ZyXEL Communications omni series user manual Power-on Self-test, Isdn Loopback test AT&T9

∙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