Simplex Sealing Current Information; Loopback Design Description - ADC HiGain HRU-402 User Manual

Product Overview
The HRU-402 List 3 must be locally powered with a -20V to -70V local
power supply with 250mA output current capacity (5.0 W).
A Teltrend© WPS-2005 Wall-Mount Power Supply (-48V and 250 mA) is
capable of powering two HRU-402 units. The 2005 provides spade lugs to
access its -48V output.
You can reach Teltrend at: 1 (800) TEL-TREN.
The HRU-402 supports up to five span applications.

Simplex Sealing Current Information

The HRU-402 can source from 30 mA (short loop) to 20 mA (long loop) of
simplex sealing current towards the upstream unit over the two HDSL pairs.
The SCURR (S1) switch, located on the printed circuit board at the back of
the unit, allows this sealing current to be enabled (ON) or disabled (OFF). See
"Panel Circuit Board Option" on page 8
The simplex sealing current flow is blocked if it is used with HDU-451
List 1, 2, 3 or 3B doublers. These doublers are only compatible with the
metallic sealing current of earlier remote units. To provide a path through
which the simplexed sealing current can flow, the following doublers must be
used with the HRU-402:
• HDU-451 List 4, 4B
•
HDU-437, HDU-439 List 1 or List 1B
•
HDU-409, HDU-404, and HDU-407

Loopback Design Description

Loopbacks permit you to perform isolated diagnostic tests at specific points
of the circuit. The transmitted signal is returned to the sending device after
passing through a data communications link or network. This allows you to
compare the returned signal with the transmitted signal and to determine if
there is a problem with the circuit. Ideally, personnel performing loopback
testing are in direct communication with each other in order to correlate
messages displayed at both the HRU and HLU during the test.
12
for further information.
November 5, 1998
150-402-100-03
HRU-402 List 1 and List 3