9
10
NOTE 1: When using the Model 2710RC as a high-speed short
range modem, one unit of the link must be configured in
Internal/External Clock mode, and the opposite end unit must be
configured for Network Clock mode.
If the ERR LED on the front of the unit is flashing (or on) it could
be an indication of a clocking problem. Double check your clock
mode settings and your Tx Clock Select (S2-2) and Tx Clock
Invert S2-3 settings.
Switch S1-8 Reserved
3.1.2 Switch S2
The chart below shows the default configurations for Switch S2. A
description of all S2 options follows this table.
Switch S2-1: RDL Type
Switch S2-1 selects the type of Remote Digital Loopback that the
2710RC will initiate when the RDL is initiated from this unit. The
2710RC will respond to both the V54 and the CSU loopback regard-
less of the setting of S2-1
S2-1
RDL Type
On
Initiate a V.54 RDL loop when selected
Off
Initiate a CSU loopback when selected
Switch S2-2: Tx Clock Select
Switch S2-2 selects the clock that is used to accept the Transmit
Data from the DTE interface. Standard DTE interfaces will transmit
data with respect to the External Clock. In some cases a DTE interface
will transmit with respect to the Transmit clock sent out from the
2710RC. Please review the information provided with your DTE equip-
ment for more information on its' operation. In most cases when there
are errors on the line only in the direction of the transmit data either
S2-2 or S2-3 can be changed to solve the problem.
S2-2
Tx Clock Select
On
Transmit data accept with respect to the transmit
clock from the 2710RC
Off
Transmit data accept with respect to the external
clock from the DTE (not valid when unit uses an
Ethernet rear card)
Switch S2-3: Tx Clock Invert
Switch S2-3 allows the user to invert the transmit clock originating
in the 2710RC. When S2-2 is set for transmit clock, it may be neces-
sary to invert the transmit clock to allow for cable delays.
S2-3
Tx Clock Invert
On
Transmit clock is inverted
Off
Transmit clock is normal
Switches S2-4 and S2-5: Line Build Out
Use Switches S2-4 and S2-5 to set the Line Build Out (LBO). The
Line Build Out varies the pulse shape and attenuation of the signal
sent to the network. The amount of Line Build Out depends on
NetLink™ T1’s distance to the last repeater. The telephone company
providing the service will advise on the amount of LBO necessary.
SW2-4
SW2-5
Function
Off
Off
0-133 ft (0dB)
On
Off
-7.5dB
Off
On
-15.0dB
On
On
-22.5dB
Switch S2-6 Through S2-8: Reserved
S2 SUMMARY TABLE
Position
Function
Factory Default
Selected Option
S2-1
RDL Type
On
S2-2
Tx Clock Select
On
S2-3
Tx Clock Invert
Off
S2-4
Line Build Out
Off
S2-5
Off
S2-6
Reserved
Off
S2-7
Reserved
Off
S2-8 Reserved
Off
V.54 RDL
Internal Clock
Normal
0dB
