Communication between xA-systems
In theory yes.
Try using a generic OPC client first. DCOM settings might need adjustments. Asynchronous OPC DA is complex user wise. See attachment for details.
Just be careful with using Generic OPC Upload (name clashes can result in ugly fubar situations - avoid it).
The officially recommended method is Multisystem Integration.
we are connecting 2 800xA systems using Generic OPC (without uploader). If you have unique tags in your systems you should easily create your own control connections to read/write data by just using the names.
The only thing we had to do is to set DCOM for OPC Surrogate on the server side to start with 800xAService always.
So one off our 800xA system has 2 CS connect to 2 800xA OPC Serves on the other system to make the connection redundant.