Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 161)

Network and Application Layer Protocols
Chapter 12
12Ć14
The symbolic addressing format applies to PLC–3 type commands
(Table 12.A, appendix A) transmitted to the 1775–KA module. You can
use this addressing format whenever you have defined a system symbol to
represent a symbolic address at the PLC–3 station that is to receive the
command message. Figure 12.6 shows this format for PLC–3 symbolic
addresses. Always enter zeros for the first and last bytes of the symbolic
address field. Between these zero delimiter bytes, enter the ASCII codes
for the 1 to 8 characters of the symbol name. If the symbol name is more
than 8 characters long, enter only the first 8 characters.
Figure 12.6
Format for PLC-3 Symbolic Address
~ ~~
~ Etc.
0 (zero)
First character
Second character
Eigth Character
0 (Zero)
10067-I
The physical addressing format applies only to PLC–3 physical read and
physical write commands. Physical word addresses run in sequence,
starting with 0 (zero) for the first word of PLC–3 memory. Physical
addresses occupy 2 words (4 bytes), in the following bit format:
A24 A23 A22 A21 A20 A19 A18 A17
0 0 0 0 0 0 0 0
A8 A7 A6 A5 A4 A3 A2 A1
A16 A15 A14 A13 A12 A11 A10 A9
First byte
Second byte
Third byte
Fourth byte