There is a result of PostScript detection:
<ESC>%-12345X@PJL INFO VARIABLES
Then check section PERSONALITY.
This is a reply from 6P:
PERSONALITY=AUTO [2 ENUMERATED] AUTO PCL
This is a reply from PostScript capable printer:
PERSONALITY=AUTO [3 ENUMERATED] AUTO PCL POSTSCRIPT
There is a result of PostScript detection:
<ESC>%-12345X@PJL INFO VARIABLES
Then check section PERSONALITY.
This is a reply from 6P:
PERSONALITY=AUTO [2 ENUMERATED]
AUTO
PCL
This is a reply from PostScript capable printer:
PERSONALITY=AUTO [3 ENUMERATED]
AUTO
PCL
POSTSCRIPT