Rockwell Automation 5370 CVIM Communications Manual User Manual

Page 197

Configurable Vision Input Module

Bulletin 5370 CVIM

Glossary

G–2

handshaking
Two–way communication between
two devices to effect a data transfer.
Handshaking operations are based on
a Data–Ready/Data–Received signal
scheme that assures orderly data
transfer.

hex
Abbreviated form of the word
hexadecimal.

hexadecimal
A base 16 numbering system.

hexadecimal numbering system
A numbering system using the
equivalent of the decimal number 16
as a base. Because only a single
character is allowed for each
absolute value, the hexadecimal
numbering system uses the 10
symbols of the decimal system for
values 0 through 9, and the first six
letters of the alphabet to represent
values 10 through 15 (a through F).
The positional significance of the
hexadecimal symbols is based upon
the progression of powers of 16. The
highest number that can be
represented in the units position is
15.

Image
A photographic picture, e.g., as being
picked up by a TV camera.
Mathematically, an image can be
described by a function of 2
variables f(x,y), usually defined over
a rectangular region. X and y are the
region coordinates, and f(x,y)
represents the gray scale value of the
point (x,y) in the region.

I/O
Acronym for Input/ Output.

left justified
A field of numbers (decimal, binary,
etc.) with no zeros or spaces to the
left.

lightpen
A hand held photosensitive input
device used to designate a location
on a display screen.

NAK
An abbreviated term for Negative
Acknowledgment. A control code
that indicates the previous
transmission block was not received
correctly.

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.

pixel
An element of a picture. In order for
a computer to analyze a picture, the
picture is broken up into a series of
picture elements called pixels. Each
pixel is assigned a brightness level
which is the average of the area in
the pixel. In computer vision
systems, the pixels is the smallest
area of resolution in a picture.