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

28 Chapter 2
Troubleshooting Procedures
Testing DTC Device Connections
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.