38
ALM
(Alarm) glows red to indicate that one of several alarm
conditions exist. These conditions may be local alarms or
remote alarm conditions. Alarms may occur due to:
• Loss of Synchronization
• Loss of Frame
• AIS (Blue Alarm)
• RAI (Yellow Alarm)
ERR
(Error) flashes to indicate errors. There are several flash-
ing patterns to indicate the type of error.
• Invalid Switch Configuration: It is possible to request
more bandwidth than is possible. For instance, if you
set the starting channel to 12, and you select a number
of timeslots exceeding 13, the unit will not be able to
satisfy your request. In that case, the ERR LED will
flash once a second (fi second on, fi second off). When
the unit detects an invalid setting, it will ignore the set-
ting and default to a full T1 (bandwidth = 24 channels,
starting channel = 1). This will continue until you set the
switches to a valid setting. The invalid switch configura-
tion condition overrides other error conditions.
• V.52 Test Patterns: When sending a test pattern, the
LED will remain lit if the unit does not receive the identi-
cal pattern. When it receives the correct pattern, the
LED will turn off. If error insertion is on, the LED will
blink once a second if everything is operating properly.
• Errored Second: In ESF or SF framing, if the unit
detects a frame error, the ERR LED will flash briefly
once a second.
• Framing Mismatch: the ERR LED flashes briefly once
a second when framing modes are mismatched.
• Loss of Signal: When there is no signal at the network
interface, the ERR LED will flash briefly once a second.
TST
The test indicator LED blinks with a specific pattern
depending on the type of test mode.
• V.54 Local Analog Loopback: LED blinks on briefly
• V.54 Remote Digital Loopback: LED blinks off briefly
• CO Initiated Loopbacks: LED blinks off briefly
• Sending V.52 Test Pattern: LED stays on
• Sending V.54 Loopback Pattern: LED stays on
PWR
(Power) glows green to indicate that the unit is receiving
power.
5.2 LOOP (V.54 & TELCO) DIAGNOSTICS
The Model 2710A offers three V.54 loop diagnostics and is com-
patible with two Telco loop diagnostics. Use these diagnostics to test
the CSU/DSU and any communication links. These tests can be acti-
vated via the software control port (See Section 3.2.3 System
Diagnostics) or via signals on the serial port interface.
5.2.1 Operating Local Loopback (LL)
The Local Loopback (LL) test checks the operation of the local
Model 2710A, and is performed separately on each unit. Any data
sent to the local Model 2710A in this test mode will be echoed
(returned) back to the user device (i.e., characters typed on the key-
board of a terminal will appear on the terminal screen).
To perform a LL test, follow these steps:
1.
Activate LL. This may be done in one of two ways:
a. Enter Local Loop from the System
Diagnostics/Statistics menu and toggle the [Spacebar]
until “LL” appears next to the
Local Loop option.
b. Activate the “LL” signal on the DTE. If you are not sure
which lead is the “LL” signal, please refer to Appendix D.
2.
Verify that the data terminal equipment is operating properly
and can be used for a test.
3. Perform a V.52 BER (bit error rate) test as described in
Section 5.3.3. If the BER test equipment indicates no faults,
but the data terminal indicates a fault, follow the manufactur-
er’s checkout procedures for the data terminal. Also, check
the interface cable between the terminal and the Model
2710A.
5.2.2 Operating Remote Digital Loopback (RL)
The Remote Digital Loopback (RL) test checks the performance of
both the local and remote Model 2710A, as well as the communication
link between them. Any characters sent to the remote Model 2710A in
this test mode will be returned back to the originating device (i.e, char-
acters typed on the keyboard of the local terminal will appear on the
local terminal screen after having been passed to the remote Model
2710A and looped back).
a
a
37
