Bar Code and RFID Fundamentals

8/8/2019 Bar Code and RFID Fundamentals

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Fundamentals of Automated Data Collection Using Bar Code and RFID

An e-book from ADC Integrated Systems, Inc. Visit us at www.adcisi.com for additional

information on Automated Data Collection systems and services. Request a site visit, read our

blog, ask for a quotation - we have over 150 man years experience in solving business processproblems with bar code and RFID.

1) Introduction

The first commercial use of the UPC bar code was at a grocery store in Ohio in 1973. Thepackage 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.

Imagine what FedEx and UPS would be without bar codes. Imagine how long it would take tocheck 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.

The three major benefits of bar code data collection include saving time, reducing costs and

increasing productivity. Time savings accrue through the elimination of hand written data. Handwritten data is inherently slow and error-prone. A bar code scan is accurate to within 1 error per

1 million characters scanned. Cost reductions automatically flow from time savings. If a workercan process 10 orders per hour manually, 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 inless 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 bar code data collection.

2) Symbology

A bar code symbol is made up of alternating lines and spaces. Combining these bars and spacesin 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 readablesymbol" 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.

Using only bars and spaces, a bar code can represent numbers or numbers and letters. In factthe entire ASCII character set can be represented in bar code. When scanned by a laser scanner

or imager the bar code returns a signal pattern that is then interpreted by the bar code readerturning 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.

A "linear" bar code is one dimensional; that is, the information is the same whether you scanacross 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).

RFID (Radio Frequency Identification) also represents a 'type' of bar code which we will cover inmore detail in a separate section.

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The key to a bar code that is easy to scan is contained within the specifications for that

symbology. Bar code specifications are the rules on how the bar code is to be produced. Thoserules include a few terms we must define.

The "X" dimension - not science fiction but the width in "mils" (thousandths of an inch) of thenarrowest 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 bewhen printed. A bar code containing 12 characters will be smaller if the X dimension is 10 milthan if it is 60 mil and 2) the larger the X dimension the farther away the bar code can be

scanned.

The "N Ratio" - the N ratio compares the width of the narrow bar (X dimension) with the widthof 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 isimportant 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 widerbar 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 scannermay not be able to pick up where that symbol begins or ends. Typically a quiet zone is defined as

being 10X or 10 times the X dimension.

A device called a bar code verifier is basically a scanner with a small integrated computer; whenyou 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 printedon corrugated boxes. There are many other symbologies as well.

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; eachtype 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 andprint 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 intothese documents.

The downside of desktop printers is that they are usually not rugged enough to print high volumesof labels. Additionally the labels you can run through a desktop printer are not very durable; theydon'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 becomeshot. 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 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 notchange over time and are not sensitive to heat.

Dedicated thermal bar code printers are also highly durable and designed to be used under dirtyand rough conditions. There are also portable versions of these types of printers used for receiptand 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 andthe length of the label is limited only by the length of the roll of bar code media.

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 that will be used to label products. The information encoded onthe 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, lotnumber, 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 amanufactured 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 youtried 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 commonsize is a 4" by 6" shipping label. The adhesive on dedicated bar code media is much more

'aggressive' meaning it will stick on many materials and not come off easily. There are alsospecialized 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 think plastic film coatedwith 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 printeris 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 headwarranty from the manufacturer to see if they allow the use of 'foreign' media without affecting

the warranty coverage.

4) Scanners & Readers

The terms "scanner" and "reader" are often interchanged; basically anything that can decode abar 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 grocerycheckout 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 thosenumbers 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 amistake keying once in every 300 characters typed).

Scanners typically use either a laser or an imager to "look" at the bar code. A hand held laserscanner (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 adot 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 hundredtimes 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 codereads 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 andletters.

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 areader. 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).

In manufacturing there may be a fixed terminal (reader) attached to a fork lift which direct 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 thisinstance may be a 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 Mobilesoftware, 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 to run software that automatically collects dataas 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 beupdating the companies inventory by scanning the items as they are checked in.

Prior to using a scanning sysstem, 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 thelength of time it took to hand count and key in the information. Annual physical inventoryinvolved 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 hadcreated 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 theirprocesses.

5) Wireless networking and WLAN

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 butmanufacturers 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 cableplugged 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 suchwireless 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 basicallythe 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 waslimited to very complicated installations requiring a large amount of specialized skill and

equipment.

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 timelocation (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 athow 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 phisherslooking to steal information. Additional care must be taken to add safeguards to the wireless

network to prevent these 'invasions'.

6) RFID basics

An RFID tag is analogous to a bar code label in that they both contain encoded information. But abar 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 tochange the information contained in the chip (read/write tag).

The concept of RFID is that, in place of a bar code scanner (laser or imager), an interrogator (atype 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 itto "respond" to the by sending back it's 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 the distance that the tag can be read.

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 toreflect it's location or something that has changed such as a step in a manufacturing process.

Problems with RFID tags often make them difficult to use. Because radio waves reflect much aslight waves do, the signal from an interrogator may reflect in the wrong direction causing the tagto be missed. RFID-tagged items made from metal may also block the tag from being read. In

fact there are many materials - water 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 placedRFID 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 whounderstand the process of placing interrogators and antennas as well as understanding how to

choose the proper RFID tag technology.

7) Applications typically using bar code or RFID

Receiving - the process of receiving raw materials in a manufacturing facility or receiving finishedgoods at a distribution center or store.

This can be a challenging application for bar code. There are three "if" conditions that must bemet 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 receiveautomatically 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 an integrated software application.

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 Servicetool. 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 canbe 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.

Time & Attendance - the process of tracking the work time of employees.



Most facilities use an employee identification some type. Time & Attendance systems usually usea 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. Locations mayvary 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

mounted terminals.

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 andshipped. 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; amis-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 beverified.

Delivery/Mobile Applications - a class of applications directing and tracking mobile workers as theyperform 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-turninstructions 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 nowcombine 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 printersfor printing receipts, bills, tickets, or other documents.

8) Conclusion

The application of bar code and RFID technology has dramatically changed the way business isdone. 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 withsystem specifications, wireless networking, equipment selection, installation, training and support.

Contact us via our website - www.adcisi.com - or via email at [email protected] or call 901-327-9946.



Bar Code and RFID Fundamentals

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