Gaurang,
Please download and install SAP Plant Connectivity 2.3 (PCo) from Service Marketplace. You can obtain a license for PCo for free based on current ownership of SAP MII.
SCADVantage supports both OPC DA for current value Tag retrieval and OPC HDA for historical tag data retrieval. PCo has agents for both of these interfaces.
If you install PCo on the MII server, you will also have to set up Microsoft DCOM configuration on both the MII and SCADAVantage servers so tht the OPC Client (PCo) can communicate with the OPC Server (SCADAVantage) over a network. If you can install PCo on the SCADAVantage server then DCOM configuration is not required, and MII can communicate with PCo over the network without issue. Also, please review the installation and configuration guides for PCo prior to installing, these are available from the SAP help site.
Regards, Steve