ADTRAN XRT - Manual (Page 42)

Chapter 3. Installing an Analog Modem
30 Express XR/XRT Quick Start Guide 61200.153L1-13
13. Click Close.
14. The external analog modem may now be used, or you may
restart the Express Configuration Wizard and deselect the
Connect External Modem
option to enable the Express XRT.
Configuring an External Analog Modem
If the modem does not support 230.4 kbps, Switch 1 on the back
panel of the Express XRT must be On (down) to install and use
an external modem with the Express XRT. This limits the DTE
speed to 115.2 kbps when using the Express XRT with an exter-
nal modem. To re-enable the 230.4 kbps operation for ISDN
connections, set Switch 1 to the On position.
When using applications supporting Express XRT operation at
230.4 kbps with an external analog modem that does not support
230.4 kbps, attach the Express XRT to the high speed 16650
UART COM port and connect the external modem to a separate
COM port. This allows the Express XRT to operate at 230.4kbps
and the external modem to operate at the reduced speed.
Required External Analog Modem Settings
There is one setting in the external modem that is required
before trying to enable the modem with the Express Configura-
tion Wizard. The Carrier Detect signal from the modem should
be set to Normal (track the CD signal). This can be accom-
plished by using the AT command AT&C1. AT commands can
be entered into the modem using the following procedure:
indicates to press the Enter key on the keyboard.
1. Open a terminal emulation session using HyperACCESS or
HyperTerminal.
2. Type AT_L1
3. Type AT
4. Type ATI
5. Type AT &C1
6. Type AT&W
7. Type AT_L0