Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 149)

Binary Command Language
Appendix A
A-21
If no force table has been created in processor memory, the processor
responds to a read I/O word command with a forces unavailable response
code. The data stored at the specified address follows this response code in
the data buffer. The following example response block shows a read I/O
word command when no forces exist:
STX
02
OSC
01
SIZ
03
RSP
03 61
DAT
1C
ETX
03
CHK
89
The data bytes store:
lower byte of the data word (61 hex)
upper byte of the data word (1C hex)
If any other response code is returned, no data follows.
Writing Data
You can write data into processor memory either in individual words with
the write word command, or in blocks with the write block command. You
can also modify words in processor memory with the read-modify-write
command. The following two subsections explain the writing
data commands.
Write Word Command
Hex: 14
Parameters: Address that needs to be updated and the new data
Description: The following example command block writes new data into
address E3.1.5.0.0.0:
STX
02
ISC
01
SIZ
08
CMD
14 3C 05 00
ETX
03
CHK
FC
DAT
00 00 08 91
The data bytes store:
address mask (3C hex)
first address byte (05 hex)
second address byte (00 hex)
third address byte (00 hex)
fourth address byte (00 hex)
lower data byte (08 hex)
upper data byte (91 hex)