Loopback Tests; Testing The Auxiliary Console Port (Exer); Testing The Ethernet Ports (Netexer) - DEC 4000 AXP Service Manual

3.1.12 Loopback Tests

Internal and external loopback tests can be used to isolate a failure by testing
segments of a particular control or data path. The loopback tests are a subset of
the RBDs.

3.1.12.1 Testing the Auxiliary Console Port (exer)

Using a loopback connector (29–24795–00) and a form of the
can test the auxiliary serial port. Before running the loopback test, you must
set the tt_allow_login environment variable to 1; after the test is completed, you
must set tt_allow_login to 0.
Use the following commands to send a fixed data pattern through the auxiliary
serial port:
>>> set tt_allow_login 1
>>> exer -bs 1 -a "wRc" -p 0 tta1 &
>>> kill_diags
>>> set tt_allow_login 0
>>>
In the above command, the portion in quotes (the write, read, and compare
instruction) is case sensitive. The background operator &, at the end of the
command, causes the loopback tests to run in the background. Nothing is
displayed unless an error occurs.
To terminate the console loopback test, use the
individual diagnostic or the
Use the show_status display to determine the process ID when killing an
individual diagnostic test.

3.1.12.2 Testing the Ethernet Ports (netexer)

The command performs an Ethernet port-to-port MOP loopback test
netexer
between eza0 and ezb0. The network ports must be connected and terminated.
The loopback tests are run in the background. Nothing is displayed unless an
error occurs.
To terminate the console loopback test, use the
individual diagnostic or the
Use the show_status display to determine the process ID when killing an
individual diagnostic test.
3–20 Running System Diagnostics
kill
command to terminate all diagnostics.
kill_diags
kill
command to terminate all diagnostics.
kill_diags
exer command, you
command to terminate the
command to terminate the