Rockwell Automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command - Manual (Page 70)

4–16 Using Full-duplex Protocol to Send and Receive Messages
Publication 1770Ć6.5.16 - October 1996
Message Transfer with Timeout and ENQ for the Reply
In this transfer:
•
the message is successfully transmitted on the network
•
the receiver sends a reply from the network but the transmitter
sends back a DLE ACK that is corrupted
•
the receiver times out waiting for the DLE ACK and sends a DLE
ENQ
•
the transmitter sends back a DLE ACK
xxxx
not full
OK
OK
xxxx
xxxx
DLE STX xxxx DLE ETX BCC/CRC
DLE STX xxxx DLE ETX BCC/CRC
DLE ACK
Source Transmitter Link Receiver Sink
command
reply
(sometime later ...)
DLE ACK
not full
DL???CK
DLE ENQ
(Timeout)