Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 141)

Half-Duplex Protocol
Chapter 11
11Ć14
Figure 11.5 shows a message transfer in which the BCC was invalid.
After a timeout, the message is retransmitted. After the retransmission the
response is DLE ACK.
Figure 11.5
Message Transfer with Invalid BCC
Not Full
OK
xxxx
xxxx
SINK MASTER LINK SLAVE SINK
1005–I
DLE ACK
DLE STX ??? DLE ETX BCC
SOURCE/ SOURCE/
DLE SOH STN
DLE STX xxxx DLE ETX BCC DLE SOH STN
(Timeout)