Overview
150-357-200-02, Issue 2
10
February 9, 1999
HXU-357 List 1
•
controls: operates and releases controls, including loopback and
switching.
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Simple Management Network Protocol (SNMP): supports both standard
and proprietary Management Information Bases (MIBs); supports
SNMP version I and MIB II.
Multiplexer / Demultiplexer Circuitry
The HXU-357 accepts up to 28 DS1 (data and clock) signals and multiplexes
them into an electrical DS3 clock and data signal. It also demultiplexes the
electrical DS3 clock and data signal into 28 DS1 (data and clock) signals. The
transceiver converts the NRZ signals to a bipolar drive for the coax cable.
The HXU-357 firmware controls multiplexer operation. The firmware allows
the local multiplexer to perform tests as well as initiate loopbacks on the
far-end multiplexer.
Memory
Resident software programming is permanently stored in three types of
memory: EEPROM, Flash RAM, and SRAM. Each can be upgraded from
1 MB to 2 MB.
In addition to the three memories mentioned above, there are four 16-bit
registers (two read registers and two write-parallel registers).
Clock Circuit
The microprocessor derives its clock source from a crystal oscillator
operating at 40 MHz divided down to 20 MHz. This provides the timing
references at the clock input for the HXU-357.
You can download the HXU-357 software over the Ethernet
connection or locally by a maintenance terminal connected to
the craft port of an HMU-319 List 7 or List 7A. This operation
is under software control. See
