Windows Marketplace V.90 - Manual (Page 48)

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AT Commands for Testing and Debugging
The following commands are to be used for testing and debugging only and are
not meant for general use.
&Tn Self-Test Commands
This command allows the user to perform diagnostic tests on the modem. These
tests can help to isolate problems when experiencing periodic data loss or random
errors.
&T0: Abort. Stops any test in progress.
&T1: Local analog loop. This test verifies modem operation, as well as the con-
nection between the modem and computer. Any data entered at the local
DTE is modulated, then demodulated, and returned to the local DTE. To
work properly, the modem must be off-line.
&T3: Local digital loopback test.
&T6: Remote digital loopback test. This test can verify the integrity of the local
modem, the communications link, and the remote modem. Any data en-
tered at the local DTE is sent to, and returned from, the remote modem. To
work properly, the modems must be on-line with error control disabled.
Result Codes:
OK n = 0
CONNECT n = 1, 3, 6
ERROR Otherwise
&&C Write to/Read from DSP Register
AT&&C, writes the value to DSP register at location .
AT&&C reads from location .
&&L Line-to-Line Loopback
This command provides a loopback for line-to-line.
&&R Write to/Read from DSP RAM Location
AT&&R, writes the value to DSP RAM location .
AT&&R reads from location .