DataComm V.34 PL, Operation Manual

Page: 43 / 56

Tests Remote Digital Loopback with Self-Test
060R115-000 DataComm V.34 PL Modem 4-7
Issue 1 Installation and Operation
Remote Digital Loopback with Self-Test
Remote Digital Loopback with Self-Test, illustrated below, is controlled at the local end. It can be
commanded from the front panel. This command can only be entered after the call is established
and both ends are in the data mode. The test causes the local modem to generate a pattern that is
transmitted across the telephone line to the remote modem's receiver, looped through to the remote
modem's transmitter, and sent back across the telephone line to the local modem's receiver for
analysis. The pattern is made up of alternate ones and zeros for 2400 bps. For all other speeds the
modem generates a 511 test pattern. The number of errors is displayed on the screen. This test
checks both modems and the telephone line.
Table 4-5 Remote Digital Loopback with Self-Test
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, then press ST.
Modem
transmitter
DTE
Communications
line
Remote loopback
DTE
LOCAL MODEM
REMOTE MODEM
Modem
receiver
Modem
receiver
Modem
transmitter
Self-test pattern receiver
Self-test pattern generator
For remote loopback, the local DTE or terminal is disconnected from
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 modem will accept Remote Digital Loopback commands.
3. To start the test, press RDL, then press ST.
4. TM flashes and the LCD displays the names (RL and ST) while it is setting up the test, TM lights
and the LCD displays four digits of the error count (0000 to 9999) while the test is running.
5. When the timer (S-Register 18) times out, the test expires.
6. To end the test, press AL, RDL or DL.
LOCAL
V.34 PL
TR SD RD MR RS CS CO GD TM ALM OH
AL ST RDL DL SEL RST
ADV
REMOTE