20
2-WIRE SHORT-RANGE DSL LINE DRIVER (HDSL WITH V.35 OR X.21)
• ER: blinks ON/OFF after a 511/511E test has timed out. See
Section 5.3
for
more information.
ER flashes once to indicate that a CRC error has occurred (during normal
operation) or bit errors have occurred (during 511/511E tests).
Only at power up, ER blinks once every 200 ms if the DTE Rate is set to
unsupported settings.
• TM: glows yellow to indicate that the Line Driver has been placed in Test
Mode. The unit can be placed in test mode by the local user or by the remote
user. The TM LED will flash for 400 msec when a valid packet is received from
the Managed Micro Rack SNMP/HTTP Card (part number RM261C-SNMP).
5.3 Test Modes
The Line Driver offers two proprietary loopback test modes, plus a built-in V.52
BER test-pattern generator to evaluate the condition of the modems and the
communication link. These tests can be activated physically from the front panel or
via the DTE interface.
5.3.1 O
VERVIEW
Figure 5-2 shows the major elements used in the loopback and pattern tests
available in the Line Driver. Each block has several functions. Following Figure 5-2
are descriptions that show how the elements are used during test modes.
Figure 5-2. The major elements used in loopback and pattern tests
in the Line Driver.
Framer
Processor
Processor
Framer
Pattern
Gen./Det.
Pattern
Gen./Det.
Loop
Control
Loop
Control
Line
