HP 220240 - Manual (Page 116)

For Digital systems, the dtr feature should always be set to the fixed high
value. When the DTR signal is fixed high (Fix-H) it indicates to the system
that the printer is ‘‘present.’’
4.5.6.5 Buffer Control (xon/xoff)
The buffer control (xon/xoff) feature uses software to regulate the flow of
data to the input buffer of the printer. It is sometimes referred to as
software handshaking protocol, a method the printer and the host computer
use to exchange on/off signals. These signals prevent the input buffer from
overflowing with data. If the input buffer becomes full and handshaking is
not enabled, the overflowing data will be lost. Xon/xoff must be enabled in
systems that use this software handshaking protocol to prevent the loss of
data.
4.5.6.6 End of Text/Acknowledge (etx/ack)
The end of text/acknowledge (etx/ack) feature is another type of
handshaking protocol on some systems to prevent data overflow. The
etx/ack feature also uses software to regulate the flow of data to the input
buffer by exchanging signals with the host computer. It is recommended
that this feature be enabled by systems that support etx/ack to prevent the
loss of data.
NOTE: The etx/ack feature is not supported on Digital systems. Use xon/
xoff if you have a Digital system.
4.5.7 DUPLEX Menu
The DUPLEX menu determines whether paper is printed on one or two
sides. The duplex printing mode can be selected under software control from
the host, or by using
Duplex
on the control panel. Duplex mode is indicated
when the Duplex indicator is on. See Table 3–3 for more information about
using
Duplex
.
NOTE:
Duplex mode cannot be selected if the printer is in manual feed
mode, has the envelope cassette or feeder installed, or is set to the
envelope/faceup position.
Table 4–18 shows the features and values of the DUPLEX menu.
Printer Configuration 4–31