Printer raw socket choose cassette

I wrote a php script which sends pdf files over raw socket to a printer.

$fp = pfsockopen("192.168.10.61",9100);     # Drucker IP
fwrite($fp, file_get_contents(__DIR__ . '/test.pdf'));      # Ausdruck 1
fclose($fp);

The printer does it’s job very well and without problems.

Now I’ve got a new printer with two cassettes, both are A4 but one with our letterhead and one without.

I want to print with cassette two, how is that possible?

I already changed the socket ports up to 9103 but that doesn’t help.

Printer-Model: kyocera P-4035i MFP KX