Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Barcode RFID Fundamentals


Published on

A "Primer" on how bar code and RFID work

Published in: Technology, Business
  • Login to see the comments

Barcode RFID Fundamentals

  1. 1. Fundamentals of Automated Data Collection Automated Using Bar Code and RFID An e-book from ADC Integrated Systems, Inc. Visit us at 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 process problems with bar code and RFID. 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.
  2. 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.
  3. 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”
  4. 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 the X dimension.
  5. 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.
  6. 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
  7. 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.
  8. 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’
  9. 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.
  10. 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).
  11. 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
  12. 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
  13. 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.
  14. 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.
  15. 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.
  16. 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.
  17. 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 tag technology.
  18. 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 an integrated software application.
  19. 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.
  20. 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 mounted terminals.
  21. 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.
  22. 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.
  23. 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 - - or via email at or call 901-327-9946.
  24. 24. Copyright 2009, ADC Integrated Systems, Inc. 2701 Union Avenue Extended, Suite 504 Memphis, Tennessee 38112 901-327-9946