You are viewing an article about an obsolete product. Information on this page is provided as-is and not supported.

HOW TO: Configure Acceleport serial ports for Dial-In Modem connections to SCO Openserver


Modem Configuration requires familiarity with both the specific OS 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 OS for Dial-In operation or for use with a specific application.


1) Using a Serial Cable pinned for use with a Modem

Use a Modem Cable as found under the cable selector for your product on the Digi Support page.

2) Configuring the Unix Server

  1. In /etc/inittab, set the upper-case tty device to gettydefs entry o
    [o = 38400 speed, which should work for any 9600 baud or faster modem]
  2. Disable both the upper and lower case devices
  3. In /usr/lib/uucp/Devices, make a Direct entry, similar to this:
            Direct ttya01 - 38400 direct [lower case device name]
  4. Comment out any ACU entries within the file relating to this device until dialin is working properly.

    Note: Some applications may require an ACU entry in the Devices file. If your application requires such an entry, refer to your modem manual or to the modem manufacturer for the correct modem initialization string to use for your modem, and to the SCO Administration handbook for guidance on setting up an appropriate ACU entry which uses the initialization string.
  5. Connect to the modem:
    • cu -l /dev/ttya01 -s 38400
    • ats0=1 [answer after first ring]
    • at&w [train modem to port speed]
    • [send any other AT commands specific to your particular modem]
    • ~. [tilde period, to end cu]
  6. finish configuring the port:
    • ditty rtspace ctspace -ixon -ixoff -ixany /dev/ttya01 [to set hardware flow control]
    • ditty altpin /dev/ttya01 [if using 8 wire cable]

      (These lines can be run from command prompt so they take effect immediately, but also need to be added to /etc/rc.d/8/userdef to automatically execute at boot time)

      Note: Altpin switches the pin assignment of DSR and DCD. When used with 8 wire RJ-45 cables, this makes DCD accesible on 8 wire pin 1. ditty -altpin would be the command to disable this flag.

The port is now configured for Dial-Out use.

To add Dial-In capability:

enable ttyA01

The port is now configured for Dial-In.

Possible error messages:

  • NO DEVICES AVAILABLE -- check Devices file
  • SYSTEM not in Systems FILE -- check Devices file
  • DEVICE LOCKED -- there is a lock file in /usr/spool/uucp/LCK..##
  • CAN'T ACCESS DEVICE -- check owner and permissions of /dev/ttya01
    this can be caused by the lack of an ACU entry in the Devices file
  • DIALER [whatever] -- the ACU entry is incorrect, refer to the modem and system operators manuals

*In SCO Unix, the upper case devices are used for Dial-In, while lower case devices are for Dial-Out and modem configuration:

Device Dialin Dialout/Printer/Terminal
xem, c/x, epc/x
and portserver
ttyA01 ttya01
xe and xi ttyi1A ttyi1a
xr ttyr1A ttyr1a
Last updated: Jun 11, 2019

Recently Viewed

No recently viewed articles

Did you find this article helpful?