Lexmark X644E Technical Reference Manual page 329

Using an IBM-Compatible Personal Computer with Serial Interface RS-232C
Note:
If you are using any of the above products, or if your computer has a 9-pin D shell
connector that conforms to the IBM designed 9-pin serial port, use a 9-pin to 25-pin
cable, such as IBM Part Number 6450242 (254 mm or 10 in.).
Null modem cables, such as Lexmark part number 1038693 [15.24 m (50 ft)], will
connect the converter cable to the printer. The illustration below represents the 25-pin
connectors for the RS-232C cable (1038693).
The following illustration shows the pin assignments for the 9-pin to 25-pin IBM EIA
RS-232C serial cables.
These instructions are for connecting the printer to an IBM-compatible
personal computer using a dual asynchronous adapter or an external print
server.
13 25
1 14
9 to 25 Pin Cable Adapter,
such as IBM 6450242 (10 in.)
Shield
9 (F) 25 (M)
8-20
Lexmark 1038693 (50 ft)
Shield
25 (F)
Interfaces
25 (M)