COURIER HIGH SPEED MODEMS
Modem Testing H-1
APPENDIX H. MODEM TESTING
Testing is available with the &T command or Register S16. All
loopback testing conforms to ITU-T Recommendation V.54.
Earlier U.S. Robotics high speed modems, however, did not
perform the &T test repertoire.
Only one test can be performed at a given time. If you send a
test command while the modem is in test mode, you'll receive
an ERROR message.
NOTE: Testing is not available when the modem is in
synchronous mode: &M1, &M6, &M7.
TESTING WITH &T
The tests supported through the &T command include analog
loopback, digital loopback and remote digital loopback. Users
can key in their own data during testing, or use the modem's
internal test pattern and error detector.
In all cases, disable error control before testing. If the modem is
detecting errors and retransmitting the affected data, your
results will be invalid.
During testing, the MR status light flashes.
Ending a Test
&T0, S18
Issuing the &T0 command terminates a test. Alternatively, set
Register S18 to a specified number of seconds, for example,
S18=10. When the 10 seconds are up, the modem automatically
ends the test and returns to Command mode. If the test was
Analog Loopback, the &T0 command hangs up the modem. If
the test was Digital or Remote Digital Loopback, issue an ATH
command to hang up the modem, or an ATZ command to hang
up the modem and reset it to its defaults.
NOTE: If you use the S18 test timer, but in the process of
testing you issue an ATZ command, S18 resets to zero and the
timer is disabled. You cannot store a value for S18 in
nonvolatile memory; its power-on and reset default is always
zero.