Status Readback Commands - HP Color LaserJet 5500 Technical Reference Manual

Status Readback Commands

Introduction
PJL allows applications to request configuration and status
information from the printer. The printer also can be
programmed to send unsolicited status information to the
application when printer events occur. For example, the
printer can send status information indicating the printer
door is open, toner is low, online/offline status, the text
displayed on the control panel, and other pertinent
information.
PJL status readback is especially useful during application
development. Status readback enables you to determine
that your application successfully changed feature settings
to your specifications.
This chapter describes the requirements for using status
readback, and explains the following status readback
commands:
INQUIRE requests the current value (PJL Current
Environment) for a specified environment variable.
DINQUIRE requests the default value (User Default
Environment) for a specified environment variable.
ECHO returns a comment to the host computer to
synchronize status information.
INFO requests a specified category of printer
information.
USTATUS allows the printer to send unsolicited status
messages, including device, job, page, and timed status.
USTATUSOFF turns off all unsolicited status.
This chapter also explains job recovery.
Status Readback Commands 7-1
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