Using The Rs-232C Serial Interface - Lexmark X644E Technical Reference Manual

SLCTIN* Receiver for the Lexmark X644e and X646ex
The following diagram illustrates the SLCTIN* receiver for the Lexmark X644e and
X646ex.
Serial Interface
The serial interface allows data to flow back and forth between the computer and the
printer. However, the serial interface transfers data at a slower rate than the parallel
interface.
If a serial connector is required, you may be able to install an RS-232C Serial Interface
Card, an External Serial Adapter, or an RS-232C Serial/Parallel 1284-C Interface
Card. See your printer documentation for more information.
Use RS-232C serial interface if the printer is more than 3.04 m (10 ft) from the
computer but less than 15.24 m (50 ft) away. (You can also use a 6.1 m (20 ft) Lexmark
cable to connect a printer and a computer located up to 20 feet apart.)
When using the serial interface, your printer has the following differences from the
serial interface on some other printers:
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Using the RS-232C Serial Interface

This section describes how to use the RS-232C serial interface.
Connector
Pin
39 ohm ± 10%
The printer returns XON/XOFF with 2 stop bits in all cases.
The printer does not support DTR inversion.
8-18
74LVC161284
1500 pF ± 20%
GND
Interfaces