Scematic diagram for Multimaster PPi cable Please

I am a student in the faculty of engineering and in our project
we use siemens PLc s7-200 cpu222 and wincc flexible 2005.
we want a schematic diagram for the RS232/PPI multi-master cable to connect the PLC to HMI device ( SCADA) which is on our computer
Any Help Please??

Buy the cable. It's easier and takes less time. And I've never seen published a schematic for it either.

And they offer a USB to PPI version too!