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Introduction 53
Model 3088 Series User Manual 4 • Operation
Term (Green) [Models C and D]
The Term LED glows solid under the following circumstances:
• 3088/CA with V.35 interface: If the serial interface has asserted DTR
• 3088/D with the X.21 interface:
- Configured as DCE: Indicates that the “Control” signals have been asserted.
- Configured as DTE: Indicates that the “Indication” signals have been asserted
TM/ER (Red)
The TM/ER LED is used to indicate that a test mode is in progress or an error has been detected. It blinks
once every second while a test mode is starting. It glows solid while a test mode is in progress. It blinks once if
an error is detected either during a test mode, or in normal DSL operation.
LOS (Red) [Models K and T]
The LOS LED blinks once per second to indicate either framing errors or clock slips. Clock slips are often
caused by a mis-configured clock mode.
Test modes
The 3088 offers test modes in the form of loopbacks, PRBS pattern generators, and combinations of both.
This section discusses how the test modes work. The following 3088 models have toggle switches available on
the front panel for operating test modes:
• 3088/CAS/E
• 3088/DS/E
• 3088/KS/E
• 3088/TS/E
Figure 20. 3088/S Model Front Panel
Figure 21 is a block diagram of the Model 3088 with respect to test modes.
Figure 21. Model 3088 Block Diagram
Power
DSL
Link
TM/ERR
LOS
Test Modes
Local –
Normal –
Remote –
– 511E
– Normal
– 511
DSL
Framer
511 Pattern
Generator
511 BER
Meter
DSL
Framer
511 Pattern
Generator
511 BER
Meter
Line