Rockwell Automation 1747-SN Remote I/O Scanner - Manual (Page 19)

Publication 1747-UM013B-EN-P - January 2005
Overview 1-11
Guidelines for Configuring Complementary I/O
When you configure your remote system for complementary I/O,
follow these guidelines:
• You can place an output module in the primary chassis opposite
another output module in the complementary chassis; they use
the same bits in the output image table. However, we do not
recommend this placement of modules for redundant I/O.
• You cannot use complementary I/O with a chassis that uses
32-point I/O modules and 1-slot addressing or 16-point I/O
modules with 2-slot addressing.
• Do not place an input module in the primary chassis opposite
an input module in the complementary chassis; they will use the
same bits in the input image table.
ATTENTION
If the logical rack numbers are not properly
assigned, unpredictable operation of both ASB
modules results. No ASB module errors occur. Refer
to your ASB module user manual for specific
information on setting the address of the
complementary chassis. (For example, in the
1771-ASB manual the addresses for the
complementary chassis are referred to as
complementary chassis 0-3.)