Epson 20020 Manuel D’Utilisation

Use this option to test the functions of the primary serial

communications (RS-232C) port. To perform the test, you

must insert a special loop-back connector into the RS-232C

port so that the computer can check the individual pins of the

port. Contact your Customer Care Center if you need a loop-

back connector (or see Appendix A for the signal/pin

assignments if you want to make your own loop-back

connector). Note that a different connector is required to test

the parallel port.

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 

Enter 

to

start the 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 are displayed 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 progress is displayed.
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.

Performing System Diagnostics