Category : Tutorials + Patches
Archive   : USRMANUL.ZIP
Filename : APD.ASC
APPENDIX D. PROBLEMS AND SOLUTIONS
You may occasionally encounter one of
the problems listed here. They are
divided into two categories: before and
during the exchange of user information
over the data link.
Before Establishment of the Data Link
Your modem . . .
Doesn't answer the phone or go off hook to
dial a number
Review the Settings Supplement that came
with the modem or 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
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.
3. Check to see that your terminal or
software is set to the correct bit
Problems and Solutions D-1
COURIER HIGH SPEED MODEMS
rate and word length (7 bits with or
without a parity bit, or 8 bits and
no parity). If you're using a
computer, make sure your software is
set to the correct communications
port.
4. Check that DIP switch 8 is DOWN, for
command set recognition. If the
switch is UP, power off the modem,
set the switch DOWN, and power on the
modem again. Try typing AT
again.
5. Check that DIP switch 3 is DOWN, for
result code display, and that DIP
switch 2 is UP, for verbal result
codes. If not, change the switch(es)
and type ATZ
whichever of these commands is
needed:
D-2 Problems and Solutions
COURIER HIGH SPEED MODEMS
ATQ0
ATV1
message)
6. Review the Settings Supplement that
came with the modem or your communi-
cations software manual to see what
Carrier Detect (CD) operations your
software requires. Then check to see
if DIP switch 6 is set correctly.
7. A rare condition is that your
terminal or computer reverses the
send/receive functions at the RS-232
interface. See Appendix B-1,
Appendix B-3, Quad switch, and your
equipment documentation.
Displays double characters
Both your modem's and software's local
echo are characters on. You can turn
your software's local echo off. Or turn
the modem's echo off by either resetting
DIP switch 4 and sending the modem the
ATZ command, or by sending the modem the
ATE0 command.
Your computer . . .
Reacts as though a data link has been
established, but no call has been received
DIP switch 6 is set DOWN at the factory
for Carrier Detect (CD) override, but
your system may require that the
override be turned OFF.
Review your terminal's manual, the
Settings Supplement that came with the
modem or your communications software
manual to see what CD operations are
Problems and Solutions D-3
COURIER HIGH SPEED MODEMS
required. Then check to see if DIP
switch 6 is set correctly.
When the modem is in Answer mode, acts if a
Carriage Return has been entered, but
nothing has been typed at the keyboard
Your software may be misreading signals
from the modem as it automatically sends
a Carriage Return and a Line Feed before
and after the RING and CONNECT messages.
Sending the Quiet Mode command, ATQ1
D-4 Problems and Solutions
COURIER HIGH SPEED MODEMS
Both modems . . .
Exchange carrier signals, but fail to
establish a communications link
1. Asynchronous operations: Check to
make sure the proper bit rate, word
length, parity and number of Stop
bits have been selected. Synchronous
operations: review the link
instructions in Chapter 7. If you've
set the modem to the correct
configuration, the problem may be
with the synchronous adapter or with
the system you're trying to call.
2. Check to see that your modem is at
the correct Bn setting to connect
with either an HST modem (B1 setting)
or V.32 modem (B0 setting). Type
ATI4 for a display of the Courier's
current settings and, if necessary,
send the modem the correct setting.
3. If your modem is attempting to answer
a V.32 call, you may need to lengthen
the extra V.32 answer tones. See S28
in Appendix B-5.
4. Make sure the modem at the other end
of the line is USR-HST compatible at
14.4K or 9600 bps, V.32-compatible at
9600 bps, V.22 bis-compatible at 2400
bps, Bell 212A-compatible at 1200
bps, or Bell 103-compatible at 300
bps. These are the common signaling
standards for full duplex dial-up
network transmission in the U.S.
5. If none of the above corrects the
problem, it's likely that the quality
of the phone connection is poor and
that the other modem is missing the
Problems and Solutions D-5
COURIER HIGH SPEED MODEMS
signals your modem is transmitting.
The variable quality of phone line
connections may be due to any number
of conditions in the phone service's
equipment or the current environment.
Try several calls, and if you still
can't get through, try calling
another modem. If the second modem
accepts your call, the problem may
lie with the modem you first tried to
call.
During Data Transfer
Your screen displays . . .
Only brackets
Check to make sure that both modems are
set to the same bit rate, word length,
parity and number of Stop bits. If the
settings
D-6 Problems and Solutions
COURIER HIGH SPEED MODEMS
are correct, the problem may be with the
phone line. Try the following measures:
1. Try placing the call again. The
phone company routes even local calls
differently each time you call.
2. Try calling a different modem to see
if the problem persists. The problem
may be with the modem you first tried
to call.
Random or garbage characters
Check to make sure that both modems are
set to the same bit rate, word length,
parity, and number of Stop bits.
If the modem is set to a fixed DTE rate
(&B1) and your software is fixed at
19.2K or 38.4K bps, the reason may be
one of the following:
1. Your computer may not support the
high rate. If this is the case, fix
your software rate at 9600 bps and
disable high-speed V.32 bis
modulation: ATS34=3 or ATS34 .0=1
.1=1.
2. If you use memory-resident programs
(TSRs), they may be interfering. Try
disabling them before you run your
communications software. The same is
true of disk-caching programs.
3. Check to see that your software and
the modem are set for the same kind
of flow control, either hardware or
software. Some communications
programs also require that you dis-
able the kind you are not using.
Problems and Solutions D-7
COURIER HIGH SPEED MODEMS
Double characters
Your modem's online local echo is on and
the remote modem is also echoing. The
only way to correct this is to bring the
modem back to Command mode (wait one
second without transmitting data, type
+++, wait another second). Then type
the command to turn off your online echo
(ATF1
If DIP switch 9 is UP (factory setting),
the modem hangs up when it returns to
Command mode, and you'll have to call
again. If DIP switch 9 is DOWN, the
modem maintains its connection. You can
return it back online by typing ATO
D-8 Problems and Solutions
COURIER HIGH SPEED MODEMS
IF YOU STILL HAVE PROBLEMS
The problems described above are by far
the most common ones that users
encounter. If the suggestions we've
given don't clear up your difficulties,
try the following:
1. Review the manual carefully to see if
you've missed something.
2. Call or visit your dealer. Chances
are your dealer will be able to give
you the assistance you need. This is
much more efficient and time-saving
than returning the modem to
USRobotics.
3. If your dealer can't clear up your
difficulties, call the USRobotics
Technical Support Department at
800/982-5151. Our Service
Representatives will be happy to give
you assistance over the phone Monday
through Friday from 8:30 a.m. to 5
p.m. (Central Time Zone).
4. If necessary, the Service
Representative you talk to may give
you a Return Materials Authorization
(RMA) number. Modems without an RMA
number will not be accepted.
5. If you do return the modem to us,
please use the following procedures.
a. Ship the unit, postage paid, in
its original container. If the
original container is not
available, pack the modem carefully
in a strong box of corrugated
Problems and Solutions D-9
COURIER HIGH SPEED MODEMS
cardboard with plenty of packing
material.
b. Be sure to include your RMA
number inside the package, along
with your name and address. Put
your return address and your RMA
number on the shipping label as
well.
c. Ship the well-packed modem to
the following address.
Technical Support Department
U.S. Robotics, Inc.
8100 North McCormick Boulevard
Skokie, Illinois 60076
d. Please note that USRobotics
will not accept packages sent COD,
so be sure to send the modem
postage paid.
e. USRobotics will repair your
modem and return it to you via
United Parcel Service.
D-10 Problems and Solutions
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