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Principles of Operation
The meanings of the eight MPU (microprocessor unit) activity monitoring LEOs are
as follows:
Mnemonic
TX
RX
MN
DL
MPU Activity in Progress
On when the LANIC is processing and transmitting a frame.
On when the LAN IC is process ing a frame that was rece i ved a t an
address which the LANIC recognized as its own.
On when the LANIC is monitoring all link activity, or is monitoring
activity sent to a particular address not its own.
On when the LANIC receives a command from the SPU (system processor
unit) to start downloading operating firmware.
Off when the SPU
commands the MPU to begin to execute the downloaded feature.
RO
On when ROM-resident firmware is being executed by the MPU.
Off
when downloaded firmware is being executed by the MPU.
Q
On when the MPU is quiescent.
During such times, it is checking
for activity that requires attention.
IT
On when
the MPU
is executing an
idle
test
of
internal
LANIC
circuitry.
During
idle
test, the MPU tests hardware on the LANIC
that
can
be
exercised
without
affecting
readiness to
process
frames.
The
idle
test
also
runs
before
the
node
becomes
operational on the link.
ST
On when the MPU is execut ing the ROM- res ident sel f-test,
wh ich
verifies proper operation of the LAN hardware subsystem.
When the
ST LED is lit, the other seven MPU activity LEDs are interpreted as
self-test progress and failure indicators, rather than according to
the mnemonics given above.
For details of the use of self-test,
see
Section
4 of
this
manual
and
the
LAN/3000 Diagnostio and
Troubleshooting Guide, part number 30242-90003.
The seven AUI activity LEDs are intended to be used as aids in determining activity on the network, and
whether the source of this activity is this node or some other node on the network. These seven LEDs
monitor the four functions shown below.
Mnemonic
DO
CL
Feb 85
3-14
Function Monitored
Data Out.
On when data is transferred from this LANIC to the Data
Out
AUr
pair.
CoL
1
is ion Detect.
On when a co
11
is ion is detected by the MAU on
thIs node.
Since the HP 30241A MAU detects collisions whether it
is
transmitting
or not,
the CL
indicator
comes
on
for every
collision that occurs on this coaxial cable.
The CL indicator does
not come on when the MAU sends an SQE heartbeat after transmission.
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