HP 24SII - Manual (Page 73)

When the buffer of the Model 24SII DES can receive more data, the
Model 24SII DES will send an XON to Computer A.
NOTE: For computers sending binary data and using XON/XOFF
handshaking, the input flow control (Recv) should be enabled and the
output flow control (Xmit) should be disabled. This will allow any XON
or XOFF character sent in the binary string to be passed through the
Model 24SII DES to the receiving device.
You may wish to write your own program for sending the port select
sequence to the Model 24SII DES instead of manually inserting it or
utilizing the hot keys provided in BayTech's supplied support software
program.
A simple procedure when using word processing programs is to
create an ASCII file for each printer which contains the Port Select
Code, the device module number (1 to 6), the device port number,
and the terminating character. This file could be named PRINTER1.
When you wish to select a particular device, you simply print this file
followed by the actual print file.
Another method is to make the port select sequence the first
characters of the text. These characters will be trapped by the Model
24SII DES and will not be sent to the printer. This method will work
only if the text of the print file is sent in an ASCII format.
You may also use a DOS batch file to send a port select sequence.
The DOS command typically used is the ECHO command. An
example of the ECHO command used to select a printer connected to
Port 2 of Module 2 using the default Port Select Code is as follows:
ECHO $PRINTER22>LPT1:.