Portable Data Collection Solutions.
Finding One That's Right for You.

by Dirk Dusharme (columnist for Quality Digest Magazine)

All best-of-industry quality processes depend upon data collection. For manufacturing processes, the data often come from measurement instruments used to collect spatial, environmental, electrical, mechanical or physical characteristics from the part being manufactured. Twenty-five years ago, most measurement data were collected manually. But as computers became smaller, more affordable and faster, this function was turned over to them, decreasing the time and increasing the accuracy of data collection.

Years ago, setting up an automated shop floor data collection system involved straightforward decision making: You either bought a dedicated data collection system, had one custom-designed for you, or you put one together yourself using a PC, a data collection box, a multiplexor and some sort of data collection software to communicate with the whole mess.

But these dedicated systems were large, usually sitting either on a benchtop next to where measurements needed to be taken, or on roll-around carts for limited portability. Unless you were built like Arnold Schwarzenegger, you probably didn't lug these systems onto an aircraft wing to take measurements. For data collection from a remote location, you did it the old-fashioned way: a caliper in one hand, a clipboard in the other and a pencil clenched between your teeth. It was tiring, time-consuming and error-prone. Worse yet, the handwritten data had to be transcribed back into a computer for analysis, requiring more time and providing more opportunities for error.

Fortunately, those days are long gone. Portable data collection units are now available in a range of different sizes. Each will upload a measurement process (often called a "route") from a host computer and, once on the shop floor, guide the operator through the measurement protocol using onscreen prompts, greatly reducing training time. They all have an LCD screen to display measurement instructions and results, including alarms for out-of-control processes and ports that will connect to almost any measurement device. All allow alphanumeric entry either through a QWERTY keyboard or a small alphanumeric keypad. All provide varying degrees of on-the-spot SPC data analysis and will download data to a PC workstation for further data analysis. The main differences between products is the number and types of devices they can connect to, the size of the screen and keyboard, the amount of on-the-spot data analysis, battery life, ease of use and special functions.

Is a portable for you?

Although all that functionality in a small package might sound too good to pass up, a portable data collector isn't for everybody. "You go to a portable data collector because you have to," says Erich Shroeder, product manager for DataMyte, an industry leader in portable data collection systems. "If your parts are spread out or too big, you go to a portable."

It also depends upon the job function of the person doing the work, adds Frank Skog, DataMyte's application manager. "For the person whose only job is to collect data, a portable makes sense," he explains. "For a person who takes data while working at a milling machine for instance, a dedicated system may make more sense."

As supplier audits become more the norm and, in some cases, mandated, the ability to quickly set up and take measurements at a supplier's location may also dictate the use of a portable. Most portable data collectors give instant reporting, letting auditors make crucial decisions within minutes instead of hours or days.

A portable probably isn't for you if you need to monitor a large number of devices. "Someone once called me up asking to collect 32 channels of analog data," recalls Oliver King-Smith, president of Tescina Inc., the leader in Palm OS-based data collection. "It quickly became apparent that by the time I was done, he would have a small suitcase filled with connectors that he would then plug into his hand-held. If the amount of wires and connectors is vastly greater than the size of the hand-held, you need to start asking yourself if using a PC might not make more sense."

Finally, if you don't need the functionality of a desktop system, a portable may be more cost effective--even when used as a dedicated data collector.

What to consider

So what things should you think about before deciding on a portable data collector?

Location. Depending on where you need to take measurements, size and weight are considerations. Will the unit and any adapters physically fit where they need to go? Will the operator have to carry the collector continuously or can it be set down? A four-pound unit slung over your shoulder will feel like 40 pounds after eight hours.

One-, two- or no-handed operation: Lacking a flat surface, will the operator need to hold the unit in one hand and measure or input data with the other, or will the operator need both hands free? This ties into the size and ergonomics of the unit as well as its user interface. Some come with a footswitch for triggering actions on the unit, leaving both hands free.

Battery life. All portables run on battery power; some can also run on line power. If the unit you are considering uses only battery (or line power isn't available at the site), will the battery last long enough for your application?

Text entry. Does your application require the operator to input a lot of free-form text? If so, a telephone-style keypad or pen stylus will be tedious. Consider a portable with a QWERTY keyboard.

Ruggedness. What kind of environment will the unit operate in? Is there a lot of dust, spray or other contaminants? Verify with the manufacturer that the unit is designed for use in such environments.

Display. Most portables have a small LCD display. You need to determine how the display will be used in your application and whether a small display will tire the operator. If you constantly need to refer to run charts or other data, a larger screen may be called for.

Desktop analysis. Although all the units shown here will export collected data for use in any third-party analysis software, each is designed to connect directly with one or more popular SPC software packages. If your company is tied into specific analysis software, consider a portable that works directly with your package.

Cabling. Some portables require special adapter cables for each type of gage to be used; others work directly with the cables supplied by the gage manufacturer. If you already have a lot of manufacturer-supplied cables, this may be a consideration.

Wireless. Do you want or require wireless communication with your portable? One advantage with a wireless system is data integrity; the data is sent to a host computer instead of being stored on the unit. If the unit is broken or lost, you still have the data. A wireless system also allows functions such as e-mail and access to documents stored on the host computer. How-ever, wireless units may not work well in areas with a lot of electrical noise (e.g., motors or welders), which can cause dropouts (think cell phone). Before buying a wireless system, make sure that it will work in your environment and that the unit has some sort of data integrity system that prevents lost data in the case of dropouts.

Ports. How many gages and gage types do you need to monitor at one time?

Memory. How much data will you collect before downloading the unit? This isn't as much of an issue with wireless units.