Ositech comm Trumpcard Data/Fax Modem - Manual (Page 56)

4 - 24 Trumpcard 14400/28800 Modem
Section Four
&Tn — Test and Diagnostic
Parameters 0, 1, or 3 through 8
Default 4
Selects the test command. Test commands must be initiated in the
command mode with asynchronous operation in the Direct mode selected
(&Q0) at a speed of less than 14400 or 28800 (28800 version only).
A telco line connection must be established prior to initiating digital
loopback tests. If these conditions are not met, the modem issues the
ERROR result code. If local analog loopback is initiated while the modem
is connected, the modem disconnects before performing the test.
An initiated test is active for a period of time specified by register S18 (test
timer) before returning to the command mode. If S18 is zero, the test
aborts when the user issues the &T0 command.
Examples
AT&T0 End test in progress. The escape sequence (+++)
must be issued to return the modem to the
command mode prior to sending this command.
Subsequent issuing of the O command while in the
command mode will cause the local and remote
modems to return to normal data mode operation if
the interrupted test was digital loopback.
AT&T1 Initiates local analog loopback. This test verifies the
working condition of the path between the local
communications software and the local modem. The
characters received from the communications
software are looped back by the modem.
AT&T3 Initiates remote digital loopback locally. The
characters received from the remote modem are
looped back to the remote modem by the local
modem. This test verifies the working condition of
the path from a remote modem, through a local
modem, and back to the remote modem.
AT&T4 Allows the modem to respond to a request from a
remote modem for a remote digital loopback test.
AT&T5 Prohibits the modem from granting a request from a
remote modem for a digital loopback test.