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3.16 Diagnostic Commands
The MT2834MR6 has two diagnostic commands and four diagnostic modes. The power-on self-test is
activated every time power is applied. The U command selects a loopback test, while the &T command
enables a modem to respond to a loopback test from another modem. See Chapter 6, "Testing the
MT2834MR6," for a fuller discussion. Refer to the L8 command to see how to list the diagnostic online status.
&Tn
Respond to Remote Digital Loopback Signal
n = 4 or 5
Default: &T5
The MT2834MR6 has several self-test features, discussed in Chapter 6. The &T command
enables or disables the modem's ability to recognize the remote digital loopback (RDL) test
signal. (See Chapter 6 for remote digital loopback test procedures.)
AT&T4 lets the modem respond to an RDL signal, and places it in digital loopback.
AT&T5 causes the modem to ignore the RDL signal.
Un
Loopback Test Modes
n = 0–3
Default: None
Loopback tests send data through the modem in such a way that it loops back to the
terminal where it was entered, testing all the circuits along the way. The U command selects
from several loopback tests. See Chapter 6, "Testing Your Modem," for more information.
ATU0 places the modem in originate mode for the local analog loopback test.
ATU1 places the modem in answer mode for the local analog loopback test.
ATU2 performs the remote digital loopback test.
ATU3 performs the local digital loopback test.
Chapter 3 - AT Commands
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