DataComm V.34 PL, Operation Manual

Page: 41 / 56

Tests Remote Digital Loopback
060R115-000 DataComm V.34 PL Modem 4-5
Issue 1 Installation and Operation
Remote Digital Loopback
Remote Digital Loopback, illustrated below, is controlled at the local end. It can be commanded
from the front panel, or by the DTE's EIA pin 21. The loopback can be commanded only after a call
is established and both ends are in data mode. In this loop, the demodulator's descrambled received
data at the remote end is coupled to the remote transmitter input for transmission back to the local
end.
Table 4-4 Remote Digital Loopback
Step Front Panel
1. Establish data communications with a
remote modem.
2. Check with the remote attendant that the
remote modem will accept Remote Digital
Loopback commands.
3. To start the test, press RDL.
4. The modem flashes the TM LED and
displays the test name (RL) while it is set-
ting up the test, then lights the TM LED
and decimal point two while the test is
running. (If the remote modem initiated the
test, the local modem lights decimal points
three and four while the test is running.)
Modem
transmitter
DTE
Communications
line
DTE
LOCAL MODEM REMOTE MODEM
Modem
receiver
Modem
receiver
Modem
transmitter
For the remote loopback test, the remote DTE or
terminal is disconnected.
Send
dat
a
Received
data
Remote loopback
V.34 PL
TR SD RD MR RS CS CO GD TM ALM OH
AL ST RDL DL SEL RST
ADV
1. Establish data communications with the remote modem.
2. Check with the remote attendant that the remote modem will accept
Remote Digital Loopback commands.
3. To start the test, press RDL.
4. TM flashes and the LCD displays the test name (RL) while it is setting up the test,
then TM lights, and decimal point two appears on the LCD while the test is running.
5. Enter data at the local DTE. Compare data that was entered at the DTE with the data
that is looped back and displayed by the DTE.
6. To end the test, press AL, RDL or DL.
V.34 PL
TR SD RD MR RS CS CO GD TM ALM OH
AL ST RDL DL SEL RST
ADV
LOCAL
REMOTE