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Quadrus EZ Reader User’s Manual
Glossary of Terms
Connector—Physical device (plug or socket) on a device or cable to provide in/out con-
nectivity for various circuits and pins.
Concentrator—Intermediary device that relays data from readers to a host and com-
mands from the host to the reader or other devices.
Counter—Memory space provided to keep track of reader events.
Daisy Chain—Linkage of master and secondary readers to allow data to be relayed up to
the host via auxiliary port connections.
Decode—A good read. The successful scanning and decoding of the information
encoded in a bar code symbol.
Default—Restores ROM or Flash settings, initializes serial commands and resets all
counters.
Delimited—A command or field that is bracketed by pre-defined characters.
Decode Rate—The number of good reads per second decoded by the reader.
Darkfield Illumination—Lighting of objects, surfaces or particles at very shallow or low
angles, so that light does not directly enter the optics.
Depth-of-Field—The in-focus range of an imaging system. Measured from the distance
behind an object to the distance in front of the object with all objects appearing in focus.
Diffused lighting—Scattered soft lighting from a wide variety of angles used to eliminate
shadows and specular glints from profiled, highly reflective surfaces.
Digital-to-Analog Converter—A VLSI circuit used to convert digital computer processed
images to analog for display on a monitor. DAC is the acronym.
Digital Imaging—Conversion of a video picture into pixels by means of an A/D converter
where the level of each pixel can be stored in a computer.
Digital Signal Processor (DSP)—A VLSI chip designed for ultra high speed arithmetic
processing. Often imbedded in a vision engine. TI's TMS320C40 is the industry standard.
Discrete I/O—Inputs and outputs characterized by discrete signal transitions from one
voltage level to another so that digital switching can occur.
DMA—Direct Memory Access. A capability provided by some computer bus architectures
that allows data to be sent directly from an attached device (such as a disk drive) to mem-
ory.
DSP—Digital Signal Processing
Dynamic Range—The difference between the minimum and maximum thresholds of dis-
cernible images; the amount of usable signal.
Edge Enhancement—Image processing method to strengthen high-spatial frequencies in
the image.
EPROM—Erasable, programmable, read only memory.
Embedded Memory—Onboard memory device such as EPROM or flash.
End of Read Cycle—The time or condition at which the reader stops expecting symbol
information to decode.