HP 3000 Manuals

Troubleshooting Terminal, Printer, and Serial Device Connections

Testing DTC Device Connections 

This section applies if only one device is affected and simple causes
have been ruled out.  In this case, it is appropriate to use TermDSM for
more detailed diagnostics.  This must be done from another terminal or
the console.

TermDSM is part of the Online Diagnostic Subsystem.  The diagnostics in
this section require security level 2 (SM, DI, or OP capability).  For
details on running TermDSM, refer to chapters 3, "Introduction to
TermDSM" and 4, "TermDSM Commands."

TermDSM provides four tests to exercise the DTC device data path.  In
addition, TermDSM provides dump and reset functions for the port serving
that device.

A port dump writes data to a disc file from port buffers.  The dump file
can be analyzed by an HP representative for detailed diagnosis of
software faults.  A port reset terminates the session at that port and
resets the software managers controlling it.


NOTE  Always dump a portbefore resetting it or performing diagnostic
      tests.  The dump file provides a record of the problem which will
      be helpful if the problem occurs again.


Using TermDSM, you can quickly isolate a fault to within the DTC, the
device, or the device cable.  The four DTC-device connection tests are:

 *  Internal Port Loopback Test.  Tests the DTC serial interface card
    (SIC) circuitry for the port that serves the affected device.
    Additional hardware is not required; the affected device can remain
    connected.

 *  External Port Loopback Test.  Checks the same circuitry, plus the
    driver, and the DTC connector for that port.  The device is
    disconnected for this test; a loopback connector is required.  Use
    the loopback connector provided with the DTC for the test.

 *  Terminal Write/Read Test.  Checks the entire DTC device connection.
    This includes the SIC circuitry, the driver, the DTC connector, the
    device cable, and part of the device circuitry.  TermDSM writes a
    line of characters to the device, then reads it back, comparing the
    two.  The affected device remains connected.  This test is useful for 
    only supported terminals and PCs.

 *  Print-to-Port Test.  This test is similar to the Terminal Write/Read
    Test.  However, the character string is transmitted only (not read
    back by TermDSM). The user must check visually that the string
    received at the affected device is the same as was sent.  The test is
    available for all devices.

Your choice of test will depend on:

 *  The type of device you are testing (supported or unsupported;
    terminal or printer).

 *  The availability of the appropriate loopback connector.

The tests can be used individually, or they can be used together to
systematically isolate the fault.  If used together, the following are
recommended test sequences.  For details on these tests, refer to chapter
3, "Introduction to TermDSM" and chapter 4, "TermDSM Commands."

The test sequence to use for supported devices is as follows:

   1.  Internal Port Loopback Test.

        *  If the test fails, the fault is in the DTC (refer to "Testing
           the DTC" later in this chapter).

        *  If the test passes, do the Terminal Write/Read Test.

   2.  Terminal Write/Read Test.

        *  If the test fails, and a loopback connector is available, do
           the External Port Loopback Test.

        *  If the test fails, but no loopback connector is available,
           alternate testing is required (fault might be in the DTC, the
           device, or the device cable).

        *  If the test passes, the fault is in the software.

   3.  External Port Loopback Test.

        *  If the test fails, the fault is in the DTC (refer to "Testing
           the DTC" later in this chapter).

        *  If the test passes, the fault is in the device cable or the
           device.

The test sequence to use for printers or unsupported devices is as
follows:

   1.  Internal Port Loopback Test.

        *  If the test fails, the fault is in the DTC (refer to "Testing
           the DTC" later in this chapter).

        *  If the test passes, but no loopback connector is available,
           alternate testing is required (fault might be in the DTC, the
           device, or the device cable).

        *  If the test passes, and a loopback connector is available, do
           the External Port Loopback Test.

   2.  External Port Loopback Test.

        *  If the test fails, the fault is in the DTC (refer to "Testing
           the DTC" later in this chapter).

        *  If the test passes, do the Print-to-Port Test.

   3.  Print-to-Port Test.

        *  If the test fails, the fault is in the device or the device
           cable.

        *  If the test passes, the fault is in the inbound data path of
           the device or in the device cable.

MPE/iX 5.0 Documentation