USRobotics V.34 - Manual (Page 160)

COURIER HIGH SPEED MODEMS
Troubleshooting E-1
APPENDIX E. TROUBLESHOOTING
You may occasionally encounter one of the problems listed here.
They are divided into three categories: Running the SDL.EXE
Upgrade Program, Before Establishing the Link, and During
Data Transfer.
Running the SDL.EXE Upgrade Program
Your modem . . .
Is indicating an error
Try running the SDL program at a lower serial port rate. If your
computer doesn’t have a 16550 UART, a slower serial port rate
can make all the difference.
You can also try running the program on a different PC. An
idiosyncracy of an off-brand PC or an uncommon version of
DOS may lock up the SDL program.
Before Establishing the Link
Your modem . . .
Doesn't answer the phone or go off hook to dial a number
Review your communications software manual to see what
Data Terminal Ready (DTR) operations your software requires.
Then check to see if DIP switch 1 is set correctly. Also, check to
make sure your terminal or computer is sending a DTR signal
via the RS-232 interface.
Doesn't respond OK when you type AT <Enter>
1. Make sure you're typing in either upper case or lower case
letters, not a combination, and that you press the Enter key.
2. If you're using a computer, make sure it is in Terminal
mode. This is a communications software function. See
Testing the Modem in Chapter 2.