HP 170X - JetDirect Print Server, Руководство по установке и настройке

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32 CHAPTER 5: FTP PRINTING
Print Files
The HP JetDirect FTP server transfers print files to the
printer but does not interpret them. For proper
printing, print files must be in a language recognized
by the printer (such as PostScript, PCL, or unformatted
text). For formatted print jobs, you must first print to
a file from your application using the driver for the
selected printer, then transfer the print file to the
printer through an FTP session. For formatted print
files, use binary (image) type transfers.
Using FTP Printing
FTP Connections
Similar to standard FTP file transfers, FTP printing uses
two TCP connections: a control connection and a data
connection.
Control Connection
Using standard FTP, a control connection is opened by
the client to the FTP server on the HP JetDirect print
server. FTP control connections are used to exchange
commands between the client and the FTP server. The
HP JetDirect print server supports up to three control
connections (or FTP sessions) simultaneously. If the
number of allowed connections is exceeded, a
message indicating that service is not available will be
displayed.
FTP control connections use TCP port 21. Once an FTP
session is opened, it remains active until either the
client closes the connection or the connection is idle
for 900 seconds (15 minutes).