Allen-Bradley PLC-5 User Manual page 50

4-6 Addressing I/O and Controller Memory
Input
Terminals
00
01
02
03
04
05
06
07
10
11
12
13
14
15
16
17
16-point I/O modules occupy 16 bits, an entire word, in
the image table.
Installing as a pair a 16-point input module and a
16-point output module efficiently uses the image table.
Publication 1785-UM012D-EN-P - July 2005
When planning your system design, consider the densities of the I/O modules
you are using and choose an addressing mode that most efficiently uses
controller memory.
Example of Efficient I/O Image Table Use.
Output
Terminals
00
01
02
03
04
05
06
07
10
11
12
13
14
15
16
17
Group 0
Define the addressing mode for each I/O chassis by setting the chassis
backplane switch assembly. For more information, see Appendix E.
2-slot addressing (2 I/O chassis slot = 1 I/O group = 1 input image
word and 1 output image word = 16 input bits and 16 output bits.)
Controller memory
Rack x
Output Image Table
Word #
0
1
2
3
4
5
6
7
17
Input Image Table
Word #
0
1
2
3
4
5
6
7
17
00 bits
00 bits