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Configuring Modem in SCO UnixWare


Use this procedure to configure a RealPort device for a Dial-in/Dial-out modem connection. Configuring a device for a modem requires familiarity with both the operating system and the modem being used. While the following procedure is sufficient for most cases, it may be necessary to take additional steps to properly configure your modem or to set up the operating system for a specific application.

The Digi device should be properly installed, configured and functioning before proceeding.


  1. Connect a proper cable between the port and modem.
  2. Disable both the modem and non-modem control ports. This can be done through sysadm. SCO UnixWare users can enable and disable ports through scoadmin>Hardware>Serial Manager.
  3. Modify the file /usr/lib/uucp/Devices. Create an entry look like this:

    Direct term/a01m,M - 38400 direct_modem

    The device ttya01m used here is just an example.

    Comment out any ACU lines relating to this device until dial-in is working properly.

    An ACU line is necessary for correct operation of the modem in dial-out applications. Refer to the modem manual or to the modem manufacturer for the correct modem initialization string to use for your modem. Refer to the SCO UnixWare Administration handbook for guidance on setting up an appropriate ACU entry that uses this initialization string.

  4. Connect to the modem by entering this command at a Unix root prompt:

    cu -l /dev/term/a01m -s 38400

    It may be necessary to use a01s instead:

    cu -l /dev/term/a01s -s 38400

  5. Train the modem to the port speed with this at command:


  6. Depending on the modem, it may be necessary to enable auto-answer with this at command:


  7. Disconnect from the modem by entering tilde-period.


  8. Enable and configure the port using one of the these three methods:



    Using pmadm

    This method can be used in any SVR4-based Unix system.  Though effective, it is often tedious to use because the command used is complicated. See Configuring a Device with pmadm.

    Using the Serial Manager
    in SCO UnixWare

    This method works only in SCO UnixWare. See General SCO UnixWare Device Configuration.

    Using sysadm

    This procedure works only in SVR4 systems that have access to a utility called sysadm. See General SVR4 Device Configuration.

Last updated: Jan 11, 2024

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