Rockwell Automation 1747-ASB Remote I/O Adapter - Manual (Page 44)

Publication 1747-UM006B-EN-P - June 2003
3-8 Addressing
1-Slot Addressing Considerations
When the 1747-ASB module is configured for 1-slot addressing, you
can use 4, 8, 16 point, 32 point discrete and discrete combination,
discrete and block transfer specialty I/O modules.
Like 32 point modules (i.e., two input modules) cannot be installed as
a pair because both slots cannot use the same image location. For
example, if you use a 32 point input module that requires two words
of the image, the other module within the pair must be an output
module.
If the discrete mode is selected, specialty I/O modules with two words
or less of input and output image are discretely mapped such as the
1746-NIO4I. However, with a combination specialty module such as
the 1746-NIO4I, the adjacent slot must be empty. Specialty I/O
modules with more than two words of input or output image are
block transfer mapped such as the 1746-NI4, -NO4I, -NO4V, and -HS.
If the block transfer mode is selected, all specialty I/O modules are
block transfer mapped regardless of their image size.
The 1747-ASB module can block transfer map a maximum of eight
words.
When a module is installed in slot 1 that requires both
words of input image, slot 1 uses the input image normally
assigned to slot 2. Slot 2, therefore, cannot use any of its
input image. However, slot 2 can now use the output
image normally assigned to slot 1, because slot 1 is not
using it.
1 5 1 4 1 3 1 2 11 1 0 9 8 7 6 5 4 3 2 1 0
When a module is installed in slot 2 that requires both
words of output image, slot 2 uses the output image
normally assigned to slot 1 (if slot 1 is not already using
it). The lesser slot number has priority over the greater.
Group 0
Slot 1
Group 1
1 5 1 4 1 3 1 2 11 1 0 9 8 7 6 5 4 3 2 1 0
Group 0
Slot 2
Group 1
Decimal
Octal 7 0 10 17
Decimal
Octal 7 0 10 17
Slot 1
Paired
Slot 2
Paired
O
I = Input Module
= Output Module
I
O
I
O
Slot Pair
Input Image
Output Image