Rockwell Automation 1771-ASB/E Remote I/O Adapter User Manual - Manual (Page 33)

3–3 Addressing Modes for Your Remote I/O
Publication 1771-UM001A-US-P - February 2000
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.
I/O Module Combinations
The combination of I/O modules you can use depends on the
addressing method and I/O chassis you select.
Table 3.A lists acceptable I/O module combinations with 2-slot
addressing.
Table 3.A
I/O Module Combinations With 2Ćslot Addressing
I/O Chassis
Series
I/O Module CombinationsPer I/O Group
Data Table BitsUsed
Input Image Table Output Image Table
A, B 2 8Ćpointinputmodules 16 0
2 8Ćpointoutputmodules 0 16
1 8Ćpointinputand outputmodule 8 8
1 8Ćpointinputand 1 block transfer outputmodule 16 8
1 block transfer and 1 8Ćpoint output module 8 16
2 block transfer modules 16 16
B or later only 1 16Ćpointinputand outputmodule 16 16
1 16Ćpointand 1 8Ćpointoutputmodule 16 8
1 8Ćpointinputand 1 16Ćpointoutputmodule 8 16
2ĆSlot Addressing