Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual User Manual
Page 170
Message Formats
Appendix A
AĆ8
Figure A.3
Typical monitor display and how it is interpreted
S
B
8N
N
A
K
N
U
U
E
X
D
L
E
X
D
L
A
K
X
S
U
L
D
>
{
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DLE STX
DST SRC
CMD STS TNS
FNC
DLE
ETX BCC DLE ACK
Monitoring a diagnosticc status command and reply acknowledgement.
Line monitor displays:
Examining the ASCII table shows that for the above message:
CMD = 6
STS = 0
FNC = 3
10070-I
∼
The basic command set includes those commands that can generally be
executed by any PC station on the communication link, regardless of the
type of PC controller at the station. In some cases, switch settings on the
station interface module can disable execution of a particular type of
command at that station. For more details, refer to the user’s manual for
the station interface module.
The basic commands are:
protected bit write
protected write
unprotected bit write
unprotected read
unprotected write
Protected Bit Write
Use this command to set or reset individual bits within limited areas of the
PC data table memory. Your access can be limited by memory access
rungs in the communication zone of the PC’s ladder diagram program.
The data field in this packet consists of 4–byte blocks, each of which
contains a 16–bit address field, a set mask, and a reset mask. Use the
ADDR field to specify the address of the byte to be modified in the PC
Basic Command Set