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o Step1:
Preparation of interfaces
for TX. The
two grounding
circuits,1(shield) and 7
(ground)
are active b/w the two devices
o Step 2 ensures that all four devices are
ready for TX. First the sending DTE activates
pin
20 and sends a Dte ready message to its DCE . DCE answers by activating pin6
.
Same
sequence is performed by remote computer
o Step3: sets up the physical connection
b/w the sending and the receiving modems.
o First the DTE activates pin 4 and sends
its DCE a request to send message. The DCE
transmits
a carrier signal to the idle receiving modem
o When
receiving modem detects
the carrier signal,
it activates pin
8, telling its
computer
that a TX is about to begin .
o After
tx the carrier
signal, sending DCE
activates pin 5
sending its DTE
a clear to
send
message. The remote computer and modem
do the same step
o Step4: Data transfer procedure
o Initiating computer transfers its data
stream to its modem over circuit 2accompanied
by
the timing pulse of circuit 24.
o Modem converts digital data to an analog
signal and sends it over the network
o Responding modem
retreives the signal,
converts it back
to digital and
passes it to
DTE
via circuit 3 and timing pulse of 17
o Step5:
Once both computers
have completed their
transmission, both computers
deactivate their
request-to-send circuits ,
modems turn off
their carrier signals,
their
received
line signal detectors and their clear to send circuits
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