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Principles of Operation
The meanings of the eight MPU (microprocessor unit) activity monitoring LED's 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 LANIC is processing a frame that was received at 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 dO\.l/nloading 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.
a
On when the MPU is qu iescent.
Du ring such times, it is check ing
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
prop~r
operation of the LAN hardware subsystem.
When the
ST LED is lit, the other seven MPU activity LED's 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 LED's 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 LED's
monitor the four functions shown below.
Mnemonic
Function Monitored
DO
Data Out.
On when data is transferred from this LANIC to the Data
Out AUI pair.
CL
CoLlision Detect.
On when a collision is detected by the MAU on
this node.
Since the HP 28641A ThinMAU 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 SaE heartbeat after transmission.
11/85
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