Data capture basics

Data capture technologies like bar code scanning, voice and RFID ensure that the right information is collected at the right time.

By Bob Trebilcock, Editor at Large -- Modern Materials Handling, 7/1/2007

The supply chain runs on information.

"Information is how I keep track of my inventory, what's going on in my operations, and how I get visibility into my supply chain," says Dick Sorenson, director of RFID for LXE (800-664-4593). "As the demands on my distribution center for efficiency and accuracy increase, I have to have the right data and I have to have timely data."

Mobile computing, bar code scanning, RFID and voice technology are the tools most often used to capture and share data with the supply chain systems that turn data into information to manage processes and inform decision making.

And while those technologies once worked independently, today's data capture systems are working together to enable new and more efficient processes. "We're seeing a convergence of multiple data capture technologies, like voice, RFID and bar code scanning in one device," says Sorenson.

MOBILE COMPUTING

Workstation computers may be ideal for sharing instructions with operators who remain in one place. But when it comes to materials handling, products and operators are on the move.

Mobile computers that communicate wirelessly with a host computer system over a facility's WiFi network enable associates to receive work instructions and capture information in real time wherever the work gets done. In addition to communication, workers can key data into a mobile computing device.

That's why mobile computing is the foundation of any automated data capture solution, regardless of whether the system scans a bar code, reads an RFID tag or uses voice technology.

There are two main types of mobile computing devices:

• Vehicle-mounted computers are designed to work with lift trucks and walkies. "A vehicle-mounted computer will usually have a bar code scanner tethered to it," says Sorenson. "Both will communicate wirelessly to the network, which is what gives you real-time capability."

• Ruggedized handheld devices are available in a variety of form factors, depending on the job. Order pickers carry an integrated handheld device that includes a scanning engine for bar codes or a reader for RFID tags. Supervisors who are not scanning as often as an order selector may carry mobile computers in a PDA form factor.

Whatever the form factor, today's mobile computers are nearly as powerful as a desktop.

"Today, you're able to run the applications you need on an Intel-based platform running an open system like Windows, Windows CE and Windows.Net in a device that fits into the palm of your hand," says Kevin Prouty, senior director of manufacturing solutions for Motorola (866-416-8545).

BAR CODE SCANNING

The first commercial bar code was scanned in a grocery store in Ohio three decades ago. Since then, bar codes have become the most ubiquitous method for collecting information in the supply chain.

In any solution using bar codes, there are two considerations:

1. Choosing the type of bar code or bar code label that is right for the application.

2. The type of scanning device.

Bar codes

At least three types of labels are found in industrial settings today.

1. 1D, or linear, barcodes are the familiar arrangement of black and white lines and spaces used to create the Universal Product Code (UPC). In a warehouse or manufacturing plant, a bar code may also be used for other purposes, like identifying a storage location in a rack system.

2. 2D bar codes come in a variety of forms, but common to all is that information is encoded both vertically and horizontally. "A 2D bar code is typically used when you need more information than can be contained in a UPC code," says Sorenson. "In the pharmaceutical industry, for instance, you might need a date and lot code in addition to a product code."

3. Direct part marking is a technique for applying a unique identifier directly to a part that can be used in the future for tracking and tracing.

After choosing the type of bar code, the next decision involves the type of scanner for reading the bar code.

Scanners

Laser scanners, which read 1D bar codes, are the most common. These devices read bar codes in conjunction with an oscillating mirror that automatically moves the beam back and forth across the bar code, according to Tracy Hillstrom, group manager for Intermec (425-348-2600).

Imaging technology can also read 2D bar codes and direct part markings and is beginning to take a larger share of the market. Image systems capture an image of the bar code, much like a digital camera. Software is then used to decode the image.

"Imaging technology is more tolerant of the conditions our customers face in an industrial setting," says Hillstrom. "With an auto-focus feature, they can capture images, and in the future capture video, from a few inches away up to 30 or 40 feet away."

Regardless of scanning technology, bar code scanners are available in hand-held devices and fixed devices, which are used to automatically scan packages without human intervention.

"Fixed scanners are most commonly used as part of a conveyor solution," says Brian Rostad, product manager of identification systems for Sick (800-325-7425). "You're reading cartons as they're unloaded onto a conveyor, before they go into an automated storage and retrieval system, or prior to a sortation system."

Because fixed solutions work without an operator, they tend to have higher performance requirements. "A hand-held scanning device might cost $100," says Adnan Ahmed, vice president of marketing for Accu-Sort Systems (800-227-2633). "An automated solution that can read cartons traveling at 600 feet per minute on a conveyor may run up to $20,000."

RFID

As anyone who has followed the news aboutWal-Mart knows, RFID (radio frequency identification) uses radio technology to electronically encode tags that can broadcast unique information about a product or asset. In the right application, RFID offers several advantages over bar codes.

• No human intervention is required to read an RFID tag, which broadcasts the information on the tag to an RFID reader.

• RFID can work in hostile or hazardous environments where bar codes won't work, like a paint line in an automotive factory: Paint over the tag and it will still broadcast its signal.

• RFID tags can carry considerably more information than a bar code.

As with bar codes, RFID readers are available in a variety of form factors, says Joe Melo, product manager for RFID and handhelds for Psion Teklogix (905-813-9900). Fixed readers can be installed at portals, like a dock door, or integrated as part of a conveyor line. Handheld devices can be worn or carried by an operator, and vehicle-mounted readers can be mounted on a lift truck.

"The more important consideration is what operating frequency to use, which will vary according to the application," says Melo.

Passive vs. active tags

Three frequencies, or tag types, are commonly used in industrial applications today:

1. High frequency (HF) tags have been used to identify and track assets for decades. These tags have a limited read range of 2 to 6 inches from the reader.

2. Ultra high frequency (UHF) tags have become popular over the last four or five years as a result of the mandates for tracking cartons and pallets. UHF tags can carry more data than an HF tag, and they have longer read ranges of up to 8 feet. HF and UHF tags are known as passive tags. They have no power source. Instead, they are powered when interrogated by a radio signal from an RFID reader.

3. Active tags, on the other hand, are equipped with a battery for power. They broadcast a signal that can be read by any reader within range. Some active tags have read ranges of hundreds of feet, making them ideal for asset tracking solutions like locating a trailer in a yard.

Active tags are also considerably more expensive than passive tags. For that reason, they are used to track very high value assets or in closed loop applications where the same tag might be used hundreds of times.

VOICE TECHNOLOGY

Like most bar code solutions, voice technology works with an operator. Like RFID, voice is a hands-free, eyes-free technology.

"Voice takes a very human approach to communication with a computer system," says Tom Kerr, director of applied research for Vocollect (412-349-2515). "The solution turns computer commands into vocal commands and creates a two-way dialogue to talk operators through their tasks."

A voice system consists of a mobile computer that communicates wirelessly with a management system of records, like a warehouse management system, manufacturing execution system or an ERP system. The operator also wears a headset with a microphone to communicate back with the mobile computer.

One advantage in the multicultural environment of many warehouses today is that a voice system can be programmed to communicate in the operator's native language and dialect. "We have one DC in Boston working with six different languages," says Rich Hayden, director of business development for Voxware (609-514-4100).

Voice is most often applied in labor-intensive activities in the warehouse, like piece picking, putaway, replenishment and cycle counting. "Any application that requires a number of touches is ideal for voice because the operator's hands and eyes are free," says Hayden. "Since operators don't have to stop to scan a bar code, they can improve productivity and accuracy."

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