Rockwell Automation 57C570 AutoMax PC3000 User Manual - Manual (Page 62)

4Ć4
Table 4.1 Ć How Memory is Mapped into an I/O Address
Memory
unit:
Definition: Relation to scanner
module's I/O image area:
terminal
or point
A specific terminal on an I/O
module that occupies a
space in the PC3000's
memory.
The density of an I/O
module, i.e., 8Ćpoint,
16Ćpoint, 32Ćpoint, directly
relates to the amount of
memory (bits) the module
occupies in the scanner
module's input or output
image table. For example, a
16Ćpoint input module
occupies 16 bits in the
scanner module's input
image table.
I/O group I/O terminals that when
combined occupy 1 word in
the PC3000's input image
table and 1 word in the
PC3000's output image
table.
16 input bits = 1 word in
scanner module's input
image table
and
16 output bits = 1 word in
the scanner module's
output image table
I/O rack The principal logical
addressing construct that
groups 8 input words and 8
output words into a unit. An
I/O rack should not be
confused with an I/O chassis,
which is the physical housing
of I/O modules.
I/O racks are numbered in
octal.
128 input bits and 128
output bits
or
8 input words and 8 output
words
or
8 I/O groups