Rockwell Automation 1770-KF2 Data Highway or Highway Plus Interface Module User Manual - Manual (Page 59)

Asynchronous Link Protocols
Chapter 4
4-16
Figure 4.8
Receiver for Full-Duplex Protocol
Yes
No
No
Yes
Yes
No
11699
RCVE
LAST = NAK
Receive
DLE
ENQ
?
Receive
Message
?
BCC/CRC
OK
?
LAST = ACK
LAST = NAK
Send DLE LAST