33
the command ATi10, and look for Enhanced Carrier Modulation Control.
H
ARDWARE
F
LOW
C
ONTROL
Hardware Handshaking Cable for Flow Control on External
Modems
To communicate at high speeds using external modems, it is CRITICAL that you use a cable with
“RTS/CTS Hardware Handshaking” (such as the one supplied with your modem). With error
correction and data compression, the modem can send data to the computer faster than the
computer can accept it. When this happens, the computer tells the modem to slow down. Similarly,
if data is not sent correctly to the modem and needs to be resent, the modem needs to be able to tell
the computer to wait. This is called “flow control” or “handshaking” and helps to prevent data
from being lost.
How to Get a Hardware Handshaking Cable
If your modem didn’t come with a cable or you’ve lost your cable, your local dealer should be able
to provide you with one that supports hardware handshaking. When you ask for a new cable, be
careful to specify that it needs to support hardware handshaking. If your modem came with a cable,
it supports hardware handshaking.
Using Hardware or Software Flow Control
Enable hardware (RTS/CTS) flow control rather than software (XON/XOFF) flow control because
the results are generally faster and more reliable.
To enable hardware flow control:
1
Use a hardware handshaking cable.
2
Use your software to turn ON hardware (RTS/CTS) flow control. This should automatically
turn OFF software (XON/XOFF) flow control, but you may need to use your software to
manually turn off software (XON/XOFF) flow control.
3
Issue the
&K3
command to turn ON hardware flow control in the modem.(This is the default;
both
&FØ
and
&F1
include
&K3
.)
4
Issue the
&W
command to save the setting.
