Rockwell Automation 1747-DCM,D17476.8 Direct Communication Module - Manual (Page 26)

Chapter 3
Addressing
3–2
PLC/Scanner Addresses
The three parts of the PLC address include the:
•
logical rack
•
logical group (I/O group)
•
bit
I = Input
O:017/10 I:023/10
02 = Logical Rack
3 = I/O Group
10 = Bit (octal)
O = Output
01 = Logical Rack
7 = I/O Group
10 = Bit (octal)
PLC Input Address PLC Output Address
The rack address refers to the logical rack assigned to the DCM in the PLC/
scanner I/O image table. It is selected using switches 1 through 6 of SW1 on
the DCM. This address does not need to match the physical slot address of
the DCM. Complete information about DIP switch selection is in chapter 4,
Module Configuration.
The I/O group address refers to the word in the PLC/scanner image table
that contains the referenced I/O data bit. The I/O group address does not
need to match the word address of the SLC I/O instruction.
The bit address is the bit within the word being addressed. Bits are
numbered 0–17 (octal) for the PLC and 0–15 (decimal) for the SLC. The
physical position of the bit in the PLC word must match the position of the
bit in the SLC word to address the correct bit.