Northern Telecom DMS-100 Series Installation And Maintenance Manual page 95

0
0
0 * tip and ring loopback
0 Note: The
0 NT4X25AF /AG /AH /AK data units.
0 Operating company personnel can also perform a CO
0 on the DU as outlined in 297-2101-516, Line Maintenance Reference
0 Manual.
0
The local loopback
0 The DU loops back data at the
0 Characters entered
0 DTE.
0
To Perform a Local Loopback Test:
0 1. Set the Local Loop/Normal option switch, located under the DU
0 flip-up lid, to the Local Loop position.
0 lights.
0 2. Make sure the DTE power is on, then type a string of charac-
0 ters on the DTE keyboard.
0 back to the terminal, the DTE to DU connection is good.
0 3. Return the Local Loop/Normal switch to the
0 The Under Test LED turns off.
0 Note: You can not perform a local loopback test if there is no
0 TCM synchronization between the data unit and data line card.
0 To Perform a Local Loopback Test:
0 1. Press the Settings key.
0 2. Press the Alternate key.
0 3. Press the 0 on the numeric keypad until the Local Loop LED is
0 lit.
0 4. Press the Settings key again.
0 the Under Test LED lights.
0 5. Make sure the DTE power is on, then type a string of
0 ters on the DTE keyboard.
0 back to the terminal, the DTE to DU connection is good.
0 6. Press the Settings key.
0 7. Press the 0 on the numeric keypad until none of the Loopback
0 LEDs are lit.
0 8. Press the Settings key.
0 turn off.
0
tip and ring loopback test is only available on the
test checks the terminal-to-DU connection.
on the DTE keyboard are echoed back to the
The Settings LED lights.
The Alternate LED lights.
The Settings LED lights.
The Settings and
DTE interface towards
(NT4X25AA /AE /AN /AP /AX /AZ)
The Under Test
If the typed characters are echoed
(NT4X25AF /AH)
The Settings LED turns off and
If the typed characters are echoed
297-2121-226
VINTAGE 05.01
loopback test
the DTE.
LED
Normal position.
charac-
Under Test LEDs
5-5