Starting Your Processor
Chapter 5
5-12
Assigning I/O Rack Numbers
When you select 1-slot addressing, each slot is an I/O group. You still
assign one I/O rack number to eight I/O groups; therefore, in a 16-slot I/O
chassis you now have two I/O racks (Figure 5.9).
Figure 5.9
Assigning I/O Rack Numbers with 1Slot Addressing
01 23 45 67 01 23 45 67
13077
I/O group number
1771A4B I/O chassis using 1slot addressing.
assigned
I/O rack number 1
assigned
I/O rack number 2
In Figure 5.3, we showed how the 5-digit input or output instruction is
associated with a particular I/O module terminal. With two I/O racks you
use the instruction address to identify which rack you are
communicating with.
Figure 5.10 illustrates addressing two modules, each in the same I/O group
number but in different assigned racks of a single I/O chassis.
