14-4 CHAPTER 14: TESTING THE CONNECTION
If you use the S18 test timer, but in the process of testing you issu e an
ATZ command, S18 resets to zero and the timer is disabled. You cannot
store a value for S18 in NVRAM; its power-on and reset default is always
zero.
Using AT&T8
This analog loopback option causes the Business Modem to send an
internal test pattern to its transmitter and loop it back to the receiver. An
internal error detector counts any errors and, when the test is ended,
sends the number of errors or 000 (no errors) to the screen.
Since you don't type anything during this test, and the Business Modem
does not send anything to the screen, this option verifies only the
Business Modem. If there are no errors but your problem continues, it
may be at the computer interface.
1Send AT&M0&N3S14.0=0 to the modem prepare for testing.
This command disables error control, fixes the connection rate at 2400
bps, and makes the Business Modem return to command mode when
you type +++.
2Send AT&T8 to begin the test.
The Business Modem enters analog loopback (AL) mode, and sends a
CONNECT message. The MR status light flashes. The V.Everyhing then
sends its internal test pattern to the transmitter, and loops the pattern
back to the receiver. You will not see any data on your screen.
3Send the escape code, +++, and then AT&T0 to end the test.
Alternatively, you can end the test by sending ATH or ATZ. Be careful,
because ATZ resets the modem in addition to ending the test.
In any case, the Business Modem hangs up and returns a three-digit
code, followed by OK.
4Send AT&M4, unless you used a reset command (ATZ or ATZ!).
The code Indicates
000 No errors were found
255 255 or more errors
An ERROR message indicates that you issued an invalid command.