Rockwell Automation 1785-LTx,D17856.2.1 Classic PLC-5 Programmable Controllers Users Manual - Manual (Page 53)

Assigning Addressing Modes,
Racks, and Groups
Chapter 4
4-11
When assigning remote I/O rack numbers, use the following guidelines:
Limit the number of remote I/O rack numbers to those that your PLC-5
processor can support.
The PLC-5 processor and the 1771-ASB adapter module automatically
allocate the next higher rack number(s) to the remaining I/O groups of
the chassis. For example, if you select 1/2-slot addressing for your
processor-resident local chassis and you are using a 16-slot (1771-A4B)
chassis, the processor will address racks 0, 1, 2, and 3 in this chassis.
BlockĆTransfer Module Racks Using 1/2ĆSlot Addressing
To address a block-transfer module in a 1/2-slot I/O group, use the
assigned rack number, the lower assigned I/O group number of the slot(s)
in which the module resides, and 0 for the module number (Figure 4.4).
Figure 4.4
Example BlockĆTransfer Module Address Using 1/2ĆSlot Addressing
0–3 4–7 0–3 4–7 0–3 4–7 0–3 4–7
This example is valid for a singleĆslot
BT module only.
I/O Group
Number
Rack 0 Rack 1 Rack 2 Rack 3
Rack = 2
Group = 4
Slot = 0