HP EISA/PCI Multiplexer Family Cabling, Diagnostics and Troubleshooting Manual

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Troubleshooting and Diagnostics
Driver Status Menu Selections
Loopback
Highlight Loopback and press Return key (see Figure 6-14).
Figure 6-14 Diagnostics loopback test
The loopback test is designed to test the primary components of the
adapter cards and their functionality. The test can be run on a single
port or a group of ports at the same time. The test does not require that
the selected port(s) have the transmit and receive pins wired together.
You have the option of running the test using an internal feature which
loops back the data sent out. This simulates a loopback cable. Data is
looped both toward the computer as well as toward the terminal.
The program starts by writing a data pattern to the selected port(s) and
reading the data back and comparing it to a pattern written out. The
program reports, at regular intervals, the number of characters
transmitted and received, errors and calculated receive rates. The data
transmitted is an ascending pattern that starts at 1 decimal to 256
decimal. We highly recommend that you disconnect any devices
connected to ports being tested (in external loopback mode). Attach a
loop back connector that ties the port’s transmit and receive signals
together. Because control characters are being sent, any terminals or
printers that are connected to the selected ports during the external
loopback test may hang. To exit this menu level, press the Esc key twice.