Configuring your system and modem to work together

If you are using switched carrier, ensure that the tty port's jumpers are not set to carrier detect (``CD'') always high.

If the modem is configured for 9600bps or faster, configure the modem for hardware flow control. Also, if the modem is configured for hardware flow control, specify a hardware flow controlled port. This is a port referenced as ``term/00h''; for example, in /etc/uucp/Devices.

Use the following guidelines to configure your modem and system for bi-directional use (that is, for both dialing in and dialing out):

1. Be sure you have reliable dial-out capability before you do any of the following:

   • Enable the system to answer calls.

   • Enable the modem to answer calls.

   • Enable error correction logic (if available on your modem).

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     NOTE: It is best to have dial-out capability working properly before calls are received.

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2. Be sure to run ttyadm with the -b flag set so that ttymon is properly configured for the bi-directional line.

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   NOTE: These steps ensure that the proper locks and communications signals will be honored when the line is in use.

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3. Set the default configuration parameters to specify local echo off. This will avoid runaway echo when waiting for a call.

4. Enable bi-directional use by doing the following:

   • Set the value of the S0 register to be greater than 0. This will enable auto-answer mode.

   • Activate the ttymon daemon.

5. If the label for the modem in /etc/uucp/Devices is ``hayes'', set the parameters ``&C1'' and ``&D2''.

6. After configuration, add the port as an ACU line in /etc/uucp/Devices (see Devices(4bnu)). For example:

   ACU term/00 - Any hayes
   

7. The modem may be configured to ignore DTR (Data Terminal Ready). If this is done, be sure that the phone line disconnects after use. You may disconnect at command level by using stty(1). For example, the command stty 0 sets the baud rate to 0, which causes a disconnect. You can also issue AT commands directly to the modem. For example, the command ATH0 causes a hang-up.