Before R12, customers on Oracle Process Manufacturing (OPM) usually used OPM MRP as the planning engine though there are customers who have successfully integrated OPM with Advanced Supply Chain Planning (ASCP). With R12, OPM MRP is now obsolete and is replaced by unconstrained ASCP in a centralized setup. Another significant change has been the inventory convergence for Discrete Manufacturing and Process Manufacturing. In 11i, OPM organizations are different from Discrete organizations and hence for integration with other modules, a 1:1 mapping needs to be done for OPM and Discrete Organizations. With R12, this is now not required.
There are many documents including user guides available which has details about how to integrate OPM with ASCP. But there are some practical challenges which come only with experience. We have lot of customers complaining about recipes not being collected (some or all).
First and foremost it is very important that you apply the latest patches for OPM on Source side and latest patches for ASCP on Destination side (in case of a decentralized architecture). Most of the problems arise due to customers not having the latest patches.
Second, it is important that you define the generic resources as plant resources for each organization. Many customers leave it at the generic level and hence the recipe does not get collected.
Third, while defining the formulas and recipes, it is important that you define the unit of measure conversions in case you have items with different primary units of measure.
Fourth, ensure that you have the correct setups in Product Development Security Manager for each organization.
There can be multiple other reasons for the integration not working but these are the most common sources of error.
So next time thinking about OPM with ASCP, keep these points in mind. By the way, your source can be 11i while the destination can be R12, provided both the databases are on the same major release.