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SW1-8: Enable/Disable Loop Tests from DTE
Use Switch SW1-8 to allow Model 2701 to enter loopback tests when the
DTE raises the appropriate loop request pin.
Switch SW2-1 Line Coding: HDB3 (default)
Use Switch SW2-1 to control the Network Line Coding options. Set these
options to be the same as the Line Coding given to you by your Service
Provider. If you are using two Model 2701s together as short range
modems, set both units to HDB3.
Options:
HDB3, AMI
HDB3
In this line coding, the transmitter substitutes a deliberate bipo-
lar violation when excessive zeros in the data stream are
detected. The receiver recognizes these special violations and
decodes them as zeros. This method enables the network to
meet minimum pulse density requirements. Unless AMI is
required in your application, HDB3 should be used whenever
possible.
AMI
Alternate Mark Inversion defines a pulse as a “mark,” a binary
one, as opposed to a zero. In an E1 network connection, signals
are transmitted as a sequence of ones and zeros. Ones are
sent as pulses, and zeros are sent as spaces, i.e., no pulse.
S1-8 Setting
Off Response to DTE Loopback Request Enabled
On Response to DTE Loopback Request Disabled
Position Function Factory Default Selected Option
SW2-1 Line Coding Off HDB3
SW2-2 CRC-4 multiframe Off Disabled
SW2-3 Data Inversion Off Data Not Inverted
SW2-4 V.54/CSU select Off V.54 RDL loop
SW2-5 FPS enabled Off Enabled
SW2-6 V.54 Response On Disabled
SW2-7 Not Used N/A N/A
SW2-8 Not Used N/A N/A
SW2-1 Line Encoding
Off HDB3
On AMI