Technical Reference for ZyXEL omni.net series 

10-2 

Power-on Self-test 

At each power-up or after reset command from the panel, the omni.net 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). This loopback checks almost every part of the omni.net 

ISDN TA and RS-232 cable, except for the passive front-end of the ISDN S/T interface. 

During ISDN loopback test, data from the terminal or computer is sent through the DTE interface to 

the omni.net's transmitter and is packaged to the proper frame format according to the B-channel 

protocol selected. Then the test data-packet are loop-backed to the receiver, unpacked, 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 omni.net and goes through the same path as with the above Loopback Test. 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 character through the DTE interface to the ISDN TA will discontinue the test. 

B1/B2 Loopback with Self-Test (AT&T11) 

The [AT&T11] string commands testing for the readiness of your ISDN line which uses one 

B-channel (B1) to place a call and the other B-channel (B2) to receive the call. Follow these 

instructions to make your test call: