Telenetics MIU14.4, Установка, эксплуатация и диагностика

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MIU Installation, Operation & Diagnostics Edition: March 30, 1998 Page 20
&T2 NO FUNCTION
&T3 PERFORM LOCAL DIGITAL LOOPBACK (See Figure 3)
The modem must be in the command state with connection established
when this command is issued, otherwise an ERROR result code occurs.
The AT&T3 command establishes a loopback of received data, after
demodulation, and sends it back to the distant end. The modem is
configured for local digital loopback, DSR is turned off (if &S1 is in
effect), the test timer is started with the value in S18, and an OK result
code is sent to the DTE. If S18 contains a 0, the test must be terminated
by a &T0, H0, or Z command. The latter two result in the modem going
on hook. If S18 does not contain 0, the test is terminated after the
number of seconds stored in S18.
RESULT CODE DESCRIPTION
OK After 2 second delay
ERROR If any other self test is active (&T1,
&T6, &T7 or &T8) or if in idle state.
When test is terminated.
&T4 GRANT REMOTE DIGITAL LOOPBACK (RDL) REQUESTS
When in the on-line state, the modem will honor a remote digital
loopback request from a distant modem if it occurs. This will result in an
ERROR if the command is given while any V.54 test is active (&T1,
&T3, &T6, &T7 or &T8).
NOTE: There are data patterns that may cause a Remote Digital
Loopback conditions. Care should be given to the type of data being
received so that no RDL modes will be initiated.