Hi Rajeev,
If PCo is NOT installed on the FSGateway server, you will need to follow the Wonderware guidelines for OPC DCOM configuration for both FSGateway (server) and PCo (client) instances. I would also recommend that you obtain and install an OPC Client data viewer on the PCo server so that you can independently view OPC tag data from Wonderware at the PCo Server. this will also help resolve any DCOM issues should they arise.
Make sure you follow the Plant Connectivity Installation Guide specifically during installation of PCo.
Otherwise, you will need to maintain the correct port mappings between PCo AtneQuery Ports and MII so that you can establish any PCoQuery templates to browse tags and retrieve data from the Archesta system.
Regards, Steve