OKIDATA Microline 395 Service Handbook page 134

%4.8.03 Serial Interface - Loopback Test
4.8.03 Serial Interface - Loopback Test
NOTE:
In order to run this test, a serial loopback test connector must be attached to the printers serial port.
Procedure
1. Place the printer in the Serial Diagnostic Mode
Set the DIAGNOSTIC TEST menu item to YES.
2. Turn the printer power OFF.
3. Attach the loopback test connector to the printers serial port.
4. Install continuous feed paper.
5. Power ON the printer.
6. The message LOOP TEST will be printed.
7. The size of the Message Buffer will be printed.
8. One of the following messages will be printed next.
If the message OK is printed, the serial interface function has been tested and no problems were found.
If the message IF BAD is printed, the signal logic was tested and a problem was found.
9. Hexadecimal characters 20 through 7F are transmitted through the transmit data line.
10. The receive data line receives the characters.
11. The message buffer then stores the characters.
12. The data is then printed.
13. The test will run until the SELECT switch is pressed or the printer is powered OFF.
Serial Loopback Plug Diagram
ML395 ( 96-02-03 )