Hello Ted;

A DP/DP coupler is a special Profibus-DP slave, with 2 slave interfaces, that connect to 2 distinct DP-masters and allows them to exchange data between them.

You insert one DP/DP coupler instance on the Profibus network of each master, and configure the data exchanges as described in this document:

Configuration of I/O exchanges on a DP/DP COUPLER

https://support.industry.siemens.com/cs/ww/en/view/19281019

Hope this helps,

Daniel Chartier 

Hello Ted;

Sorry my first reply did not clarify the issue well enough.

You insert a DP/DP coupler in the hardware configuration of each master you want to interconnect. 

The best source of information on any Siemens equipment is always the manual:

https://support.industry.siemens.com/cs/ww/en/view/1179382

Study especially chapter 4, Configuring and commissioning.

Hope this helps,

Daniel Chartier