attendance - the process of tracking the work time of employees.
Most facilities use an employee identification some type. Time & Attendance systems usually use a fixed reader with a bar
code scanner, RFID reader, or Mag Stripe (like on your credit card) reader.
Inventory - the process of putting finished goods into storage locations
for use in filling orders. There are three types of inventory - raw goods
or component inventory, work-in-process inventory, and finished goods
inventory.
Knowing what you have to work with is a key to success in
manufacturing and distribution. A bar code inventory system links an
item number with a location by scanning both the item and the
location. Locations may vary widely; from shelf labeling in a retail
store to large reflective bar code labels used to identify racking in a
warehouse. Using bar coded inventory allows a company to have a
better idea of what they have on hand; replacing or reducing the
practice of annual inventories and cycle counting.
Inventory applications typically use a wireless network, bar code printers or pre-printed labels,
specialized location labels for identifying specific warehouse locations, and hand held or vehicle
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mounted terminals.

21. Picking/Shipping - the process of filling an
order from inventory and sending it to its
final location.
Orders entered by sales and administration
cannot be completed until they are picked
and shipped. Shipping an order usually is
the trigger for an invoice to be generated
for that order so it is important that it is
done accurately. Inaccurate shipments can
be costly for an operation; a mis-shipment
can cause delays in payment and
additional cost for correcting the mistake.
By scanning bar codes as a shipment is
picked, inventory can be kept accurate and
orders can be verified.
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22. Delivery/Mobile Applications - a class of applications directing
and tracking mobile workers as they perform daily tasks.
The list of mobile applications is long - route sales, route
accounting, proof-of-delivery, signature capture, service
dispatching, service accounting and service billing, GPS
tracking, turn-by-turn instructions and many others.
Mobile applications typically use a WLAN or wide-area local
area network; which in simpler terms means using cell phones
for communication. Portable terminals used in mobile
applications now combine bar code scanning, digital camera,
GPS tracking, signature capture and Windows Mobile software
into a single unit. There may also be battery-operated,
portable label or ticket printers for printing receipts, bills,
tickets, or other documents.
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23. 8) Conclusion
The application of bar code and RFID technology has dramatically changed the way business is done. Gone are the days of
hand tagging groceries and re-tagging them when the price changes.
While bar code usage is wide spread, there are still thousands of application possibilities. Wherever someone is hand
writing information or hand keying that information into a computer, there is room for automation. Automated Data
Collection using bar code and/or RFID can reduce the cost of information, speed the movement of information, and
increase the accuracy of information gathered - all resulting in increased productivity and reduced cost.
The key to this improvement can be found in a well designed system. ADC Integrated Systems has over 150 man years
experience with all aspects of AIDC and RFID. We can help you with system specifications, wireless networking, equipment
selection, installation, training and support. We offer a no-obligation review of your particular application.
Contact us via our website - www.adcisi.com -
or via email at sales@adcisi.com
or call 901-327-9946.
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24. Copyright 2009, ADC Integrated Systems, Inc.
2701 Union Avenue Extended, Suite 504
Memphis, Tennessee 38112
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