Scanner I/O Image Concepts - Allen-Bradley 1747-SN User Manual

Scanner I/O Image
Concepts
Bit Number (decimal)
Rack 0 Group 0
Rack 0 Group 1
RIO
Rack 0 Group 2
Logical
Rack 0 Group 3
Rack 0 Group 4
Rack 0
Rack 0 Group 5
Rack 0 Group 6
Rack 0 Group 7
Rack 1 Group 0
Rack 1 Group 1
RIO
Rack 1 Group 2
Logical
Rack 1 Group 3
Rack 1
Rack 1 Group 4
Rack 1 Group 5
Rack 1 Group 6
Rack 1 Group 7
Rack 2 Group 0
Rack 2 Group 1
RIO
Rack 2 Group 2
Logical
Rack 2 Group 3
Rack 2
Rack 2 Group 4
Rack 2 Group 5
Rack 2 Group 6
Rack 2 Group 7
Rack 3 Group 0
Rack 3 Group 1
RIO
Rack 3 Group 2
Logical
Rack 3 Group 3
Rack 3
Rack 3 Group 4
Rack 3 Group 5
Rack 3 Group 6
Rack 3 Group 7
Bit Number (octal)
The scanner's I/O image consists of RIO logical racks and I/O
groups. A full RIO logical rack consists of eight input image and
eight output image words. (A word consists of 16 bits of data.) Each
word within an RIO logical rack is assigned an I/O group number
from 0 to 7.
You assign devices on the RIO link a portion of the scanner's image.
Devices can occupy a quarter logical rack (2 input and output
words), half logical rack (4 I/O words), three quarter logical rack (6
I/O words), or full logical rack. You may configure devices to start
at any even I/O group number within an RIO logical rack. More
than one physical device's (adapter) I/O information can reside in a
single logical rack. Also, by crossing logical rack boundaries a
device can consist of more than one logical rack.
Important:
Input Image Half of a Scanner's I/O Image
15 14 13 12
Word 0
Word 1
Word 2
Word 3
Word 4
Word 5
Word 6
Word 7
Word 8
Word 9
Word 10
Word 11
Word 12
Word 13
Word 14
Word 15
Word 16
Word 17
Word 18
Word 19
Word 20
Word 21
Word 22
Word 23
Word 24
Word 25
Word 26
Word 27
Word 28
Word 29
Word 30
Word 31
17 16 15 14
8 8 8 8
The illustration below shows only the input image
configuration of the scanner's I/O image. The output
image configuration is the same.
11 10 9 8 7 6
13 12 11 10 7 6
8 8 8 8 8 8
Overview
5 4 3 2 1 0
5 4 3 2 1 0
8 8 8 8 8 8
Publication 1747 6.6 - July 1996
1–7
Quarter Logical
Rack
Not Used In This
Example
Half Logical
Rack
Not Used In This
Example
Three Quarter
Logical Rack
Not Used In This
Example
Full
Logical
Rack