ZyXEL U-336R User Guide - Page 145

Local Digital Loopback Test (AT&T3) This test will loopback the digital form data demodulated from the receiver to the input of the transmitter. During testing, all data received from the remote modem will be returned to the remote modem. This test is applicable when the remote modem does not provide V.54 Remote Digital Loopback capability. This test can be initiated by the local modem when the modems are on-line. Remote Digital Loopback Test (AT&T6) This test will request the remote modem to do a digital loopback. During testing, the local modem will send a remote digital loopback request to the remote modem according to V.54. If the remote modem supports V.54 and is programmed to grant this kind of request, it will resend all of the received data back to the local modem. The local terminal or computer will receive all of the data it sends out. This test is applicable when the remote modem and local modem both provide V.54 Remote Digital Loopback capability. This test can be initiated by either modem when the modems are on-line. Remote Digital Loopback with Self-test (AT&T7) This test generates data from the modem itself instead of input data from the RS-232 interface. The data will go through the same path as it would with the Remote Digital Loopback Test. In asynchronous mode, the pattern consists of printable ASCII characters. You can see the results on the screen. In the synchronous mode, the pattern is made up of scrambled binary 1, and the Throughput Meter of the initiated modem will change to a Bit Error Rate Meter. The left reader displays accumulated bit errors and the right reader displays accumulated bits sent. This test can be initiated by either modem when the modems are on-line. Diagnostics & Troubleshooting 131