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

EN Status Readback Commands 7-17
Comments:
When the printer receives the INFO command, it returns the
requested information. Only one category can be used for each INFO
command. Each category is described below, with the format of the
printer's response. If the printer does not support the specified
category, the returned information is as follows:
@PJL INFO category <CR><LF>
"?" <CR><LF>
<FF>
ID Category
The INFO ID command provides a way to identify the type of printer
used. For the HP LaserJet 4 printer, the INFO ID command prompts
the printer to return the following response:
@PJL INFO ID<CR><LF>
"LASERJET 4"<CR><LF>
<FF>
Note To maintain compatibility with future printers, applications should not
use the INFO ID command to identify printer features. Instead, the
more detailed INFO CONFIG command should be used (see the
following discussion on “The CONFIG Category”).
Some printers, such as the HP LaserJet 4ML printer, return “HP” in
front of the model name, for example:
@PJL INFO ID<CR><LF>
"HP LASERJET 4ML"<CR><LF>
<FF>
CONFIG Category
The INFO CONFIG command returns a series of lines listing
configuration information. Use this command to request information
such as which printer languages are installed, how many input and
output trays are installed, and how many font cartridge slots are in the
printer.