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T
ROUBLESHOOTING AND
O
NLINE
H
ELP
R
ESOURCES
80
PROBLEM
DIAGNOSIS
POSSIBLE SOLUTION
Your communications
software is reporting many
cyclic redundancy check
(CRC) errors and low
characters per second
(CPS).
You may have a bad phone
line.
Optimum flow control settings
may not be enabled on your
modem.
The serial port rate in your
communications software may
be set too high for your
modem’s UART or your
area’s phone lines.
The remote site you are dialing
into may have trouble with the
file transfer protocol.
There may be a Terminate and
Stay Resident (TSR) program
(such as a screen saver or
virus scanner) running in the
background, disrupting data
communications.
Try placing the call again. The phone company routes calls differently each time.
In terminal mode, type AT&F1 and press ENTER to load the optimum hardware flow
control settings.
Lower the serial port rate in your communications software to 57,600 bps, 38,400
bps, or 19,200 bps. Some software programs (including AOL) allow port settings of
14,400, 28,800, and 33,600. These settings are invalid and should not be used.
NOTE: The port rate for an 56K modem cannot be set lower than 57,600 if you want
to achieve a high-speed connection.
Try using a different file transfer protocol. Do not use Xmodem if other protocols are
available. Zmodem is the preferred protocol.
Disable any Terminate and Stay Resident (TSR) programs running in the
background. If you have software running as a TSR, check the software’s manual for
information about disabling its ability to operate as a TSR.