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Operation
INS (In Service) - Nomally lit constantly
after the DSU completes its power-up
sequence; terminal interface or SNMP
application can command this LED to
blink as an identifier for service personnel.
SD (Send Data) - Lit when the DSU is in
data mode and a space is detected in
the transmit data.
BPV (Bipolar Violation) - Lights when
incoming siganl at the DSU network
interface does not alternate signal
states to represent marks.
OOF (Out-Of-Frame) - Lit when the DSU
network interface is experiencing an out
of frame condition.
TM (Test Mode) - Lit when the DSU is
performing any type of test.
Blinks to indicate detected errors during
a Self-Test.
Figure 3-1
3-2
INS
L
I
N
E
SD
BPV AIS
OOF NS
TM
T1
CH
RL
M
O
N
553
Front Panel Indicators
SpectraComm 553 Fractional T1 DSU
Installation and Operation Manual
Controls and Indicators
ON
ON (Power On - Lit while power
is applied to the DSU.
I
N
O
U
RSP (Response) - Lit while the DSU
T
is transmitting a response to a
RSP
network controller command.
RD
RD (Received Data - Lit when the DSU
is in data mode and a space is detected
EQ
in the receive data.
EQ (Equipment) - Lit when the DSU is
equipped with the optional Cascade
Interface card.
ALM
AIS (Alarm Indication Signal) - Lit when
the DSU is receiving AIS (all ones) from
the network.
NS (No Signal) - Lit when the DSU does
not detect a network signal.
ALM (Alarm) - Lit when the DSU is
experiencing and alarm condition.
TX
RX
076R155-000
Issue 7
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