&T7 - Initiate RDL With Self Test
Command Line Format
AT [cmds] &T7 <CR>
Suffix Values
N/A
Default
N/A
Stored by &Wn
N/A
Displayed by &V
N/A
Description
The command is only valid if the modem is in the Online Command State,
the modulation is one of the QAM types that support full-duplex transmission,
and the speed is the same in both directions. The command is not valid for
any FSK modulation (e.g., V.21 and V.23).
The modem sends the remote digital loopback request signal to the distant
end. After the RDL acknowledgment signal is received from the distant end,
DSR is turned off (if &S1 is in effect), the Online State is entered, an
OK result code is sent to the DTE, and the test timer is set to the value
in S18.
While the test is active the modem sends a test message to the distant end
and counts the errors in the received (looped back) signal. The modem stays
in the Online Command State during the test.
When the test is terminated (except by a loss-of-carrier), the modem sends
the release signal to the distant end, as in &T6, and reports the three-digit
error count to the DTE. The information text is followed by an OK result
code. See the V command for formats.
The test is terminated by loss-of-carrier, or an H0, &T0, or Zn command,
and by the timer timing out (S18 time out).
Result Codes
OK - when command execution starts
OK - after sending error count to DTE.
ERROR - if any other self test is active (&T1, &T3, &T6-&T8).
ERROR - if not in Online Command State.
ERROR - if command is issued at other than 1200 or 2400 bits/s.
ERROR - if the RDL acknowledgment signal is not received.
Execution Time
Command execution lasts for the time it takes to receive the RDL acknowledgment
signal, the test time, and time to send error count to DTE.
DTE Interface Lines Affected
DSR
LEDs Affected
MR flashes
Cross Reference
Commands - &Sn, &T0,
&T6, Hn - Control
The Switchhook , Zn - Perform Soft Reset
S-registers - S18
DTE signals - DSR
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