Mobile Technology
Mobile Basics and General Information:
Mobile terminals or "Portable Data Terminals (PDTs)" are used to
bring the barcode reader to the barcode. For instance, in a grocery
store environment, the customer brings the barcode to the scanner.
However, when the time comes to do a monthly or quarterly inventory,
it just won't make a lot of sense to bring the products to the front
of the store. That's where PDTs come into play. There are a variety
of options, including scanners, numeric keypads, alphanumeric keypads,
character displays and graphical displays. The following information
should help you understand the functionality of PDTs. Selecting
the proper PDT can make the difference between efficiency and inefficiency.
T&W Enterprises can match the proper PDT to your business needs.
A Portable Data Collector is made up of the following components:
Scanner
Do you even need to read barcodes? For example, someone who reads
meters for the electric company has no need to read a barcode. He
just needs to key in some data.
Integrated
Some PDTs have a scanner built into them. This "integrated" scanner
might come in different models, such as standard range, long range
and high visibility (see Scanner Assist for more on scan engines).
If the PDT's integrated scanner will read 100% of your business'
barcodes 100% of the time, then it may make sense to go with an
integrated scanner. The scanners on some PDTs can twist to accommodate
right-handed or left-handed users.
Tethered
Remember playing tether ball as a kid? The ball was "tethered" to
the pole with a rope. Tethered PDTs are similar. For example, you
might fall in love with a PDT that you've selected but this particular
PDT only has a standard range integrated scanner and you need a
long range scanner. This is when you need to tether a long-range
scanner to the PDT. The scanner will then be able to read barcodes
from 20 feet, and the decoder built into the PDT will decode the
barcode. Of course, this would only work on those PDTs that have
an external scanner port.
Display
Character-based
Some businesses simply need to collect the item, quantity, and location
during a cyclical inventory. They would require character-based
PDTs.
Graphically-based
A graphically- (or pen-) based PDT is used with a Windows-like application.
For example, a cola delivery person at the grocery store could select
the store from a drop-down menu, select the item from a drop-down
menu, and then identify a quantity. All of this could be done with
a pen-based terminal. This type of terminal is also very useful
for police officers who are on site reconstructing an automobile
accident. Rather than drawing the facts on a piece of paper, they
could use a pen-based terminal.
Hybrid
There may be times when your business needs to display character-based
information, but also need to collect a signature. This is when
a "hybrid" PDT comes into play. You don't have to worry about having
to program a Windows-based terminal, but you still can capture a
signature.
Keypad
It is important that we match the terminal to your business needs.
If you are doing an inventory and only collect the item and quantity,
then you need a character-based PDT with a numeric-only keypad.
However, if you also are collecting location information, and the
locations include letters, then you need an alphanumeric keypad.
Don't stop there, though. Are the users wearing gloves? If so, the
size of the keys makes a difference. When selecting the best keypad
for your business application, you must take into consideration:
- Who is using the PDT
- What type of information you are collecting
Interface
Ask these questions: How will your business get the application
onto the PDT? How will I get the data off the PDT?
Serial
Some PDTs have an RS-232 port on the bottom of them. It may be a
DE-9 connector or a RJ connector. Either way, it uses serial communications
for getting data to and from the PDT.
Optical
You need to have some means of getting data to and from PDTs that
have no physical ports on the outside of them. These PDTs literally
use lights to exchange data. As you know, meter readers also work
on rainy days, so they need a PDT that is designed to continue operating
while exposed to dust and splashing water. That's when you'll need
a device with an "IP54 rating."
IrDA
IrDA (The Infrared Data Association) is another means of sharing
data between two IrDA-compliant devices. For example, a PDT and
a printer might have an IrDA port on them. This would allow the
user of the PDT to point the IrDA port on the PDT toward the IrDA
port on the printer to begin printing. No cabling is required. However,
one downside to IrDA is that it requires a clear line of sight.
Unless the two devices are looking directly at each other at a close
proximity, the "receiver" (printer) will not "see" the "transmitter"
(PDT).
Memory
ROM: On a PDT, this is where device settings (similar to BIOS on
a PC) are stored. This also is where the manufacturer stores information
necessary for starting up the terminal and storing an application
on it. This area is only accessible by the manufacturer.
Non-Volatile Memory (NVM) Also called "NVRAM," this is where the
application is usually stored. Power is not required for its existence,
so in that sense, it is not volatile.
RAM: Just like on a PC, this is where applications go to play.
The application is copied from NVM to RAM and it runs from there.
Operating system commands, drivers, and other frequently accessed
information are also stored in RAM. This simply maximizes the speed
of the application. When power is lost, so is all the information
stored in RAM.
SRAM: SRAM is typically used for the storage of "look-up" files
and sometimes for the storage of applications where there's not
enough NVM to store the application (or it's just the programmer's
preference to have it stored on an SRAM card). It's like a hard
drive, but it is "battery-backed." As long as the battery is good,
so is the data. If the battery dies, so does the data. (Back to
our example of the meter reader: Wouldn't it be nice if the PDT
would automatically display the address of the current customer
and his next customer and tell him where the meter is on the house?
All that information could be stored in a file that was downloaded
to the PDT. The application on the PDT would "look up" that information
and display if for him.)
Flash: "Flash is like a floppy." Remember that. Flash is functionally
the same as SRAM, but does not need a battery to maintain the data
stored on it, and is slower than SRAM.
Accessories
Communications Dock
A communications dock is recommended if your business is using a
PDT on a daily basis. It's not practical to expect the user to plug
a communications cable into the bottom of the unit every time he
wants to upload the data to the host. This is where the cradle comes
in. It's also a handy place to store the PDT and to charge the battery.
Further, a cradle is required for PDTs with an optical interface.
Batteries
Alkaline: Use it until it dies, then dispose of it in accordance
with local ordinances. We're talking your typical 9V and "AA" battery
here.
Nickel Cadmium (NiCd): NiCd batteries are the first generation
of rechargeable batteries. You can use it until it dies, recharge
it, and go back to work. The problem with NiCd batteries is what
is commonly referred to as the "memory effect." If a battery is
used for the same amount of time between recharges, it will soon
only allow the battery to be charged to that amount. For example,
if you use a battery for 4 hours everyday before recharging, that
battery will soon develop a memory and only allow 4 hours of use.
Proper battery maintenance is of supreme importance with NiCd batteries.
Do not re-charge them until they have been totally drained.
Nickel Metal Hydride (NiMH): NiMH batteries are the next generation
in the world of re-chargeable batteries. These batteries have no
"memory effect" and tend to have a longer life than NiCd batteries,
but are more expensive than NiCd.
Lithium Ion (LIo): LIo batteries are rechargeable, have no memory
effect, have a longer life than NiMH, and are more expensive than
NiMH batteries.
Battery charger: If you can charge the battery while the battery
is in the PDT, then why would you need a battery charger? Because
the PDT might need to be used on more than one shift a day. Also,
what if the battery dies? For this reason, we always recommend at
least two batteries per PDT. Some cradles can charge an additional
battery, so an additional charger may not be required. Otherwise,
there are single and multi-slot chargers.
Holster: A holster holds the PDT so that you can use both hands.
Of course, a holster would not be able to also hold a tethered scanner.
Printer: Some PDTs have the ability to be connected to a portable
printer. This would be very helpful for someone that needs to re-print
shelf labels at a store. Every portable thermal printer has a unique
programming language, so it won't be a "plug and play" solution.
Typically, printing is done either through the serial port or the
IrDA port.
Application Development
PDTs generally are not devices that you take out of the box and
go to work with. An application must be written to run on the PDT,
and you must also be able to make use of the collected data at the
host end.
Operating Systems
Be aware that different PDTs can have different operating systems.
Some have one version of DOS, while others have a different version
of DOS. Some might have Windows and some might have Windows CE.
Operating systems may vary from PDT to PDT.
Application Development Kit (ADK)
If you need to get to the fullest potential of the terminal, then
the ADK is for you. But you may have to spend a lot of time writing
your application.
Matching a PDT to an application: When matching a PDT to your business
application, T&W Enterprises will access the needs of your business.
There may be things that you are not aware of that would help make
your employees and business more productive. By understanding the
capabilities and limitations of using mobile terminals, T&W Enterprises
is able to determine whether your business actually needs a wireless
or mobile solution (see Wireless Assist).
For more information on Mobile Technology or if you don't have
the expertise to write an application, contact T&W
Enterprises Technical Support.
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