
Full-Duplex Protocol
Chapter 10
1019
Figure 10.11
Message
T
ransfer with T
imeout and ENQ
Not Full
DLE ACK
OK
xxxx
DLE ENQ
xxxx
SOURCE XMTR LINK RCVR SINK
10048–I
DL
DLE STXxxxxDLE EXTBCC
(Timeout)
???CK
In Figure 10.12, retransmission occurs when noise hits both sides of the
line. This type of noise destroys the DLE ACK while also producing
invalid characters at the receiver. The result is that the receiver changes
its last response to NAK and the transmitter retransmits the original
message packet.
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