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V550-A20 Operation Manual
Glossary
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Moving-Beam Bar Code Scanner
- A device that dynamically
searches for a bar code symbol by sweeping a moving optical
beam through a field of view called the scanning zone. Automatic
bar code reader that reads codes by sweeping a moving optical
beam through a field of view. Moving-beam scanners are usually
mounted in a fixed position and read codes as they pass by.
Multidrop Line
- A single communications circuit that intercon-
nects many stations, each of which contains terminal devices.
See EIA-485.
NAK (Negative Acknowledgment)
- A control character used to
indicate that the previous transmission block was in error and the
receiver is ready to accept retransmissions.
Narrow Bar (NB)/Narrow Space (NS)
- Smallest code element,
bar or space, in the bar code symbol. Also known as the X
dimension.
NCDRH
- (National Center for Devices and Radiological Health)
This organization (a service of the Food and Drug Administration)
is responsible for the safety regulations governing acceptable
limitations on electronic radiation from laser devices. Omron is in
compliance with the NCDRH regulations.
Near Distance
- The distance (in inches) from the face of the
scanner to the
closest
point at which a code can be successfully
scanned.
NEMA (National Electrical Manufacturers Association)
- In
order to rate the quality of an enclosure, NEMA has developed a
system for rating all enclosures. A partial list of NEMA enclosure
types is shown below:
NEMA Ratings
3
Enclosures are intended for indoor or outdoor use
primarily to provide protection against windblown dust, rain, and
sleet, and is undamaged by the formation of ice on the enclosure.
4
Enclosures are intended for indoor or outdoor use
primarily to provide protection against windblown dust and rain,
splashing water, and hose-directed water; undamaged by the
formation of ice on the enclosure.
4X
Enclosures are intended for indoor or outdoor use
primarily to provide protection against corrosion windblown dust
and rain, splashing water, and hose directed water; undamaged
by the formation of ice on the enclosure.
6
Enclosures are intended for use indoors or outdoors
where occasional submersion is encountered.
12
Enclosures are intended for indoor use primarily to
provide a degree of protection against dust, falling dirt, and
dripping noncorrosive liquids.
13
Enclosures are intended for indoor use primarily to
provide a degree of protection against dust, spraying of water, oil,
noncorrosive coolant.
NVC
(Non-Valid Code) - Defines the condition that occurs when
an object has been scanned and no bar code could be decoded.
Usually, this indicates that either no code was on the object or the
code was badly damaged and could not be decoded.
No-Read -
When the scanner is unable to decode a bar code as it
passes through the scan zone.
Non-Read
- The absence of data at the scanner output after an
attempted scan due to no code, defective code, scanner failure or
operator error.
Odd Parity
- A data verification method in which each character
must have an odd number of on bits.
Omnidirectional
- Orientation is unpredictable and can be ladder,
picket fence, or any angle in between. A single scan line is not
sufficient to scan bar codes oriented omnidirectionally.
Operating Range
- The sum of the scanner’s optical throw and
depth-of-field.
Optical Throw
- Measured distance from the scanner’s window to
the near reading distance of the depth of field. Typically, this is
the closest a bar code can be to the scanner’s window and still be
properly decoded.
Optimum Reading Distance
- Typically, the center of the depth
of field.
OCR
- Optical Character Recognition.
Orientation -
The alignment of the code’s bars and spaces to the
scan head. Often referred to as vertical (picket fence) and
horizontal (ladder).
Oversquare
- Used to describe bar codes that are taller (from top
to bottom of the bars) than they are wide (from first to last bar).
Package Detection
Trigger
- The standard abbreviation for a signal indicating that an
object is passing by the scanner is called Trigger. This signal
indicates to the scanner to start or stop reading.
Trigger Cycle
- The time during which the scanner is attempting
to read the bar code.
Hardware Trigger
- This is an electrical signal from a relay,
photoelectric or proximity sensor, or limit switch indicating that an
object is passing by the scanner.
Start and End of Trigger -
The trigger cycle begins when the
photoelectric sensor is blocked and continues until the photoelec-
tric sensor is unblocked. Relay decisions and data communication
take place after the end of the trigger signal.
Serially Controlled Trigger
- A serial message from an external
device that controls the trigger cycle.
Continuous Read -
This form of trigger requires no input signal.
The scanner is continuously attempting to decode bar codes.
When a scanner is in Continuous Read, there is no way of
determining if there is a package present or a NO-READ.
Package Spacing
- This is the spacing between items on a
conveyor. Package spacing is measured one of two ways:
Leading edge of one box to leading edge of the next or trailing
edge of one box to trailing edge of the next. Package spacing is
critical to system operations.
Parameter
- A value or opinion that you specify to a program. A
parameter is sometimes called a
switch
or an
argument
.
Parity Bit
- A bit that is set at “0” or “1” in a character to ensure
that the total number of 1 bits in the data field is even or odd.
Pen Scanner
- A pen-like device either connected by wire to a
device, or self-contained, used to read bar codes. Requires direct
contact with the symbol.
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