Manual

Addressing Modes for Your I/O 3–3
Publication 1771-6.5.123 – May 1996
Using 2-Slot Addressing
Definition: The processor addresses two I/O module slots as one I/O
group.
Concept: Each physical 2-slot I/O group is represented by a word in
the input image table and a word in the output image table. Each
input terminal corresponds to a bit in the input image table word and
each output terminal corresponds to a bit in the output image table
word.
The maximum number of bits available for one 2-slot I/O group is
32: 16 bits in the input image table and 16 bits in the output image
table. The type of module you install (either 8 or 16-point I/O)
determines the number of bits in the words that are used.
You select 2-slot addressing by setting switches 5 and 6 of the I/O
chassis backplane switch assembly to the OFF position as shown in
Chapter 2.
I/O Module Combinations
The combination of I/O modules you can use depends on the
addressing method and I/O chassis you select.
NO TAG lists acceptable I/O module combinations with 2-slot
addressing.
T able 3.A
I/O Module Combinations W ith 2-slot Addressing
I/O Chassis
Series
I/O Module Combinations Per I/O Group
Data T able Bits Used
Input Image Table Output Image Table
A, B 2 8-point input modules 16 0
2 8-point output modules 0 16
1 8-point input and output module 8 8
1 8-point input and 1 nondiscrete module 16 8
1 nondiscrete and 1 8-point output module 8 16
2 nondiscrete modules 16 16
B or later only 1 16-point input and output module 16 16
1 16-point input and 1 8-point output module 16 8
1 8-point input and 1 16-point output module 8 16