22
2-WIRE SHORT-RANGE DSL LINE DRIVER (HDSL WITH V.35 OR X.21)
Table 5-1. Test mode timing.
Item
Elapsed Time (seconds)
Startup
50
Data Mode
4
511/511E Generator Enabled
60 (The generator will stop after 45
seconds.)
Remote End of an RDL
60
511/511E Timeout
45 (The pattern generator will automatically
turn off after 45 seconds. The ER LED will
flash until you turn off the 511/511E switch.)
Symbol Indicators
This symbol designates the origination or the termination of a data path. The
direction of the arrow connected in Figures 5-3 through 5-9 distinguishes the two
data paths.
This symbol designates an invalid data path. If there is data present, it should
be ignored.
5.3.3 L
OOPS AND
P
ATTERNS
The following section describes the Test Modes used in the Line Driver. At the
bottom of each test mode, a figure is included to show the data path.
Local Loop
There are two different modes of operation for a local loop depending on the
status of the units at the time that the local loop is initiated. If the units are not
linked (NS LED on) and the local loop is initiated—either by the front-panel
switch or the DTE interface—the unit will enter mode 1. If the units are linked (NS
LED off), then the unit will enter a mode 2 local loop.
A mode 1 local loop is shown in Figure 5-3. When the local loop is initiated, either
by the front-panel switch or the DTE interface, the loop will be activated within the
local processor. The data present at the local DTE interface will be looped back to
the local DTE by the loop control block within the processor. Any data present on
X
