Troubleshooting Terminal, Printer and Serial Device Connections - Edition 4 (32022-90030)

Chapter 2 27

Troubleshooting Procedures

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 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.