PostScript to PDF and Duplex/Tumble

Hello Everyone,

This is my first message to this list, i'm looking for some help.

I'm using Ghostscript for converting a Postscript generated file to PDF. It is working fine, except if in the postscript file there is this command :
<</Duplex true
/Tumble true
/EndOfSet false
>>setpagedevice

The Tumble is not recognized. I think it is maybe by design, because Duplex is not possible in PDF. But as my document is full duplex, and printed on a Canon Inkjet system, I want that in my PDF some pages are turned 180° for printing like Duplex Tumbled.

I have also tried to put /orientation 2, but it doesn't work either.

Can someone help me or give me some information how I could achieve this ? Maybe in the Postscript file directly, or in command line in gs ?

Thank you and regards
Philippe RITTER