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HOW TO: Configura a Modem Using RealPort in AIX


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 and RealPort should be properly installed, configured and functioning before proceeding. This procedure assumes that a tty has been created for the modem. See Creating and Configuringttys.


  1. Turn the modem on.

  2. Access a root prompt on the AIX system.

  3. Add an entry for the device in the file /usr/lib/uucp/Devices. The following example allows a connection of 9600 baud to the device:

    Direct tty3 - 9600 direct

  4. Use the following command to connect to the modem:

    cu -ml ttyX

    In this command, ttyX is the device name for the port.

    The modem should respond with an AT prompt.

  5. Train the modem to the port speed by entering this command at the AT prompt: 


  1. Terminate the connection by entering: 

     ~.           (a tilde followed by a period)

  1. At an AIX root prompt, enter this command:

    smit tty

  2. Choose Change/Show Characteristics of a TTY.

  3. Choose a TTY device. This is an example of a listed device:

    tty7 Available 00-00-04-02 Asynchronous Terminal

    In this example, the first 00 is the bus number. This is unused and will always be 00. The second 00 is the slot number. This is unused and will always be 00. The number 04 is the sa device number. The number 02 is the port number.

  4. Set Enable LOGIN to share.

  5. Set BAUD rate to the modem''''s highest configurable baud rate.

  6. Set PARITY, BITS per character, and number of STOP BITS to match the settings of the modem.

  7. Set FLOW CONTROL to be used to match the flow control used by the modem.

Last updated: Jun 21, 2019

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