0049-2702-XXX Alliance Series Modems – USER MANUAL
08/05/2010
Rev. A
Page 145 of 197
Select ON to activate the test. (In general, the DSR during ALB test option discussed in Chapter
2 should be left ON – the default selection – to avoid disrupting the DTE and DTE software
operations.)
The TIA/EIA status screen will be displayed while the test is being conducted. Ensure that test
data is being generated. Watch for data errors. By transmitting test data and comparing it with
received copy, the DTE and modem are checked for proper operation.
To end the test, press the ENT pushbutton to return to the ANALOG LOOPBACK screen, and
then select OFF.
Pin 18 Control
The ALB test can also be activated by positive voltage on TIA/EIA pin 18 if the ALB-DTE
Ctrl’ed option is enabled.
Analog Loopback Self Test (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 6-2 shows the data flow for this test.
Figure 6-2. Analog loopback self test (ALBST)
Hayes Mode (&T8)
Initiate the analog loopback self test by entering the command
AT &T8
.
When the test is complete, the ALX will send a three-digit error code to the terminal (in Hayes
mode only). If there are no errors, the error code will be 000. If there are errors, the code will
range from 001 (1 error) to 255. (The error code will not exceed 255, even if there are more than
255 errors.)
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Страница 189: ...0049 2702 XXX Alliance Series Modems USER MANUAL 08 05 2010 Rev A Page 185 of 197 Figure D 1 Connector pin assignments ...