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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 Chapter 3 “Introduction to TermDSM” and Chapter 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 disk 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 port before 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 (for DTC 16s and DTC
48s only). 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: 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.
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.
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: 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.
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.
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.
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