HP PCL/PJL reference - Printer Job Language Technical Reference Manual

7-38 Status Readback Commands EN
The printer sends the unsolicited status associated with the JOB
command when the JOB command is parsed. The printer sends the
unsolicited status associated with the EOJ command when all of the
pages received before the EOJ command have been printed. To
maximize performance, HP printers start processing the next job
before the last page of the current job has been printed. Therefore,
the printer may return unsolicited JOB and EOJ status messages in
an order different than sent by the application or spooler. For
example, when printing two consecutive jobs, the unsolicited EOJ
status message associated with the first job may not arrive at the host
until after the JOB status message of the second job.
PAGE Variable
The USTATUS PAGE = ON command is used to notify the application
that a particular page finished printing. This is useful for applications
such as spoolers, where it is beneficial to monitor the job on a
page-by-page basis. For job recovery, described later in this chapter,
it is helpful to know which pages are completely printed.
The number of pages is incremented by one for each simplex page
formatted, and by two for each duplex page formatted. The page
count includes all pages printed and all pages processed in
non-printing mode since the last JOB or EOJ command. (This is
different than the PAGES = page count returned with the unsolicited
JOB status, which does not include pages processed in non-printing
mode.)
Example: Using Unsolicited Page Status
The following example enables unsolicited page status. The sample
HP LaserJet 4 printer response indicates the status messages that
the printer sends when processing a four-page job.
<ESC>%-12345X@PJL <CR><LF>
@PJL USTATUS PAGE = ON <CR><LF>
@PJL JOB <CR><LF>
@PJL ENTER LANGUAGE = PCL <CR><LF>
<ESC>E . . . Four-page PCL Job . . . <ESC>E
~<ESC>%-12345X@PJL <CR><LF>
@PJL EOJ <CR><LF>
<ESC>%-12345X