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

7-4 Status Readback Commands EN
Format of Status Readback Responses
When PJL sends printer status information to the host, the response
is in a readable ASCII format that always begins with the @PJL prefix
and ends with a <FF> character. For example, the readback response
for the INQUIRE command is:
@PJL INQUIRE [LPARM:personality | IPARM:port]
~variable<CR><LF>
value<CR><LF>
<FF>
Your application should be able to read all the data between the
“@PJL” header and the <FF> control code.
Lines within the PJL status response begin with a specific keyword,
as described in the command descriptions in this chapter, 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 format of the printer response for each STATUS READBACK
command is described in the command descriptions.