ecu access

Hi porsche experts,

i own a porsche cayenne s , 2004 model, us spec.

I would like to read the ecu using the obd2 socket and the kwp2000 programmer over k-line.
i don't succeed in this.
Can someone tell me how to do this exactly?
Do i have to keep the ecu from going to sleep?If yes, how?

Thanks in advance guys.