Printer Status Requirements; Synchronizing Status Readback Responses - HP Color LaserJet 5500 Technical Reference Manual

Printer Status
Requirements
Synchronizing
Status Readback
Responses
7-2 Status Readback Commands
To receive status information from the printer, the
application must have program code that handles the
status information sent from the printer.
Status responses are directed to the printer's I/O port from
which the request is received. When using status readback,
applications must synchronize status messages to ensure
that status responses are indeed the requested status. To
clear any possible unread status responses requested by
previous applications, upon starting up, an application
should use the ECHO command as described in the ECHO
command section later in this chapter.
If unsolicited status is enabled, applications should
properly handle receiving unsolicited status responses at
any time. In particular, be aware that applications may
receive an unsolicited status response after requesting
printer status information.
The application and printer must be in a printer
environment that supports two-way communication
between the application and the printer. Printer sharing
devices, networks, and other printing system components
may not support this bi-directional communication. (Refer
to "Using Status Readback in a Multi-User System" in
Chapter 10.)