Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual User Manual
Page 177
Message Formats
Appendix A
AĆ15
Word Range Read
Use this read command with a word symbol, a file symbol plus a word
offset, or a block address as a starting address. This starting address must
point to a word in a file. This read command can read a block of data.
The function code is 1. A special case of this command is the
single–word read, where the number of bytes to read is only two bytes
(one word).
Command Format:
A. Word symbol address
DLE
SRC
C
0
S
TNS
MD
F
TS
TNS
STX
FNC PACKET
01
ASCII symbol
(8 characters max)
DLE ETX
BCC
00
W/F
00
SIZE
OFFSET
TOTAL
TRANS
00
DST
B. File symbol address plus word offset
DLE
SRC
C
0
S
TNS
MD
F
TS
TNS
STX
FNC PACKET
01
ASCII symbol
(8 characters max)
DLE ETX
BCC
00
W/F
00
SIZE
OFFSET
TOTAL
TRANS
00
DST
WORD
OFFSET
C. Logical Address
DLE
SRC
C
0
S
TNS
MD
F
TS
TNS
STX
FNC PACKET
01
PLC-3 logical symbol
(2-51 bytes)
DLE ETX
BCC
SIZE
OFFSET
TOTAL
TRANS
DST
Reply Format:
This is the same as he reply packet format for all reads.
A. Format when successful execution
DLE
C
S
TNS
MD TS
TNS
STX
DLE ETX
BCC
DATA - Max of 244 bytes or 122 words
DST SRC
4F