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Diagnostic Command.
TA Reset.
Power-on Self-test
At each power-up or upon a reset command from the panel, the TA
will test the ROM code checksum, system RAM memory, EEPROM,
digital circuits and analog circuit calibrations.
The LNK LED will light up for half a second to indicate the success
of the TA's power on self-test. After completing a successful self test,
the LNK LED will become the normal physical layer (layer 1) active
indicator.
ISDN Loopback test (AT&T9)
The AT&T9 command will invoke an ISDN loopback test
connection. The loopback point is in the S/T interface chip (Siemens
2086 chip) or the U interface chip (Siemens 2091 chip) just behind
the line transformers, thus it checks almost every part of the ISDN
TA and RS-232 cable except the passive front-end of the ISDN S/T
or U interface.
During this test, data from the terminal or computer is sent through
the DTE interface to the ISDN TA's transmitter and is packetized to
the proper frame format according to the B channel protocol selected
and then loop-backed to the receiver, de-packetized, and sent
through the DTE interface back to the terminal or computer's screen.
The screen should show the data you have sent to the ISDN TA.
Loopback with Self-test (AT&T10)
The AT&T10 command will invoke an ISDN loopback connection
with self-test. The data is generated by the ISDN TA and will go
through the same path as the above Loopback Test does. The data
pattern is printable ASCII characters. You can see the result on the
screen. The loop backed data is compared with the transmitted data.
Should an error occur, the LNK LED will start to flash. Sending any
Diagnostics 101
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