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When you select option 11 from the DEVICE LIST, you see these
prompts:
Attach loop-back connector to serial port.
Enter Y to start this check when connector is
attached, or
Enter N to return to the menu.
Insert the loop-back connector. Then press Y and
check.
First, the computer checks the serial port control lines to see that they
are able to change from high to low and vice versa. No messages
display during this part of the test unless an error occurs.
The second test is an echo back check during which the port sends
data to itself in a fixed data format, at all the possible baud rates.
When this test begins, you see these messages:
RS232C echo back check - at various baud rates
Current baud rate is 75
Current test data is 00
Each baud rate is tested in turn, and the display informs you of the
progress of the test. If the port does not become ready correctly, a
timeout error occurs. If any data received does not match the data
sent, a verify error occurs, and the computer reports the transmitted
and received data at the time of the error.
The final test is an echo back check during which the port sends data
to itself at 9600 baud, using various data formats. At the start of the
test, you see these messages:
RS232C echo back check-with various data formats
Current data format: 5 data bits, 1 stop bits,
Current test data is 00
Once again, if any data received does not match the data sent, a
verify error occurs, and the computer reports the transmitted and
received data at the time of the error.
C-24
Performing System Diagnostics
parity - NONE
to start the
Enter
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