Introduction
------------
The "dgnctest" script provides a menu interface for selecting
basic options and subsequently running the main test program:
"/etc/dgnc/utest".

On the following screens, "dgnctest" prompts for input and output
ports, and the type and number of tests to run.  Then "dgnctest"
calls "utest" with the selected options to send a random stream of
data from one port to the other while checking to make sure that
all the data arrive properly.  Status messages are displayed as
the tests are run.

Description of the Tests
------------------------
The "dgnctest" menu interface allows the user to select from
the following test types:

    1. Internal loopback.  This test uses a hardware test mode to to
       internally loop the port's input and output channels so
       tests can be run without any external cables or adapters.
       When selecting this test, "dgnctest" prompts only for a
       single port.

    2. External loopback.  This test uses requires that the port
       under test be fitted with an external loopback plug or
       cable to externally connect the port's input and output
       data and modem control channels.  When selecting this test,
       "dgnctest" prompts only for a single port.

    3. Port-to_port.  This test requires the user to select two ports
       and assumes that they are interconnected with an external
       loopback cable.  A suitable cable will connect the ground
       signals between the two ports, interconnect the transmit line
       on one port to the receive line on the other, jumper Carrier
       Detect and Data Set Ready on one port to Data Terminal Ready
       on the other.  A so-called "Null-modem" cable will generally
       be suitable, though some such cables jumper all the modem
       control lines on each side of the interface effectively
       disabling hardware flow control (since there is no way for
       one port to communicate these signals to the other).

Interrupting Tests
------------------
Tests in progress can be halted by pressing any key.

Expert Mode
-----------
The "dgnctest" menu interface provides access to only the most
common options of the main test program, "utest".  Additional utest
options can be run in "expert mode" from the command line.
To access "expert mode", select "Exit" at the main menu.
To see all the "utest" options, type:

       /etc/dgnc/utest -h | more
