Lexmark X644e User Guide

Page of 416
Interfaces
8-18
 
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:
The printer returns XON/XOFF with 2 stop bits in all cases.
The printer does not support DTR inversion.
Using the RS-232C Serial Interface
This section describes how to use the RS-232C serial interface. 
Connector 
Pin
39 ohm ±10%
GND
74LVC161284
1500 pF±20%