COURIER HIGH SPEED MODEMS
NOTE: Earlier U.S. Robotics modems require bit 3 to be enabled in order to grant RDL to a remote modem. The modem now requires its default &T4 setting instead. To perform RDL with a U.S. Robotics modem that does not use the &T test repertoire, that modem should be set to S16=8 before it can grant RDL testing.
ANALOG LOOPBACK (AL)⎯S16=1D
As with the &T AL test, do not attempt this test under error control. HST and Dual Standard modems should be tested at 2400 bps or lower, to avoid asymmetrical modulation at higher speeds.
To use the modem's Test Pattern (S16, bit 2) instead of typing your own data, see Test Pattern−S16=4 later in this appendix.
1.To initiate testing, type AT&M0S16=1D. The modem disables error control, enters AL mode and sends a CONNECT result code. The MR status light flashes.
2.Type data to the modem for the modem to transmit, loop to its receiver, and output to the screen. An alternative is to use the Test Pattern, described later.
3.End the test by not typing anything for one second, then typing three pluses (+++), and waiting another second. This forces the modem back to Command mode. If DIP switch 9 is OFF, the modem exits AL mode and returns to Command mode. If DIP switch 9 is ON, the modem maintains the con- nection when it receives the +++ escape code. Issue the ATH command to end AL mode.
4.Reset the modem to Data mode, S16=0, and error control (&M4), or issue the ATZ (reset) command.
DIAL TEST⎯S16=2
The Dial Test is used for factory testing the frequencies of tone values. When
Modem Testing
