Rockwell Automation Publication ICSTT-RM448M-EN-P - February 2021 59
Chapter 4 Before You Begin
Figure 12 - Connecting Base Units with Expansion Cables
The expansion bus accessed from the right hand edge of the T9100 processor
base unit is designated I/O Bus 1, while the bus accessed from the left hand
edge is designated I/O Bus 2. The module positions (slots) in the I/O base units
are numbered from 01 to 24, the left most position being slot 01. Any individual
module position within the controller can thus be uniquely identified by the
combination of its bus and slot numbers, for example 1-01.