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USRobotics V.34 User Manual

Page 181

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COURIER HIGH SPEED MODEMS

F-16 Dedicated and Leased Line Operations

Set the modem as follows:

1. Set your terminal or communications software to the rate at

which you want the modems to communicate. For
example, use a terminal/software setting of 19.2K bps and,
if both modems have the capability, they will connect at
14.4K bps. The following instructions assume that you are
familiar with the guidelines on using the &B and &H
commands (Chapter 3) and the &W command (Chapter 3).

2. Send the modem the following command:

AT &B1 &S2 &H1 &L1 &W

&B1 fixes the modem's computer interface rate at the same
serial port rate you selected when setting up your
communications software. &S2 causes the modem to send a
Clear to Send (CTS) signal

only after it sends the Carrier

Detect (CD) signal, that is, only after it connects with the
remote modem. (See the note that follows.) &H1 enables
hardware (CTS) flow control.

&L1 forces the modems off hook at power on and enables
them to re-establish the connection should it be broken.
&W writes the settings to nonvolatile memory (NVRAM) as
power-on defaults.
NOTE: We recommend using the &S2 setting to delay CTS
until after the connection is made, as a precaution. If the
modems are in the process of connecting or reconnecting,
the Courier interprets any keyboard data entry, including
an accidental key stroke, as a

key-press abort, and hangs up.

Delaying CTS until after carrier detection prevents this from
happening, for example, if you are typing data to the remote
modem when the modems momentarily disconnect and
begin to reconnect. However, you have to set the modem
for hardware flow control, &H1.

If your software or machine does not support Clear to Send
(CTS), don't include &S2 and &H1 in the command string as
suggested above. Follow the Transmit Data flow control
(&H) guidelines in Chapter 3. But keep in mind that if the
modems fail to connect or reconnect, the reason could be a
key-press abort.