Rockwell Automation 1747-ASB Remote I/O Adapter - Manual (Page 61)

Publication 1747-UM006B-EN-P - June 2003
Configuration 4-7
In addition, the 1747-ASB modules do not have to have to be
controlling the same number of slots or type of chassis.
Primary and complementary chassis cannot have the same logical rack
number. The logical rack numbers must be assigned to the primary
and complementary racks as shown below:
The following example illustrates how I/O modules requiring two
words of the input or output image can leave unused image space.
Complementary I/O allows two chassis to overlap their input and
output images, creating one image within the scanner.
IMPORTANT
If a 1747-ASB module is configured as a primary
chassis and as the last chassis, a 1747-ASB module
error occurs. Only complementary chassis can be
configured as last chassis. For information
concerning last chassis selection, refer to page 4-19.
Primary Chassis
Logical Rack Number
(1)
(1) If a 1747-ASB module is configured as a primary chassis with a logical rack number greater than 7, a
1747-ASB module error occurs.
Complementary Chassis Logical Rack Number
Decimal Octal
0 8 10
8
1 9 11
8
2 10 12
8
3 11 13
8
4 12 14
8
5 13 15
8
6 14 16
8
7 15 17
8
ATTENTION
!
If the logical rack numbers are not properly
assigned, unpredictable operation of both 1747-ASB
modules results. No 1747-ASB module errors occur.
IMPORTANT
Some processors and/or scanners have configuration
limitations when using complementary I/O in the
addressing modes. Refer to the appropriate PLC or
scanner manual for more information.