Rockwell Automation 2755-DM9, -DM9E High Speed Decoder - Manual (Page 158)

Glossary
G–3
msec
Abbreviation for millisecond (1/1000
of one second).
multidrop
A term used to describe multiple
devices linked by a communications
network.
multiplexer
A device which sends two or more
signals over the same circuit.
N
NAK
An abbreviated term for Negative
Acknowledgement. A control code
that indicates the previous
transmission block was not received
correctly.
NEMA
Acronym for National Electrical
Manufacturers Association
No–Read
A conditon where a bar code is
expected but is not read.
numeric
A machine vocabulary that includes
only the numbers as contrasted to
alphanumeric which includes both
letters and numerals.
P
parity bit
A parity bit is added to a binary array
to make the sum of all the bits
always odd or always even; a
fundamental check.
Percent Good Reads
The number of successful reads per 100
attempts to read a particular symbol.
R
restart
Another term for rebooting the
software. Same function as turning
power on the decoder off then back
on.
S
scan
The search for a symbol or marks
which are to be optically recognized.
scan area
The area intended to contain a
symbol.
scan head
An electronic device that optically
converts printed information into
electrical signals.
self–checking
A bar code or symbol using a
checking algorithm which can be
applied to each character to guard
against undetected errors.
Non–self–checked codes may
employ a check digit or other
redundancy in addition to the data
message.
space
The lighter element of a bar code
formed by the background between
bars.