Requesting Printer Status; Using Status Readback In A Multi-User System - HP Color LaserJet 5500 Technical Reference Manual

Requesting Printer
Status
Using Status
Readback in a
Multi-User System
10-18 Programming Tips
When querying the printer for status, the response is not
immediate. Wait a fixed amount of time for a response and
then time out. If the printer is still working on a previous
print job, it may take a while before a response is received.
Your application should be able to discard unexpected
status, such as unsolicited status, and discard
unrecognizable lines. Lines within the PJL status response
begin with a specific keyword, as described in the command
description in Chapter 7, and end with the <CR><LF>
control codes. Future printers may support new keywords
in the PJL status response. Your application should ignore
those lines which it does not understand.
The printing system consists of all components involved in
the process of turning an application document into a
printed sheet of paper. Common printing system
components include the host computer, applications on the
host computer, the operating system used by the host
computer, the cable connecting the host computer to the
printer, and the printer. Other printing system components
can include printer sharing boxes, network servers, spoolers
running on network servers, and I/O cards installed in the
printer. For printer status readback to be useful, all
components must be bi-directional.
Some operating system environments, like Microsoft's
Windows, provide the components that interact with the
printer so Windows applications generally do not need to
support printer status readback.
The components that may generate printer queries include
the host application, the printer sharing box, the network
spooler, and the I/O card installed in the printer. Printer
status readback can allow many printing system
components to function more effectively, not just the host
application. For example, a network I/O card may inject a
PJL JOB command at the beginning of each job and a PJL