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7.0 Diagnostics
In Hayes emulation mode only, initiate the ALB test using the command &T1
(preceded by AT). In any mode, initiate the ALB test using the modem’s
front panel controls, explained in the following paragraphs.
Make sure the modem is idle, the data rate is the same as the DTE’s data rate,
and the DTR circuit is on. (If TR is present on the EIA status screen, the DTR
circuit is on.)
From the second page of the LCD MAIN MENU, select TEST. TEST takes you
to screen 1 of the LOCAL TEST menu, where ALB is displayed as one of the
test selections. Select ALB.
The ANALOG LOOPBACK screen is displayed, with ON and OFF as the
possible selections.
Select ON to activate the test. In general, the "DSR during ALB test option"
discussed in Chapter 3 should be left ON (default selection) to avoid
disrupting the DTE and DTE software operations.
The EIA status screen is displayed while the test is being conducted. Make
sure that test data is being generated. Watch for data errors. By transmitting
test data and comparing it with the received copy, you can make sure the DTE
and modem are both working.
To end the test, press the ENT pushbutton to return to the ANALOG
LOOPBACK screen, and then select OFF.
7.7.2 A
NALOG
L
OOPBACK
S
ELF
-T
EST
(ALBST)
In the analog loopback self test, the modem is placed in analog loopback and
data is sent and received by an internal 511-bit pattern generator and
receiver. Therefore, no DTE or external BERT is necessary. Figure 7-2 shows
the data flow for this test.
In Hayes mode only, initiate the ALBST using the command &T8 (preceded
by AT). In any mode, initiate the ALBST using the modem’s front-panel
controls, as follows:
From page 2 of the LCD MAIN MENU, select TEST. This takes you to screen
1 of the LOCAL TEST menu, where ALBST is visible as one of the selections.
Select ALBST.