Rockwell Automation 1771-ACNR15 CONTROLNET ADAPTER MODUL - Manual (Page 31)

3–7 Addressing Modes for Your I/O
Publication 1771-6.5.124 – August 1997
Using 1-Slot Addressing
Definition: The processor addresses one I/O module slot as one I/O
group.
Concept: The physical address of each I/O group corresponds to an
input and output image table word. The type of module you install
(8, 16, or 32-point) determines the number of bits in these words that
are used.
You select 1-slot addressing by setting switches 5 and 6 of the I/O
chassis backplane switch assembly as shown in Chapter 2:
•
switch 5 to the ON position
•
switch 6 to the OFF position
With 1-slot addressing, because 16 input AND 16 output bits are
available in the processor’s image table for each I/O slot, you can use
any mix of 8-point, 16-point or nondiscrete I/O modules in the I/O
chassis.
To use 32-point I/O modules with 1-slot addressing, you must install,
as a pair, an input module and an output module in 2 adjacent slots of
the I/O chassis beginning with I/O slot 0 (Figure 3.6). If you cannot
pair the modules in this way, one of the two slots of the pair must be
empty. For example, if I/O slot 0 holds a 32-point input module, I/O
slot 1 can hold an 8, 16, or 32-point output module (or a module that
uses the backplane for power only); otherwise, it must be empty.
Figure 3.6
Using 32-point I/O Modules with 1-slot Addressing
0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5
I/O I/O I/O I/O I/O I/O I/O I/O
Input/Output Pairs
I/O Chassis Slot Number
14973
Thirty-two-point I/O modules need 32 input or 32 output bits in the
processor’s image table. Because only 16 input and 16 output bits
are available for each I/O group, to address a 32-point I/O module,
the ControlNet adapter module uses the unused input or output word
associated with the adjacent I/O slot.